@article {2687, title = {IR-UV Double-Resonance of Methyl Radicals and a Determination of the Detection Sensitivity of REMPI Bands}, journal = {Journal of Physical Chemistry A}, volume = {113}, number = {47}, year = {2009}, note = {ISI Document Delivery No.: 520FLTimes Cited: 3Cited Reference Count: 46Zhang, Weiqing Kawamata, Hiroshi Merer, Anthony J. Liu, Kopin}, month = {Nov}, pages = {13133-13138}, type = {Article}, abstract = {A novel method is exploited in this report to directly determine the relative detection sensitivity of the (2+1) resonance-enhanced multiphoton ionization (REMPI) bands of CH3 and CHD2 radicals. The basic idea is based on the simple fact that in an infrared (IR) absorption process the number of molecules being pumped from the lower state must be the same as the number of molecules in the excited upper state. Hence, the measured intensities of the respective REMPI bands should directly reflect their relative detection sensitivities. In order to ensure the processes involved and better quantify the measurements, extensive IR-UV double resonance spectroscopy was also performed. Using the REMPI-IR scheme, the IR spectrum of the vi fundamental (CH stretch) of CHD2 was obtained and assigned for the first time. Using the IR-REMPI approach, high-resolution (2+1) REMPI spectra via the Rydberg 3p states of both radicals were demonstrated in a rotationally specific manner for both the origin and vibronic-excited bands, from which the predissociation rates of the Rydberg 3p states were deduced.}, keywords = {CD3, CH3, INFRARED-SPECTROSCOPY, ISOMERIZATION, laser spectroscopy, MULTIPHOTON IONIZATION SPECTROSCOPY, PREDISSOCIATION DYNAMICS, RYDBERG STATE, SPECTRA, TRANSITION DIPOLE-MOMENT}, isbn = {1089-5639}, url = {://000271825800009}, author = {Zhang, W. Q. and Kawamata, H. and Merer, A. J. and Liu, K. P.} } @article {2499, title = {Surface-enhanced IR-visible sum frequency generation vibrational spectroscopy}, journal = {Physical Chemistry Chemical Physics}, volume = {11}, number = {18}, year = {2009}, note = {ISI Document Delivery No.: 436KPTimes Cited: 2Cited Reference Count: 79Li, Qifeng Kuo, Chiung Wen Yang, Zheng Chen, Peilin Chou, Keng C.}, pages = {3436-3442}, type = {Article}, abstract = {Surface-enhanced IR-visible sum frequency generation (SFG) was studied using Ag and Au films over nanospheres (AgFON and AuFON), which provided large area of reproducible nanoscale structures with well-defined morphology. SFG vibrational spectra for a self-assembled monolayer of octadecanethiol were investigated on spheres with diameters ranging from 300 nm to 620 nm. With an input wavelength of 532 nm, a sphere diameter near 360 nm produced the maximum enhancement, which was consistent with the localized surface-plasmon resonant wavelength identified by minimum reflectivity. The measured second-order susceptibility for the asymmetric CH3 stretch mode of octadecanethiol was enhanced by up to 27 times on AgFON, which corresponded to an SFG enhancement factor of similar to 730. The SFG enhancement factor for AuFON was a quarter of that from AgFON. The SFG enhancement factor for the symmetric CH3 mode was about 10 times smaller than that for the asymmetric CH3 mode. This difference can be explained by the highly directional electrical-field parallel to the surface, created at the junction between nanospheres. Polarization-dependent studies also indicated that excitations with the electrical field parallel to the surface was the main contribution to the observed surface enhancements, and the electrical field perpendicular to the surface offered little enhancement.}, keywords = {2ND-HARMONIC GENERATION, METAL NANOPARTICLES, NANOPARTICLES, NANOSPHERE, platinum, RAMAN-SCATTERING SERS, RHODAMINE 6G MOLECULES, SELF-ASSEMBLED MONOLAYERS, SILVER ELECTRODE, SPECTRA, SUPPORTED PD NANOPARTICLES, SURFACES, TOTAL-REFLECTION}, isbn = {1463-9076}, url = {://000265413300011}, author = {Li, Q. F. and Kuo, C. W. and Yang, Z. and Chen, P. L. and Chou, K. C.} } @article {2103, title = {Current approaches for global post-translational modification discovery and mass spectrometric analysis}, journal = {Analytica Chimica Acta}, volume = {627}, number = {1}, year = {2008}, note = {ISI Document Delivery No.: 358IYTimes Cited: 13Cited Reference Count: 77Hoffman, Michael D. Sniatynski, Matthew J. Kast, JuergenSp. Iss. SI}, month = {Oct}, pages = {50-61}, type = {Review}, abstract = {More and more attention is being focused on the analysis of post-translational modifications (PTMs) on proteins as researchers are continually learning how essential they are for proper cellular function. As there are hundreds of different types of known PTMs, traditional methods of modification analysis are incapable of comprehensively monitoring for post-translational modifications, a task which is a necessity for truly understanding a cell{\textquoteright}s biology. This review highlights recent developments in novel multiplexed methods of PTM analysis including: fluorescent stain and immuno-based methods, hardware-based mass spectrometric methods and computational-based mass spectrometric methods. Many of these techniques show great promise and will likely be a valuable resource for the biological community. (C) 2008 Elsevier B.V. All rights reserved.}, keywords = {computational, glycosylation, IDENTIFICATION, IONIZATION, marker ion, MASS SPECTROMETRY, MODIFIED PEPTIDES, neutral loss, post-translational modifications, protein array, PROTEIN-PHOSPHORYLATION, PROTEOMIC ANALYSIS, S-NITROSYLATION, SEQUENCES, SIGNALING NETWORKS, SPECTRA}, isbn = {0003-2670}, url = {://000259911600005}, author = {Hoffman, M. D. and Sniatynski, M. J. and Kast, J.} } @article {1399, title = {Determination of the location of naphthalene in the zeolite ZSM-5 host framework by solid-state H-1/Si-29 CP MAS NMR spectroscopy}, journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie}, volume = {84}, number = {2}, year = {2006}, note = {ISI Document Delivery No.: 040YKTimes Cited: 3Cited Reference Count: 23}, month = {Feb}, pages = {345-355}, type = {Article}, abstract = {The location of naphthalene in the zeolite ZSM-5 has been determined from solid-state H-1/Si-29 cross-polarization (CP) magic-angle-spinning (MAS) NMR data alone. With the peaks in the Si-29 spectrum assigned to the inequivalent Si sites in the zeolite from a two-dimensional INADEQUATE spectrum, the rates of cross polarization between the H-1 nuclei of the guest sorbate molecules and the Si-29 nuclei of the zeolite framework were used to determine the location of the naphthalene molecules by exploiting the proportional relationship between cross-polarization rate constants and H-1/Si-29 dipolar coupling second moments. The NMR structure determination was carried out on three different selectively deuterium-labeled naphthalene molecules (naphthalene-d(0), alpha-naphthalene-d(4), and beta-naphthalene-d(4)). The average of the molecule locations in agreement with all three sets of NMR data was found to be in excellent agreement with an existing single crystal XRD structure of the naphthalene-ZSM-5 complex.}, keywords = {COMPLEXES, cross polarization, CROSS-POLARIZATION, host-guest complexes, RAY-POWDER DIFFRACTION, SOLID-STATE NMR, SORBATE, SPECTRA, structure determination, zeolites}, isbn = {0008-4042}, url = {://000237417600033}, author = {Fyfe, C. A. and Brouwer, D. H.} } @article {1425, title = {Investigation of a 2D two-point maximum entropy regularization method for signal-to-noise ratio enhancement: application to CT polymer gel dosimetry}, journal = {Physics in Medicine and Biology}, volume = {51}, number = {10}, year = {2006}, note = {ISI Document Delivery No.: 054NQTimes Cited: 13Cited Reference Count: 32}, month = {May}, pages = {2599-2617}, type = {Article}, abstract = {This study presents a new method of image signal-to-noise ratio (SNR) enhancement by utilizing a newly developed 2D two-point maximum entropy regularization method (TPMEM). When utilized as an image filter, it is shown that 2D TPMEM offers unsurpassed flexibility in its ability to balance the complementary requirements of image smoothness and fidelity. The technique is evaluated for use in the enhancement of x-ray computed tomography (CT) images of irradiated polymer gels used in radiation dosimetry. We utilize a range of statistical parameters (e.g. root-mean square error, correlation coefficient, error histograms, Fourier data) to characterize the performance of TPMEM applied to a series of synthetic images of varying initial SNR. These images are designed to mimic a range of dose intensity patterns that would occur in x-ray CT polymer gel radiation dosimetry. Analysis is extended to a CT image of a polymer gel dosimeter irradiated with a stereotactic radiation therapy dose distribution. Results indicate that TPMEM performs strikingly well on radiation dosimetry data, significantly enhancing the SNR of noise-corrupted images (SNR enhancement factors > 15 are possible) while minimally distorting the original image detail (as shown by the error histograms and Fourier data). It is also noted that application of this new TPMEM filter is not restricted exclusively to x-ray CT polymer gel dosimetry image data but can in future be extended to a wide range of radiation dosimetry data.}, keywords = {ASTRONOMY, DECONVOLUTION, DOSE DISTRIBUTIONS, FT-RAMAN, IMAGE-RESTORATION, RADIATION, RESOLUTION, SPECTRA, TOMOGRAPHY, X-RAY}, isbn = {0031-9155}, url = {://000238384700016}, author = {Jirasek, A. and Matthews, Q. and Hilts, M. and Schulze, G. and Blades, M. W. and Burner, R. F. B.} } @article {1558, title = {Measurements of the vapor pressure of cubic ice and their implications for atmospheric ice clouds}, journal = {Geophysical Research Letters}, volume = {33}, number = {17}, year = {2006}, note = {ISI Document Delivery No.: 081QHTimes Cited: 17Cited Reference Count: 38Shilling, J. E. Tolbert, M. A. Toon, O. B. Jensen, E. J. Murray, B. J. Bertram, A. K.}, month = {Sep}, pages = {5}, type = {Article}, abstract = {Under conditions commonly found in Earth{\textquoteright}s atmosphere, water can form two solid phases; hexagonal ice (I-h) and cubic ice (I-c). Recent reports have suggested that Ic may form in the atmosphere under a wider range of conditions than previously believed. In light of these reports, the formation of Ic has been suggested as one contributing factor for in-situ observations of persistent in-cloud supersaturations in cold cirrus. However, an accurate evaluation of the contribution of Ic formation to the observed supersaturations requires knowledge of the saturation vapor pressure of Ic, which has not been measured. In this manuscript, we report direct measurements of the vapor pressure of Ic over the temperature range 180 - 190 K. Over this temperature range, the vapor pressure of the cubic phase is 10.5 +/- 2.5\% higher than that of the hexagonal phase. Field measurements of in-cloud supersaturations made during CRYSTAL-FACE are also re-analyzed and discussed.}, keywords = {AMORPHOUS WATER ICE, ASTROPHYSICAL IMPLICATIONS, CIRRUS CLOUDS, ELECTRON DIFFRACTION, FORMS, GLASSY, HEXAGONAL ICE, LOW-TEMPERATURE, SPECTRA, WATER, X-RAY-DIFFRACTION}, isbn = {0094-8276}, url = {://000240331600005}, author = {Shilling, J. E. and Tolbert, M. A. and Toon, O. B. and Jensen, E. J. and Murray, B. J. and Bertram, A. K.} } @article {1628, title = {On-line content uniformity determination of tablets using low-resolution Raman spectroscopy}, journal = {Applied Spectroscopy}, volume = {60}, number = {6}, year = {2006}, note = {ISI Document Delivery No.: 055FDTimes Cited: 5Cited Reference Count: 31}, month = {Jun}, pages = {672-681}, type = {Article}, abstract = {Analytical techniques for rapid and nondestructive content uniformity determination of pharmaceutical solid dosage forms have been studied for several years in an effort to replace the traditional wet chemistry procedures, which are labor intensive and time consuming. Both Raman spectroscopy and near-infrared spectroscopy have been used for this purpose, and predictability errors are approaching those of the traditional techniques. In this study, a low-resolution Raman spectrometer was utilized to demonstrate the feasibility of both rapid at-line and on-line determination of tablet content uniformity. Additionally, sampling statistics were reviewed in an effort to determine how many tablets should be assayed for specific. batch sizes. A good correlation was observed between assay values determined by high-performance liquid chromatography and Raman analysis. Due. to rapid acquisition times for the Raman data, it was possible to analyze far more samples than with wet chemistry methods, leading to a better statistical description of variation within the batch. For at-line experiments, the sampling volume was increased by rotating the laser beam during the acquisition period. For the on-line experiments, the sampling volume was increased by sampling from a stream of tablets moving underneath the Raman probe on a conveyor system. Finally, an approach is proposed for monitoring content uniformity immediately following the compaction process. In conclusion, Raman spectroscopy has potential as a rapid, nondestructive technique for at- or on-line determination of tablet content uniformity.}, keywords = {ACTIVE-SUBSTANCE, central limit theorem, COATED TABLETS, content uniformity, FORMS, INTACT TABLETS, NEAR-INFRARED SPECTROSCOPY, PARACETAMOL, process analytical technology, Raman spectroscopy, sampling, SPECTRA, STATE, TRANSMITTANCE SPECTROSCOPY}, isbn = {0003-7028}, url = {://000238434500013}, author = {Wikstrom, H. and Romero-Torres, S. and Wongweragiat, S. and Williams, J. A. S. and Grant, E. R. and Taylor, L. S.} } @article {1386, title = {Prediction of spectroscopic constants for diatomic molecules in the ground and excited states using time-dependent density functional theory}, journal = {Journal of Computational Chemistry}, volume = {27}, number = {2}, year = {2006}, note = {ISI Document Delivery No.: 999IGTimes Cited: 3Cited Reference Count: 52}, month = {Jan}, pages = {163-173}, type = {Article}, abstract = {Spectroscopic constants of the ground and next seven low-lying excited states of diatomic molecules CO, N-2, P-2, and ScF were computed using the density functional theory SAOP/ATZP model, in conjunction with time-dependent density functional theory (TD-DFT) and a recently developed Slater type basis set, ATZP. Spectroscopic constants, including the equilibrium distances r(e), harmonic vibrational frequency omega(e), vibrational anharmonicity omega(e)x(e), rotational constant B-e, centrifugal distortion constant D-e, the vibration-rotation interaction constant alpha(e), and the vibrational zero-point energy E-n(0), were generated in an effort to establish a reliable database for electron spectroscopy. By comparison with experimental values and a similar model with an established larger Slater-type basis set, et-QZ3P-xD, it was found that this model provides reliably accurate results at reduced computational costs, for both the ground and excited states of the molecules. The over all errors of all eight lowest lying electronic states of the molecules under study using the effective basis set are r(e)(+/- 4\%), omega(e)(+/- 5\% mostly without exceeding +/- 20\%), omega(e)x(e)(+/- 5\% mostly without exceeding 20\%, much more accurate than a previous study on this constant of +/- 30\%), B-e(+/- 8\%), D-e(+/- 10\%), alpha(e)(+/- 10\%), and E-n(0)(+/- 10\%). The accuracy obtained using the ATZP basis set is very competitive to the larger et-QZ3P-xD basis set in particular in the ground electronic states. The overall errors in r(e), omega(e)x(e) and alpha(e) in the ground states were given by +/- 0.7, +/- 10.1, and +/- 8.4\%, respectively, using the efficient ATZP basis set, which is competitive to the errors of +/- 0.5, +/- 9.2, and +/- 9.1\%, respectively for those constants using the larger et-QZ3P-xD basis set. The latter basis set, however, needs approximately four times of the CPU time on the National Supercomputing Facilities (Australia). Due to the efficiency of the model (TD-DFT, SAOP and ATZP), it will be readily applied to study larger molecular systems. (c) 2005 Wiley Periodicals, Inc.}, keywords = {Density Function Theroy, diatomic molecules, DIPOLE-MOMENT, ELECTRONIC-STRUCTURE, emission, EXCITATION-ENERGIES, excited, FREQUENCIES, GAUSSIAN-BASIS SETS, ground state, INDUCED POLARIZATION FUNCTIONS, ORBITALS, POTENTIALS, SPECTRA, spectroscopic constants, STATES, SURFACES}, isbn = {0192-8651}, url = {://000234382400005}, author = {Falzon, C. T. and Chong, D. P. and Wang, F.} } @article {1530, title = {Raman spectroscopy for tablet coating thickness quantification and coating characterization in the presence of strong fluorescent interference}, journal = {Journal of Pharmaceutical and Biomedical Analysis}, volume = {41}, number = {3}, year = {2006}, note = {ISI Document Delivery No.: 051CCTimes Cited: 22Cited Reference Count: 27}, month = {Jun}, pages = {811-819}, type = {Article}, abstract = {We report a novel approach to the measurement of colored tablet coating thickness, which employs Raman spectroscopy with univariate and multivariate data analysis. Our results suggest that Raman sensing can serve as a viable non-invasive means to quantify tablet coating thickness in the presence of a fluorescent ingredient in the coating formulation (food colorant Alphazurine FG or D\&C Blue No. 4). This study comparatively tests the advantage of several data transformation approaches, including mean centering, standard normal variate, and Savitzky-Golay smoothed second derivative as means of improving predictive models in the presence of fluorescence. By application of the partial least squares (PLS) calibration algorithm to establish optimum covariance between transformed spectral data and measured tablet coating thicknesses, we have been able to create predictive models with calibration errors as small as 4 mu m for a training set that spans colored coating thicknesses from 50 to 151 mu m. (c) 2006 Elsevier B.V. All rights reserved.}, keywords = {film coating, FLUORESCENCE, FORMS, INDUCED BREAKDOWN SPECTROSCOPY, near infrared spectroscopy, QUANTITATIVE-ANALYSIS, Raman spectroscopy, REFLECTANCE, SPECTRA, SPECTROMETRY}, isbn = {0731-7085}, url = {://000238137100019}, author = {Romero-Torres, S. and Perez-Ramos, J. D. and Morris, K. R. and Grant, E. R.} } @article {1344, title = {Solid state NMR investigation of the structure of AlPO4-14A}, journal = {Microporous and Mesoporous Materials}, volume = {88}, number = {1-3}, year = {2006}, note = {ISI Document Delivery No.: 004TCTimes Cited: 5Cited Reference Count: 14}, month = {Jan}, pages = {163-169}, type = {Article}, abstract = {The as-synthesized aluminophosphate framework material AlPO4-14A has a number of unique structural features related to the connectivities in the network of Al and P atoms. One tetrahedral Al atom is present that is linked, via Al-O(H)-Al bonds to two octahedral Al atoms and, consequently to only two P atoms. However, ail Al/P ratio of one is maintained as each of these octahedral Al atoms is connected to five P atoms in addition to the Al-O(H)-Al linkage. This connectivity network means that a framework made up of alternating Al and P atoms cannot be obtained by calcination. A variety of H-1, Al-27, and P-31 solid state NMR experiments have been employed to characterize the AlPO4-14A structure. A fast H-1 MAS experiment showed that the template was in the protonated form and a H-1 {Al-27} TRAPDOR experiment identified the resonance of the {\textquoteright}framework{\textquoteright} proton. The Al-27 and P-31 resonances were completely assigned by the Al-27 -> P-31 INEPT heteronuclear correlation experiment and the quadrupolar parameters of the Al-27 signals determined from the Al-27 MQMAS experiment. Lastly, the complete assignment of both Al-27 and P-31 resonances made it possible to qualitatively determine the location and orientation of the template molecule within the framework from two-dimensional dipolar-based H-1 -> P-31 cross-polarization and H-1 -> Al-27 TEDOR heteronuclear correlation experiments. The data from these experiments confirm in detail the AlPO4-14A structure and will be useful benchmarks for the investigation of other structures for which diffraction data are limited. (c) 2005 Elsevier Inc. All rights reserved.}, keywords = {aluminophosphate, DIFFRACTION, HETCOR, solid state NMR, SPECTRA, SPINS, STRUCTURE, zeolite}, isbn = {1387-1811}, url = {://000234774100021}, author = {Brouwer, D. H. and Chezeau, J. M. and Fyfe, C. A.} } @article {1584, title = {Testing assumptions about solute concentration dependence in liquid crystal NMR}, journal = {Journal of Physical Chemistry B}, volume = {110}, number = {3}, year = {2006}, note = {ISI Document Delivery No.: 008NATimes Cited: 2Cited Reference Count: 24}, month = {Jan}, pages = {1363-1368}, type = {Article}, abstract = {The NMR spectra of four solutes, used as probes of liquid crystal orientational order, were analyzed. For each solute, samples were prepared at different solute concentrations, and the concentration dependence was used to extrapolate zero-concentration properties. The mean-field (Maier-Saupe) model when applied to solutes neglects solute-solute interactions and assumes all solutes in a mixed-solute sample see the same average environment. The first assumption is only valid as one approaches zero concentration, while experiments are typically carried out at concentrations between 0 and 10 mol \%. The solute concentration dependence has in the past been "scaled out" using an internal solute reference as an orientational standard. We measured the concentration dependence of the orientational order parameter and calculate the corresponding interaction energies based on a mean-field interaction potential for a solute. We find agreement at the 3\% level between experiments for different solutes while using (i) the zero-concentration values as solute-dependent orientational references and (ii) scaling to either order parameters or interaction energies; these two scalings gave equivalent but not identical results. We find, too, that errors inherent in the experiment and the calculations will limit attempts to refine the theory to push the comparisons beyond the 2\% level.}, keywords = {ANISOTROPIES, ELASTOMERS, ELECTRON-DIFFRACTION, MOLECULAR-STRUCTURE, ORDER, ORIENTATION, PHASE, SPECTRA}, isbn = {1520-6106}, url = {://000235046300041}, author = {Taggar, A. S. and Campbell, C. J. and Yethiraj, A. and Burnell, E. E.} } @article {1191, title = {Ansatz for the evaluation of the relativistic contributions to core ionization energies in complex molecules involving heavy atoms}, journal = {International Journal of Quantum Chemistry}, volume = {104}, number = {4}, year = {2005}, note = {ISI Document Delivery No.: 948JFTimes Cited: 4Cited Reference Count: 468th European Workshop on Quantum Systems in Chemistry and Physics (QSCP 8)AUG 30-SEP 04, 2003Spetses Isl, GREECE}, month = {Sep}, pages = {397-410}, type = {Proceedings Paper}, abstract = {On the basis of numerical, ab initio Delta DF and Delta HF computations of 1s-core, 2s-core, and 2p-core ionization energies of atoms, from Li through Xe, an allometric empirical formula that was proposed for evaluating relativistic corrections (including QED effects) to nonrelativistic values is assessed for homogeneous sets of elements in the periodic table. The two coefficients involved in this formula are precisely determined for 1s-core ionization in the sets of atoms Be-Ne, Mg-Ar, Zn-Kr, and Cd-Xe; 2s-core ionization in the sets of atoms Mg-Ar, Zn-Kr, and Cd-Xe; and 2p-core ionization in the set Mg-Ar. It is shown that the medium relative error on the results obtained using this formula, with respect to those directly computed, decreases from a few percent to a few hundredths of 1\% when the depth of the ionized level increases. This formula could be used to include relativistic (and QED) corrections to results yielded by simpler, nonrelativistic calculations on complex molecules involving heavy atoms. (c) 2005 Wiley Periodicals, Inc.}, keywords = {1S, 2p core ionizations, 2S, allometric fits, and QED, contributions, DENSITY-FUNCTIONAL CALCULATION, ELECTRON BINDING-ENERGIES, HOLE STATES, relativistic, relaxation, SPECTRA, spin-orbit}, isbn = {0020-7608}, url = {://000230711300003}, author = {Maruani, J. and Kuleff, A. I. and Chong, D. P. and Bonnelle, C.} } @article {1119, title = {Determining the geometry of strongly hydrogen-bonded silanols in a layered hydrous silicate by solid-state nuclear magnetic resonance}, journal = {Journal of Chemical Physics}, volume = {122}, number = {5}, year = {2005}, note = {ISI Document Delivery No.: 895RGTimes Cited: 7Cited Reference Count: 45}, month = {Feb}, pages = {10}, type = {Article}, abstract = {High-resolution solid-state NMR spectroscopy is exploited to obtain structural constraints involving strongly hydrogen-bonded silanols in octosilicate, a prominent member of the layered hydrous sodium silicates. Proton-silicon cross-polarization dynamics reveals that octosilicate contains two types of Q(3) silicons present in hydrogen-bonded -Si-O-H...O-Si- and -Si-O{\textendash}type sites which can only be distinguished by their different abilities to cross polarize and the different mobilities of neighboring hydrous species. The theoretical analysis of the oscillating components of the polarization transfer buildup curves suggests that the model of heteronuclear pairs is an adequate description of the quantum spin system within hydrogen-bonded -Si-O-H...O-Si- fragments. We also show that dipolar modulated, slow speed magic-angle Si-29 NMR spectrum provides unique geometric information on strongly hydrogen-bonded silanols. The dipolar modulated spinning sidebands contain all the information necessary to determine the internuclear Si...H distances as well as the magnitude and orientation of the principal elements of the Si-29 chemical shielding tensor in the molecular frame. The data provide definite proof of the intralayer character of strongly hydrogen-bonded silanol groups in a bridging, albeit not symmetric, position between neighboring tetrahedra. The approach developed in this work may be useful to obtain structural information on related layered alkali metal silicates, silica gels as well as on other classes of microporous materials. (C) 2005 American Institute of Physics.}, keywords = {DYNAMICS, MAGADIITE, MAS, NMR CROSS-POLARIZATION, RESOLUTION, ROTATING SOLIDS, SIDE-BAND, SPECTRA, SPECTROSCOPY, SPIN-EXCHANGE}, isbn = {0021-9606}, url = {://000226880100042}, author = {Gardiennet, C. and Marica, F. and Fyfe, C. A. and Tekely, P.} } @article {1076, title = {Ground and first-excited global potential energy surfaces of the H2O+-He complex: Predictions of ion mobilities}, journal = {International Journal of Quantum Chemistry}, volume = {101}, number = {1}, year = {2005}, note = {ISI Document Delivery No.: 872KKTimes Cited: 2Cited Reference Count: 29}, month = {Jan}, pages = {1-7}, type = {Article}, abstract = {Ion mobilities of H2O+ drifting in helium are calculated and compared with experiment. These calculations employ global potential energy surfaces of the H2O+-He complex, which in the present case were calculated ab initio at the unrestricted MP2 level of theory using a basis set of aug-cc-pVTZ quality, and treating the ion as a rigid body. Details are presented of the general characteristics of both the ground and first-excited electronic states of the complex. Although only the ground-state surface was used for the mobility calculations, the ab initio determination of the ground state necessitated the inclusion of the first-excited state owing to the presence of a crossing between the two. This crossing is also described. Mobilities calculated from the global surfaces are in good agreement with experiment. (C) 2004 Wiley Periodicals, Inc.}, keywords = {AB-INITIO, COLLISIONAL ALIGNMENT, first-excited state, global energy, H2O+-He complex, HELIUM, INDUCED ROTATIONAL ALIGNMENT, ion mobility, MICROSOLVATION, MOLECULAR-DYNAMICS, MP2, SPECTRA, SUPERSONIC EXPANSIONS, SURFACE, VELOCITY, WATER CATION}, isbn = {0020-7608}, url = {://000225205900001}, author = {Chen, X. and Thachuk, M.} } @article {1114, title = {Measurement of NMR cross-polarization (CP) rate constants in the slow CP regime: Relevance to structure determinations of zeolite-sorbate and other complexes by CP magic-angle spinning NMR}, journal = {Journal of Physical Chemistry A}, volume = {109}, number = {28}, year = {2005}, note = {ISI Document Delivery No.: 945UBTimes Cited: 8Cited Reference Count: 22}, month = {Jul}, pages = {6187-6192}, type = {Article}, abstract = {When analyzing I -> S variable contact time cross-polarization (CP) curves, the spin dynamics are usually assumed to be describable in the "fast CP regime" in which the growth of the S spin magnetization is governed by the rate of cross polarization while its decay is governed by the rate of I spin Tip relaxation. However, in the investigation of the structures of zeolite-sorbate and other complexes by polarization transfer this will not necessarily be the case. We discuss the measurement of I -> S CP rate constants under the "slow CP regime" in which the rate of Tip relaxation is fast compared to the rate of cross polarization, leading to a reversal of the usual assumptions such that the rate or growth is governed by the rate of I spin Tip relaxation while the decay is governed by the rate of cross polarization (and the S spin Tip relaxation). It is very important to recognize when a system is in the slow CP regime, as an analysis assuming the normal fast CP will lead to erroneous data. However, even when the slow CP regime is recognized, it is difficult to obtain absolute values for the CP rate constants from fits to standard CP curves, since the CP rate constant is correlated to the scaling factor, the contribution from Si-29 T-1 rho relaxation is ignored, and it is difficult to obtain reliable data at very long contact times. The use of a S-29{H-1} CP "drain" or "depolarization" experiment, which measures absolute values of the CP rate constants, is therefore proposed as being most appropriate for theses situations. To illustrate the importance of these observations, measurements of the H-1-Si-29 CP rate constants in the p-dichlorobenzene/ZSM-5 sorbate-zeolite complex by Si-29{H-1} CP and CP drain magic-angle spinning (MAS) NMR experiments are presented and compared and used to determine the location of the guest sorbate molecules in the cavities of the host zeolite framework.}, keywords = {DYNAMICS, SILICATE, SOLID-STATE NMR, SPECTRA, ZSM-5}, isbn = {1089-5639}, url = {://000230526600007}, author = {Fyfe, C. A. and Brouwer, D. H. and Tekely, P.} } @article {1069, title = {Molecules with large-amplitude torsional motion partially oriented in a nematic liquid crystal: Ethane and isotopomers}, journal = {Journal of Physical Chemistry A}, volume = {109}, number = {48}, year = {2005}, note = {ISI Document Delivery No.: 990RPTimes Cited: 10Cited Reference Count: 48}, month = {Dec}, pages = {11027-11036}, type = {Article}, abstract = {An NMR study on ethane and five isotopomers dissolved in the nematic liquid crystal Merck ZLI 1132 is performed. A consistent set of dipolar and quadrupolar couplings is obtained. The dipolar couplings are corrected for harmonic vibrational effects, while the contribution from the torsional motion is incorporated classically. The corrected dipolar couplings cannot be understood in terms of a reasonable molecular structure unless effects of the reorientation-vibration interaction are taken into account. Assuming that the reorientation-vibration contributions that are known for the methyl group in methyl fluoride are transferable to ethane, excellent agreement between observed and calculated dipolar couplings is obtained on the basis of the ethane gas-phase structure. The observed and calculated deuterium quadrupolar couplings show discrepancies supporting the notion that average electric field gradients are important in liquid-crystal solvents. An important consequence of the transferability of the reorientation-vibration correlation is that in other molecules with a methyl group the same procedure as for ethane can be followed. Inclusion of this effect generally removes the need to interpret changes in observed dipolar couplings in terms of elusive chemical effects.}, keywords = {ANISOTROPIC, ELECTRIC-FIELD GRADIENTS, ENVIRONMENTS, FORCE-FIELDS, H-2 NMR, NUCLEAR-MAGNETIC-RESONANCE, orientational order, POLYATOMIC-MOLECULES, ROTATION, SPECTRA, VIBRATIONS}, isbn = {1089-5639}, url = {://000233761200026}, author = {Burnell, E. E. and de Lange, C. A. and Barnhoorn, J. B. S. and Aben, I. and Levelt, P. F.} } @article {897, title = {Accuracy and precision of manual baseline determination}, journal = {Applied Spectroscopy}, volume = {58}, number = {12}, year = {2004}, note = {ISI Document Delivery No.: 879GJTimes Cited: 11Cited Reference Count: 17}, month = {Dec}, pages = {1488-1499}, type = {Article}, abstract = {Vibrational spectra often require baseline removal before further data analysis can be performed. Manual (i.e., user) baseline determination and removal is a common technique used to perform this operation. Currently, little data exists that details the accuracy and precision that can be expected with manual baseline removal techniques. This study addresses this current lack of data. One hundred spectra of varying signal-to-noise ratio (SNR), signal-to-baseline ratio (SBR), baseline slope, and spectral congestion were constructed and baselines were subtracted by 16 volunteers who were categorized as being either experienced or inexperienced in baseline determination. In total, 285 baseline determinations were performed. The general level of accuracy and precision that can be expected for manually determined baselines from spectra of varying SNR, SBR, baseline slope, and spectral congestion is established. Furthermore, the effects of user experience on the accuracy and precision of baseline determination is estimated. The interactions between the above factors in affecting the accuracy and precision of baseline determination is highlighted. Where possible, the functional relationships between accuracy, precision, and the given spectral characteristic are detailed. The results provide users of manual baseline determination useful guidelines in establishing limits of accuracy and precision when performing manual baseline determination, as well as highlighting conditions that confound the accuracy and precision of manual baseline determination.}, keywords = {baseline correction, baseline determination, CHROMATOGRAPHY, FLUORESCENCE, manual baseline removal, RAMAN-SPECTROSCOPY, SPECTRA, spectral baselines, SUBTRACTION}, isbn = {0003-7028}, url = {://000225704100017}, author = {Jirasek, A. and Schulze, G. and Yu, M. M. L. and Blades, M. W. and Turner, R. F. B.} } @article {897, title = {Accuracy and precision of manual baseline determination}, journal = {Applied Spectroscopy}, volume = {58}, number = {12}, year = {2004}, note = {ISI Document Delivery No.: 879GJTimes Cited: 11Cited Reference Count: 17}, month = {Dec}, pages = {1488-1499}, type = {Article}, abstract = {Vibrational spectra often require baseline removal before further data analysis can be performed. Manual (i.e., user) baseline determination and removal is a common technique used to perform this operation. Currently, little data exists that details the accuracy and precision that can be expected with manual baseline removal techniques. This study addresses this current lack of data. One hundred spectra of varying signal-to-noise ratio (SNR), signal-to-baseline ratio (SBR), baseline slope, and spectral congestion were constructed and baselines were subtracted by 16 volunteers who were categorized as being either experienced or inexperienced in baseline determination. In total, 285 baseline determinations were performed. The general level of accuracy and precision that can be expected for manually determined baselines from spectra of varying SNR, SBR, baseline slope, and spectral congestion is established. Furthermore, the effects of user experience on the accuracy and precision of baseline determination is estimated. The interactions between the above factors in affecting the accuracy and precision of baseline determination is highlighted. Where possible, the functional relationships between accuracy, precision, and the given spectral characteristic are detailed. The results provide users of manual baseline determination useful guidelines in establishing limits of accuracy and precision when performing manual baseline determination, as well as highlighting conditions that confound the accuracy and precision of manual baseline determination.}, keywords = {baseline correction, baseline determination, CHROMATOGRAPHY, FLUORESCENCE, manual baseline removal, RAMAN-SPECTROSCOPY, SPECTRA, spectral baselines, SUBTRACTION}, isbn = {0003-7028}, url = {://000225704100017}, author = {Jirasek, A. and Schulze, G. and Yu, M. M. L. and Blades, M. W. and Turner, R. F. B.} } @article {1002, title = {Is HAM/3 (Hydrogenic Atoms in Molecules, Version 3) a semiempirical version of DFT (density functional theory) for ionization processes?}, journal = {Journal of the Brazilian Chemical Society}, volume = {15}, number = {2}, year = {2004}, note = {ISI Document Delivery No.: 823IBTimes Cited: 7Cited Reference Count: 69}, month = {Mar-Apr}, pages = {282-291}, type = {Article}, abstract = {We calculated valence-electron vertical ionization potentials (VIPs) of nine small molecules, plus uracil and C2F4, by several different methods: semiempirical HAM/3 and AM1 methods, different nonempirical DFT models such as uDI(B88-P86)/cc-pVTZ and -epsilon(SAOP)/TZP, and ab initio Hartree-Fock (HF)/cc-pVTZ. HAM/3 reproduced numerical values more closely to those calculated by the nonempirical DFTs than to those obtained by HF method. Core-electron binding energies (CEBEs) of aniline, nitrobenzene and p-nitro aniline, were also calculated by HAM/3 and nonempirical DeltaFT using DE method. A nonempirical DFT model, designated as DeltaE(KS) (PW86-PW91)/TZP model, resulted accurate CEBEs ( average absolute deviation of 0.14 eV) with high efficiency. Although absolute magnitude of HAM/3 CEBEs has error as much as 3 eV, the error in the chemical shifts DeltaCEBE is much smaller at 0.55 eV. While the CEBE results do not lead to any definite answer to the question in the title, the trends in valence-electron VIPs indicate that HAM/3 does not approximate DFT with accurate exchange-correlation potentials, but seems to simulate approximate functionals such as B88-P86.}, keywords = {ACCURATE, BASIS-SET, CEBE, DFT, ELECTRON BINDING-ENERGIES, ESCA, EXCHANGE-ENERGY, HAM-3, HAM/3, MO THEORY, ORGANIC-MOLECULES, RAY PHOTOELECTRON-SPECTROSCOPY, SPECTRA, SUBSTITUTED BENZENES, vertical ionization potential, ZETA}, isbn = {0103-5053}, url = {://000221603000019}, author = {Takahata, Y. and Chong, D. P. and Segala, M.} } @article {1008, title = {Microwave spectra and structures of KrAuF, KrAgF, and KrAgBr; Kr-83 nuclear quadrupole coupling and the nature of noble gas-noble metal halide bonding}, journal = {Journal of the American Chemical Society}, volume = {126}, number = {4}, year = {2004}, note = {ISI Document Delivery No.: 768GATimes Cited: 42Cited Reference Count: 76}, month = {Feb}, pages = {1235-1246}, type = {Article}, abstract = {Microwave spectra of the complexes KrAuF and KrAgBr have been measured for the first time using a cavity pulsed jet Fourier transform microwave spectrometer. The samples were prepared by laser ablation of the metal from its solid and allowing the resulting plasma to react with an appropriate precursor (Kr, plus SF6 or Br-2) contained in the backing gas of the jet (usually At). Rotational constants; geometries; centrifugal distortion constants; vibration frequencies; and Au-197, Br-79, and Br-81 nuclear quadrupole coupling constants have all been evaluated. The complexes are unusually rigid and have short Kr-Au and Kr-Ag bonds. The Au-197 nuclear quadrupole coupling constant differs radically from its value in an AuF monomer. In addition Kr-83 hyperfine structure has been measured for KrAuF and the previously reported complex KrAgF. The geometry of the latter has been reevaluated. Large values for the Kr-83 nuclear quadrupole coupling constants have been found for both complexes. Both the Au-197 and Kr-83 hyperfine constants indicate a large reorganization of the electron distribution on complex formation. A thorough assessment of the nature of the noble gas-noble metal bonding in these and related complexes (NgMX; Ng is a noble gas, M is a noble metal, and X is a halogen) has been carried out. The bond lengths are compared with sums of standard atomic and ionic radii. Ab initio calculations have produced dissociation energies along with Mulliken populations and other data on the electron distributions in the complexes. The origins of the rigidity, dissociation energies, and nuclear quadrupole coupling constants are considered. It is concluded that there is strong evidence for weak noble gas-noble metal chemical bonding in the complexes.}, keywords = {CHEMICAL-BONDS, DIPOLE MOMENT, ELECTRIC-RESONANCE METHOD, GROUND-STATE, HYPERFINE CONSTANTS, MILLIMETER-WAVE, MOLECULAR-CONSTANTS, PURE ROTATIONAL, SPECTRA, SUBMILLIMETER-WAVE SPECTRA, VANDERWAALS COMPLEX}, isbn = {0002-7863}, url = {://000188534200055}, author = {Thomas, J. M. and Walker, N. R. and Cooke, S. A. and Gerry, M. C. L.} } @article {728, title = {Identification and interpretation of generalized two-dimensional correlation spectroscopy features through decomposition of the perturbation domain}, journal = {Applied Spectroscopy}, volume = {57}, number = {12}, year = {2003}, note = {ISI Document Delivery No.: 753MHTimes Cited: 8Cited Reference Count: 33}, month = {Dec}, pages = {1561-1574}, type = {Article}, abstract = {Generalized two-dimensional correlation spectroscopy offers great scope for revealing the behavior of relationships between components of a system under empirical study. We have developed methods that aid in the interpretation of two-dimensional correlation spectroscopy. These methods include reference patterns for two-dimensional correlation and correlation coefficient maps, their superposition and joint interpretation, and the use of delta functions to decompose them in the perturbation domain. We show how their joint use permits discrimination between similar two-dimensional correlation map features on the basis of different correlation coefficients. We also show how the decomposition of maps into the perturbation domain reflects the dynamic behavior of spectral features over the course of the perturbation and permits discrimination between otherwise highly similar two-dimensional correlation crosspeaks. These approaches simplify the interpretation of two-dimensional correlation spectroscopy maps and facilitate access to their rich information content.}, keywords = {coefficient maps, COMPONENT ANALYSIS, correlation, FT-IR SPECTROSCOPY, INFRARED CORRELATION SPECTROSCOPY, INTENSITY CHANGES, MONOLAYER FILMS, perturbation domain decomposition, RAMAN-SPECTRA, reference patterns, SAMPLE-SAMPLE, SECONDARY STRUCTURE, SIMULATIONS, SPECTRA, trajectory peaks, two-dimensional correlation spectra}, isbn = {0003-7028}, url = {://000187234800014}, author = {Schulze, G. and Jirasek, A. and Blades, M. W. and Turner, R. F. B.} } @article {728, title = {Identification and interpretation of generalized two-dimensional correlation spectroscopy features through decomposition of the perturbation domain}, journal = {Applied Spectroscopy}, volume = {57}, number = {12}, year = {2003}, note = {ISI Document Delivery No.: 753MHTimes Cited: 8Cited Reference Count: 33}, month = {Dec}, pages = {1561-1574}, type = {Article}, abstract = {Generalized two-dimensional correlation spectroscopy offers great scope for revealing the behavior of relationships between components of a system under empirical study. We have developed methods that aid in the interpretation of two-dimensional correlation spectroscopy. These methods include reference patterns for two-dimensional correlation and correlation coefficient maps, their superposition and joint interpretation, and the use of delta functions to decompose them in the perturbation domain. We show how their joint use permits discrimination between similar two-dimensional correlation map features on the basis of different correlation coefficients. We also show how the decomposition of maps into the perturbation domain reflects the dynamic behavior of spectral features over the course of the perturbation and permits discrimination between otherwise highly similar two-dimensional correlation crosspeaks. These approaches simplify the interpretation of two-dimensional correlation spectroscopy maps and facilitate access to their rich information content.}, keywords = {coefficient maps, COMPONENT ANALYSIS, correlation, FT-IR SPECTROSCOPY, INFRARED CORRELATION SPECTROSCOPY, INTENSITY CHANGES, MONOLAYER FILMS, perturbation domain decomposition, RAMAN-SPECTRA, reference patterns, SAMPLE-SAMPLE, SECONDARY STRUCTURE, SIMULATIONS, SPECTRA, trajectory peaks, two-dimensional correlation spectra}, isbn = {0003-7028}, url = {://000187234800014}, author = {Schulze, G. and Jirasek, A. and Blades, M. W. and Turner, R. F. B.} } @article {610, title = {Influence of F content on the composition of Al-rich synthetic phlogopite: Part II. Probing the structural arrangement of aluminum in tetrahedral and octahedral layers by Al-27 MQMAS and H-1/F-19-Al-27 HETCOR and REDOR experiments}, journal = {American Mineralogist}, volume = {88}, number = {7}, year = {2003}, note = {ISI Document Delivery No.: 699FDTimes Cited: 10Cited Reference Count: 28}, month = {Jul}, pages = {1046-1054}, type = {Article}, abstract = {The influence of F substitution on the local structure of Al in the tetrahedral and octahedral sheets of synthetic Al-rich phlogopite samples with nominal gel compositions of K(Mg3-xAlx)[Al1+xSi3-xO10] (OH)(y)(F)(2-y) between 0.0 less than or equal to x less than or equal to 0.8 and 0.5 less than or equal to y less than or equal to 1.8, was studied by Al-27 MAS, MQMAS, {H-1/F-19} {\textendash}> Al-27 2D CPMAS (HETCOR) and {H-1/F-19} Al-27 REDOR solid-state NMR and by IR spectroscopy. Changes in intensity of the absorption bands in the OH-stretching region of the IR spectra clearly indicate the incorporation of octahedral Al. Signals from the different phases can be separated in the Al-27 MQMAS NMR spectra by generation of an isotropic dimension in F1. The Al-27 quadrupolar parameters of the four phases were estimated from Al-27 MAS NMR spectra obtained at 104.26 and 208.42 MHz. The quadrupolar coupling constant and isotropic chemical shift increases with increasing Al content for the Al-IV site in phlogopite. The Al-VI site shows a clear increase of the asymmetry parameter and C-Q with increasing F content. The estimated Al-27 signal areas show the lowest amount of impurity phases at high OH contents and a stabilization of Al-VI sites by hydroxyl groups. The {H-1} {\textendash}> Al-27 2D CPMAS (HETCOR) NMR experiment at short contact times provides information about site neighborhoods of tetrahedral Al sites and Mg3OH as well as Mg2AlOH sites, whereas magnetization is only transferred to the octahedral At sites from hydroxyl groups in Mg2AlOH sites. The {F-19} {\textendash}> Al-27 2D CPMAS (HETCOR) NMR spectrum is dominated by Al-IV sites coupled to the Mg3F complex in phlogopite. Resonances from Mg2AlF complexes are not observed. Finally, the {H-1/F-19} Al-27 REDOR experiments support the results of the 2D CPMAS (HETCOR) experiments.}, keywords = {ANGLE-SPINNING NMR, DOUBLE-RESONANCE, F-19 MAS-NMR, FLUORINE, HIGH-FIELD, NMR, QUADRUPOLAR NUCLEI, SI-29, SOLID-STATE NMR, SPECTRA, SUBSTITUTION}, isbn = {0003-004X}, url = {://000184045300013}, author = {Fechtelkord, M. and Behrens, H. and Holtz, F. and Bretherton, J. L. and Fyfe, C. A. and Groat, L. A. and Raudsepp, M.} } @article {719, title = {Laser spectroscopy of VS: hyperfine and rotational structure of the C-4 Sigma(-)-X-4 Sigma(-) transition}, journal = {Journal of Molecular Spectroscopy}, volume = {220}, number = {1}, year = {2003}, note = {ISI Document Delivery No.: 699VMTimes Cited: 11Cited Reference Count: 20}, month = {Jul}, pages = {87-106}, type = {Article}, abstract = {The (0,0) and (0, 1) bands of the C(4)Sigma(-)-X(4)Sigma(-) electronic transition of VS (near 809 and 846 nm, respectively) have been recorded at high resolution by laser-induced fluorescence, following the reaction of laser-ablated vanadium atoms with CS2 under supersonic free-jet conditions. A least squares fit to the resolved hyperfine components of the rotational lines gives the rotational constants and bond lengths as C(4)Sigma(-): B-o = 0.188898 +/- 0.000027 cm(-1), r(o) = 2.1315 Angstrom; X(4)Sigma(-): B-0 = 0.203684 +/- 0.000025 cm(-1), r(o) = 2.0526 Angstrom. The electron spin parameters for the two states show that there are some similarities between the states of VS and those of VO, but the hyperfine parameters show that the compositions of the partly filled molecular orbitals are by no means the same. The ground state Fermi contact parameter of VS, b (X(4)Sigma(-)), is only 58\% of that of the ground state of VO, which implies that the sigma orbital of the ground sigmadelta(2) electron configuration has less than 50\% vanadium 4s character. Similarly, the excited state Fermi contact parameter, b(C(4)Sigma(-)), is very much smaller than that of VO. No local rotational perturbations have been found in the C(4)Sigma(-) state of VS, though an internal hyperfine perturbation between the F-2 and F-3 electron components at low N confuses the hyperfine structure and induces some forbidden (DeltaJ = +/-2) rotational branches. (C) 2003 Elsevier Science (USA). All rights reserved.}, keywords = {BAND, ELECTRONIC STATES, NBO, OXIDES, PERTURBATIONS, RESOLUTION, S-STARS, SPECTRA, SYSTEM, VO}, isbn = {0022-2852}, url = {://000184076700010}, author = {Ran, Q. and Tam, W. S. and Cheung, A. S. C. and Merer, A. J.} } @article {648, title = {Revealing system dynamics through decomposition of the perturbation domain in two-dimensional correlation spectroscopy}, journal = {Applied Spectroscopy}, volume = {57}, number = {12}, year = {2003}, note = {ISI Document Delivery No.: 753MHTimes Cited: 5Cited Reference Count: 36}, month = {Dec}, pages = {1551-1560}, type = {Article}, abstract = {A technique is presented to simply and effectively decompose the perturbation domain in two-dimensional (2D) correlation maps calculated on a given set of vibrational spectra. Decomposition of the perturbation domain exposes a wealth of kinetic information complementary to the information extracted from conventional 2D correlation spectroscopy. It is shown that the technique produces "perturbation profile maps" that can be utilized in both the interpretation of the conventional 2D correlation maps and the independent kinetic analysis of the given system. Discrimination between spectral features exhibiting similar, but not identical, dynamics is facilitated by the decomposition, and spectral features exhibiting identical dynamics over the perturbation interval are quickly identified. Spectral features exhibiting similar dynamics over only a sub-range of the full perturbation are also identifiable. Interpretation of phase information illuminated in synchronous and asynchronous maps is simplified. Comparison between similar spectral features present in different samples is facilitated with the technique. The simplicity and ease of implementation of the technique make decomposition of the perturbation domain a valuable addition to the tools available in 2D correlation analysis.}, keywords = {cross-correlation, FT-RAMAN, HUMAN, INFRARED CORRELATION SPECTROSCOPY, multivariate data, POLYACRYLAMIDE GELS, POLYMER GEL DOSIMETERS, RADIATION-DOSIMETRY, Raman spectroscopy, SAMPLE-SAMPLE, SECONDARY STRUCTURE, SERUM-ALBUMIN, SPECTRA, STRUCTURAL-CHANGES, two-dimensional correlation spectroscopy}, isbn = {0003-7028}, url = {://000187234800013}, author = {Jirasek, A. and Schulze, G. and Blades, M. W. and Turner, R. F. B.} } @article {648, title = {Revealing system dynamics through decomposition of the perturbation domain in two-dimensional correlation spectroscopy}, journal = {Applied Spectroscopy}, volume = {57}, number = {12}, year = {2003}, note = {ISI Document Delivery No.: 753MHTimes Cited: 5Cited Reference Count: 36}, month = {Dec}, pages = {1551-1560}, type = {Article}, abstract = {A technique is presented to simply and effectively decompose the perturbation domain in two-dimensional (2D) correlation maps calculated on a given set of vibrational spectra. Decomposition of the perturbation domain exposes a wealth of kinetic information complementary to the information extracted from conventional 2D correlation spectroscopy. It is shown that the technique produces "perturbation profile maps" that can be utilized in both the interpretation of the conventional 2D correlation maps and the independent kinetic analysis of the given system. Discrimination between spectral features exhibiting similar, but not identical, dynamics is facilitated by the decomposition, and spectral features exhibiting identical dynamics over the perturbation interval are quickly identified. Spectral features exhibiting similar dynamics over only a sub-range of the full perturbation are also identifiable. Interpretation of phase information illuminated in synchronous and asynchronous maps is simplified. Comparison between similar spectral features present in different samples is facilitated with the technique. The simplicity and ease of implementation of the technique make decomposition of the perturbation domain a valuable addition to the tools available in 2D correlation analysis.}, keywords = {cross-correlation, FT-RAMAN, HUMAN, INFRARED CORRELATION SPECTROSCOPY, multivariate data, POLYACRYLAMIDE GELS, POLYMER GEL DOSIMETERS, RADIATION-DOSIMETRY, Raman spectroscopy, SAMPLE-SAMPLE, SECONDARY STRUCTURE, SERUM-ALBUMIN, SPECTRA, STRUCTURAL-CHANGES, two-dimensional correlation spectroscopy}, isbn = {0003-7028}, url = {://000187234800013}, author = {Jirasek, A. and Schulze, G. and Blades, M. W. and Turner, R. F. B.} } @article {479, title = {Fourier transform emission spectroscopy of a new (2)Phi-1(2) Delta system of VO}, journal = {Journal of Molecular Spectroscopy}, volume = {211}, number = {2}, year = {2002}, note = {ISI Document Delivery No.: 547WFTimes Cited: 11Cited Reference Count: 39}, month = {Feb}, pages = {279-283}, type = {Article}, abstract = {High-resolution emission spectra of VO have been recorded in the region 3400-19400 cm(-1) using a Fourier transform spectrometer. The molecules were observed from the reaction of VOCl3 with active nitrogen. Two new bands, with origins near 5539.46 and 5551.69 cm(-1), are assigned as the 0-0 bands of the (2)Phi(5/2)-(2)Delta(3/2) and (2)Phi(7/2)-(2)Delta(5/2) spin-orbit components (respectively) of a (2)Phi-1(2)Delta electronic transition of VO. A rotational analysis of both subbands has been carried out and spectroscopic constants have been extracted. The 1(2)Delta state is known from the previous analysis of the near infrared doublet transitions of VO and the new (2)Phi excited state has rotational constants very similar to those of another (2)Phi state observed previously [Merer et al., J. Mol. Spectrosc. 125, 465 (1987)]. (C) 2002 Elsevier Science (USA).}, keywords = {BAND, OXIDES, PERTURBATIONS, ROTATIONAL STRUCTURE, SPECTRA, STATES, TRANSITION}, isbn = {0022-2852}, url = {://000175355100014}, author = {Ram, R. S. and Bernath, P. F. and Davis, S. P. and Merer, A. J.} } @article {558, title = {An NMR approach to structural proteomics}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {99}, number = {4}, year = {2002}, note = {ISI Document Delivery No.: 524UKTimes Cited: 109Cited Reference Count: 28}, month = {Feb}, pages = {1825-1830}, type = {Article}, abstract = {The influx of genomic sequence information has led to the concept of structural proteomics, the determination of protein structures on a genome-wide scale. Here we describe an approach to structural proteomics of small proteins using NMR spectroscopy. Over 500 small proteins from several organisms were cloned, expressed, purified, and evaluated by NMIR. Although there was variability among proteomes, overall 20\% of these proteins were found to be readily amenable to NMR structure determination. NMIR sample preparation was centralized in one facility, and a distributive approach was used for NMR data collection and analysis. Twelve structures are reported here as part of this approach, which allowed us to infer putative functions for several conserved hypothetical proteins.}, keywords = {ASSIGNMENTS, CATH, DOMAIN, PROGRAM, PROTEINS, SPECTRA}, isbn = {0027-8424}, url = {://000174031100016}, author = {Yee, A. and Chang, X. Q. and Pineda-Lucena, A. and Wu, B. and Semesi, A. and Le, B. and Ramelot, T. and Lee, G. M. and Bhattacharyya, S. and Gutierrez, P. and Denisov, A. and Lee, C. H. and Cort, J. R. and Kozlov, G. and Liao, J. and Finak, G. and Chen, L. and Wishart, D. and Lee, W. and McIntosh, L. P. and Gehring, K. and Kennedy, M. A. and Edwards, A. M. and Arrowsmith, C. H.} } @article {335, title = {The power distribution advantage of fiber-optic coupled ultraviolet resonance Raman spectroscopy for bioanalytical and biomedical applications}, journal = {Journal of Raman Spectroscopy}, volume = {33}, number = {7}, year = {2002}, note = {ISI Document Delivery No.: 580KBTimes Cited: 18Cited Reference Count: 51}, month = {Jul}, pages = {503-510}, type = {Article}, abstract = {Fiber-optic coupled ultraviolet resonance Raman spectroscopy (FO-UVRRS) of photosensitive biological samples is discussed in the context of both clinical and basic medical research applications. The fiberoptic probes are designed specifically for resonance Raman spectroscopy and offer a power distribution advantage over conventional focusing UVRR spectrometers that allows the use of higher power levels without increasing the risk of photo-damage. A typical fiber-optic probe using a 600 pm core diameter fiber for illumination of the sample allows an increase in power at the sample of over an order of magnitude while maintaining the same power density, and therefore the same level of safety, as a typical conventional UVRR spectrometer. This allows high-quality spectra to be easily obtained in 10 s. Spectra of representative biological samples using high power levels without damage are presented, including the study of a photosensitive enzyme-substrate system under anaerobic conditions. Copyright (C) 2002 John Wiley Sons, Ltd.}, keywords = {ACTIVATION, AROMATIC-AMINO-ACIDS, BACTERIA, DEEP UV, ENZYMES, LASER EXCITATION, PROBE, SIMPLICITY, SPECTRA, TISSUE}, isbn = {0377-0486}, url = {://000177232800003}, author = {Barbosa, C. J. and Vaillancourt, F. H. and Eltis, L. D. and Blades, M. W. and Turner, R. F. B.} } @article {335, title = {The power distribution advantage of fiber-optic coupled ultraviolet resonance Raman spectroscopy for bioanalytical and biomedical applications}, journal = {Journal of Raman Spectroscopy}, volume = {33}, number = {7}, year = {2002}, note = {ISI Document Delivery No.: 580KBTimes Cited: 18Cited Reference Count: 51}, month = {Jul}, pages = {503-510}, type = {Article}, abstract = {Fiber-optic coupled ultraviolet resonance Raman spectroscopy (FO-UVRRS) of photosensitive biological samples is discussed in the context of both clinical and basic medical research applications. The fiberoptic probes are designed specifically for resonance Raman spectroscopy and offer a power distribution advantage over conventional focusing UVRR spectrometers that allows the use of higher power levels without increasing the risk of photo-damage. A typical fiber-optic probe using a 600 pm core diameter fiber for illumination of the sample allows an increase in power at the sample of over an order of magnitude while maintaining the same power density, and therefore the same level of safety, as a typical conventional UVRR spectrometer. This allows high-quality spectra to be easily obtained in 10 s. Spectra of representative biological samples using high power levels without damage are presented, including the study of a photosensitive enzyme-substrate system under anaerobic conditions. Copyright (C) 2002 John Wiley Sons, Ltd.}, keywords = {ACTIVATION, AROMATIC-AMINO-ACIDS, BACTERIA, DEEP UV, ENZYMES, LASER EXCITATION, PROBE, SIMPLICITY, SPECTRA, TISSUE}, isbn = {0377-0486}, url = {://000177232800003}, author = {Barbosa, C. J. and Vaillancourt, F. H. and Eltis, L. D. and Blades, M. W. and Turner, R. F. B.} } @article {5103, title = {Anomalous vibrational dependence of the rotational and hyperfine parameters in the B-4 Pi-X-4 Sigma(-) transition of NbO}, journal = {Journal of Molecular Spectroscopy}, volume = {207}, number = {1}, year = {2001}, note = {ISI Document Delivery No.: 435ZYTimes Cited: 3Cited Reference Count: 19}, month = {May}, pages = {104-112}, type = {Article}, abstract = {The laser excitation spectrum of jet-cooled NbO in the region 16 000-18 000 cm(-1) has been recorded at high resolution, giving rotational and hyperfine constants for the levels v = 0-3 of the B(4)Pi state and v = 1 of the X(4)Sigma (-) state; zero gaps have also been measured at low resolution for some weaker bands involving higher vibrational levels. Taken together with the laser data for the B-X (0,0) band from Adam et al. (J. Chem. Phys. 94, 6240-6262 (1994)) and the Fourier transform emission data for the doublet manifold from Launila et al. (J. Mol. Spectrosc. 186, 131-143 (1997)), the new data give a very complete picture of the vibrational energy level pattern in this region. Strong irregularities in the vibrational dependences of the B(4)Pi rotational and hyperfine constants can be interpreted in terms of spin-orbit interaction between the B(4)Pi state and the f(2)Pi, c(2)phi, and d(2)Delta states. The interaction is strong enough that all three doublet states can be seen in absorption from the X(4)Sigma (-) ground state, adding to the complexity of the spectrum. The hitherto unknown sigma delta sigma* (4)Delta state is estimated to lie near 17 500 cm(-1), from the change of sign in the spin-rotation parameter gamma of the B(4)Pi state between v = 2 and 3. (C) 2001 Academic Press.}, keywords = {SPECTRA, SPECTROSCOPY, STATE, SYSTEM}, isbn = {0022-2852}, url = {://000168913100016}, author = {Kingston, C. T. and Liao, C. K. D. and Merer, A. J. and Tang, S. J.} } @article {4946, title = {Accurate density-functional calculation of core-electron binding energies of some substituted benzenes}, journal = {Bulletin of the Chemical Society of Japan}, volume = {73}, number = {11}, year = {2000}, note = {ISI Document Delivery No.: 380KRTimes Cited: 7Cited Reference Count: 32}, month = {Nov}, pages = {2453-2460}, type = {Article}, abstract = {The core electron binding energies (CEBE{\textquoteright}s) of benzene, seven monosubstituted benzenes (Ph-X) and one disubstituted benzene (p-NH2-C6H4-NO2) were calculated using density-functional theory (DFT). The unrestricted generalized transition-state (uGTS) model was employed. The DeMon DFT program with a combined functional of Becke{\textquoteright}s exchange (B88) with Perdew{\textquoteright}s correlation (P86) was used. The average absolute deviation of the calculated CEBE{\textquoteright}s of the title compounds was 0.3 eV when the cc-pVDZ basis set was used. The "CEBE shift" of the ring carbon in Ph-X was calculated while taking the CEBE on the ring carbon in Ph-H as a reference. The thus-calculated CEBE shifts agree with experiment within the value of the average absolute deviation, 0.1 eV. The signs and quantitative numerical values of the CEBE shifts are very close to the corresponding Hammett sigma constants.}, keywords = {APPROXIMATION, BORON, DERIVATIVES, GAS, PARAMETERS, RAY PHOTOELECTRON-SPECTROSCOPY, SPECTRA, ZETA BASIS-SET}, isbn = {0009-2673}, url = {://000165701500004}, author = {Takahata, Y. and Chong, D. P.} } @article {4768, title = {Accurate density-functional calculation of core-electron binding energies with a scaled polarized triple-zeta basis set - VII. Effects of poorer geometry and poorer basis sets}, journal = {Journal of Electron Spectroscopy and Related Phenomena}, volume = {106}, number = {1}, year = {2000}, note = {ISI Document Delivery No.: 274BPTimes Cited: 7Cited Reference Count: 40}, month = {Jan}, pages = {1-6}, type = {Article}, abstract = {Our efficient method of calculating accurate core-electron binding energies has been applied to many cases. In order to extend the application to larger systems, such as oligomers and clusters; model polymers; and adsorbates on metals, respectively, the use slightly smaller basis sets and geometry optimized by a semiempirical molecular orbital method such as Austin Model I, without sacrificing accuracy should be aimed for. In this paper, we report the results of our study on the effects of using such poorer geometry and poorer basis sets. (C) 2000 Elsevier Science B.V. All rights reserved.}, keywords = {AFFINITIES, APPROXIMATION, ATOMS, core-electron binding energies, DFT, ESCA, ethyl perfluoroacetate, GAS-PHASE, ISOMERS, MOLECULES, SPECTRA, XPS}, isbn = {0368-2048}, url = {://000084744100001}, author = {Chong, D. P. and Bureau, C.} } @article {4962, title = {Bis(carbonyl)platinum(II) derivatives: Molecular structure of cis-Pt(CO)(2)(SO3F)(2), complete vibrational analysis of cis-Pt(CO)(2)Cl-2, and attempted synthesis of cis-Pt(CO)(2)F-2}, journal = {Inorganic Chemistry}, volume = {39}, number = {20}, year = {2000}, note = {ISI Document Delivery No.: 361DNTimes Cited: 12Cited Reference Count: 91}, month = {Oct}, pages = {4424-4432}, type = {Article}, abstract = {{As part of a comprehensive study of square planar palladium(II) and platinum(II) carbonyl derivatives, the molecular structure of cis-Pt(CO)(2)(SO3F)(2), the complete vibrational spectra of cis-Pt(CO)(2)Cl-2 and the attempted synthesis of cis-Pt(CO)(2)F-2 an reported. cis-Pt(CO)(2)(SO3F)(2) is isostructural with cis-Pd(CO) (2)(SO3F)(2) and crystallizes in the monoclinic space group P2(1)/n (no. 14). Crystal data: a = 7.419(1) Angstrom; b = 14.751(2) Angstrom; c 8.634(1) Angstrom; beta = 89.95(1)degrees; V = 934.9(2) Angstrom(3); Z = 4; T = 300 K; R [F-o > 4 sigma(F-o)] = 0.0447 and wR2 = 0.1097. The internal bond parameters of the cis-Pt(CO)(2)(SO3F)(2) are compared to those of cis-Pd(CO)(2)(SO3F)(2), cis-Pt(CO)(2)Cl-2, and [M(CO)(4)](2+)}, keywords = {CARBONYL-COMPLEXES, CRYSTAL-STRUCTURE, FLUOROSULFATE, HALIDE LIGANDS, INORGANIC, LATE TRANSITION-ELEMENTS, NOBLE-METALS, OLIGOMERS, platinum, SPECTRA, UNDECAFLUORODIANTIMONATE(V)}, isbn = {0020-1669}, url = {://000089707500008}, author = {von Ahsen, B. and Wartchow, R. and Willner, H. and Jonas, V. and Aubke, F.} } @article {4991, title = {Laser-induced phosphorescence of SO2 in solid neon: Direct observation of the (b)over-tilde(3)A(2) state in the (OSO)-O-16-O-18 molecule}, journal = {Journal of Physical Chemistry A}, volume = {104}, number = {4}, year = {2000}, note = {ISI Document Delivery No.: 280WFTimes Cited: 13Cited Reference Count: 41}, month = {Feb}, pages = {771-776}, type = {Article}, abstract = {Laser excitation of isotopically labeled SO2 molecules in a neon matrix has allowed the measurement of dispersed phosphorescence spectra ((a) over tilde(3)B(1)-(X) over tilde(1)A(1)) in the wavelength region 387.5-526.3 nm (19 000-25 800 cm(-1)). The origin of the (a) over tilde-(X) over tilde transition lies at 25 747 cm(-1) in (OSO)-O-16-O-16, shifted 18 cm(-1) to the red from the gas phase; the three vibrational frequencies of the (X) over tilde state are nearly unperturbed in the neon matrix (1149, 520, and 1362 cm(-1)). As the zero-phonon lines are sharp and well resolved, it has been possible to monitor emission from a specific isotopomer to obtain its excitation spectrum. The excitation spectra of matrix-isolated (OSO)-O-16-O-16 and (OSO)-O-18-O-18 in the region 350.9-388.5 nm (25 740-28 500 cm(-1)) are similar to those previously observed in the gas phase, with strong perturbations affecting all vibrational levels above a(3)B(1)(110) at 27 005 cm(-1) (370 nm). Two additional groups of bands are observed for the unsymmetrical isotopomer (OSO)-O-18-O-16; they are identified as transitions to levels of the (a) over tilde(3)B(1) state with v(3) = 1 and as direct transitions to the (b) over tilde(3)A(2) state, which both become allowed in the lower symmetry. The v(3) frequency of the (a) over tilde(3)B(1) state of (OSO)-O-18-O-16 is 922 cm(-1); for the (b) over tilde(3)A(2) state, v(1) similar or equal to 791 cm(-1) and v(2) similar or equal to 315 cm(-1), while the (b) over tilde (001) level lies 26 653 cm(-1) above the (X) over tilde (000) level.}, keywords = {ABSORPTION, BAND SYSTEM, FLUORESCENCE, INDUCED EMISSION, MATRICES, REGION, ROTATIONAL, SPECTRA, STRUCTURE, SULFUR-DIOXIDE, VIBRATIONAL STRUCTURE}, isbn = {1089-5639}, url = {://000085126200014}, author = {Zen, C. C. and Chen, I. C. and Lee, Y. P. and Merer, A. J.} } @article {4549, title = {Characterization of Na5P3O10 polymorphs by Na-23 MAS, Na-23 MQMAS, and P-31 MAS NMR spectroscopy}, journal = {Inorganic Chemistry}, volume = {38}, number = {1}, year = {1999}, note = {ISI Document Delivery No.: 157MUTimes Cited: 20Cited Reference Count: 42}, month = {Jan}, pages = {84-92}, type = {Article}, abstract = {The two anhydrous polymorphs of Na5P3O10 have been characterized by Na-23 and P-31 MAS NMR spectroscopy, The Na-23 multiple-quantum (MQ) MAS NMR spectrum of the low-temperature form (phase II) displays three resonances for which the quadrupole coupling parameters and isotropic chemical shifts have been accurately determined from the MAS NMR spectra of the central transition. Thereby, discrepancies between recently reported Na-23 MQMAS spectra of this phase and the crystal structure have been clarified. The Na-23 resonances observed for the low-temperature form are assigned to the crystallographically nonequivalent Na sites in the crystal structure using point-monopole calculations of the electric-field gradient tensors. Three Na-23 resonances have also been observed for the high-temperature form (phase I), with two signals having very similar quadrupolar couplings and isotropic chemical shifts indicating similar coordination environments for the corresponding Na sites, in disagreement with the reported single-crystal structure. Point-monopole calculations of the electric-field gradient tensors based on the crystal structure fail to reproduce the experimental values. The P-31 chemical shielding anisotropies, obtained from P-31 MAS NMR spectra, show that the terminal P atoms of the P3O105- ions have a negative shielding anisotropy parameter (delta(sigma) = delta(iso) - delta(33)) in agreement with similar observations reported for diphosphates. This characteristic feature has been used in the assignment of the three P-31 resonances observed for the hexahydrate Na5P3O10. 6H(2)O.}, keywords = {2-SPIN SYSTEMS, ANGLE-SPINNING NMR, CHEMICAL SHIELDING, CONDENSED PHOSPHATES, DIPOLAR, NUCLEAR-MAGNETIC-RESONANCE, QUADRUPOLAR NUCLEI, SODIUM TRIPHOSPHATE, SOLID-STATE, SPECTRA, TENSORS}, isbn = {0020-1669}, url = {://000078066900013}, author = {Fyfe, C. A. and Altenschildesche, H. M. Z. and Skibsted, J.} } @article {4692, title = {Fourier transform microwave spectroscopy of AlBr}, journal = {Journal of Molecular Spectroscopy}, volume = {193}, number = {1}, year = {1999}, note = {ISI Document Delivery No.: 151JTTimes Cited: 7Cited Reference Count: 7}, month = {Jan}, pages = {224-227}, type = {Article}, keywords = {ROTATION, SPECTRA, SPIN INTERACTIONS}, isbn = {0022-2852}, url = {://000077717500019}, author = {Walker, K. A. and Gerry, M. C. L.} } @article {4676, title = {NMR and molecular structure of partially oriented mono and para methyl- and chlorobenzenes dissolved in nematic liquid crystals}, journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie}, volume = {77}, number = {11}, year = {1999}, note = {ISI Document Delivery No.: 253FETimes Cited: 8Cited Reference Count: 69}, month = {Nov}, pages = {1761-1774}, type = {Article}, abstract = {Spectral parameters, order parameters, and structural parameters, including the vibrationally corrected r(alpha) structure of the partially oriented solutes p-xylene, p-chlorotoluene, p-dichlorobenzene, toluene, and chlorobenzene dissolved in three liquid crystal mixtures, are reported. For samples containing the three solutes p-xylene, p-dichlorobenzene, and 1,3,5-trichlorobenzene, multiple quantum (MQ) nuclear magnetic resonance was used to aid in the analysis of the complex high-resolution spectra of the g-xylene. The high-resolution spectra of 1,3,5-trichlorobenzene and p-dichlorobenzene were easily identified and analyzed once the calculated p-xylene spectrum was subtracted from the experimental one. The methyl groups of p-xylene, p-chlorotoluene, and toluene have similar geometries when the structure is determined from dipolar couplings corrected for harmonic vibrations.}, keywords = {ELECTRIC-DIPOLE INTERACTIONS, EXCITATION, H-2 NMR, MAGNETIC-RESONANCE, MEAN TORQUE, molecular structure, MULTIPLE-QUANTUM NMR, nematic liquid crystal, NMR, ORDER MATRIX, order parameter, SELECTIVE, SOLUTES, SOLVENTS, SPECTRA}, isbn = {0008-4042}, url = {://000083545300009}, author = {Syvitski, R. T. and Burnell, E. E.} } @article {4573, title = {The Norrish type II reaction in the crystalline state: Toward a better understanding of the geometric requirements for gamma-hydrogen atom abstraction}, journal = {Tetrahedron}, volume = {55}, number = {4}, year = {1999}, note = {ISI Document Delivery No.: 159BRTimes Cited: 69Cited Reference Count: 58}, month = {Jan}, pages = {885-907}, type = {Article}, abstract = {By correlating the success or failure of the Norrish type II reaction for a series of compounds in the crystalline state with geometric data derived from X-ray crystallography (the so-called Crystal Structure-Solid State Reactivity Method), the distance and angular requirements for photochemical gamma-hydrogen atom abstraction have been established. These studies indicate that abstractions are preferred when the C=O ... H-gamma, distance is close to the sum of the van der Waals radii of hydrogen and oxygen (2.72 Angstrom), and that the gamma-hydrogen atom can deviate by as much as 50-60 degrees from the plane containing the oxygen n-orbital responsible for abstraction. Because molecular conformations and interatomic distances and angles can be calculated readily by using empirical force field methods, such data permit predictions to be made concerning the outcome of hypothetical Norrish type II processes. (C) 1999 Elsevier Science Ltd. All rights reserved.}, keywords = {ABSOLUTE ASYMMETRIC-SYNTHESIS, CONFORMATIONAL CONTROL, ENVIRONMENT, KETONES, METHODOLOGY, MOLECULES, PHOTOCHEMISTRY, PHOTOCYCLIZATION, SOLID-STATE, SPECTRA}, isbn = {0040-4020}, url = {://000078152400001}, author = {Ihmels, H. and Scheffer, J. R.} } @article {4313, title = {Unfolding of proteins monitored by electrospray ionization mass spectrometry: A comparison of positive and negative ion modes}, journal = {Journal of the American Society for Mass Spectrometry}, volume = {9}, number = {12}, year = {1998}, note = {ISI Document Delivery No.: 141FPTimes Cited: 72Cited Reference Count: 56}, month = {Dec}, pages = {1248-1254}, type = {Article}, abstract = {Electrospray ionization (ESI) mass spectrometry (MS) in both the positive and negative ion mode has been used to study protein unfolding transitions of lysozyme, cytochrome c (cyt c), and ubiquitin in solution. As expected, ESI of unfolded lysozyme leads to the formation of substantially higher charge states than the tightly folded protein in both modes of operation. Surprisingly, the acid-induced unfolding of cyt c as well as the acid and the base-induced unfolding of ubiquitin show different behavior: In these three cases protein unfolding only leads to marginal changes in the negative ion charge state distributions, whereas in the positive ion mode pronounced shifts to higher charge states are observed. This shows that ESI MS in the negative ion mode as a method for probing conformational changes of proteins in solution should be treated with caution. The data presented in this work provide further evidence that the conformation of a protein in solution not its charge state is the predominant factor for determining the ESI charge slate distribution in the positive ion mode. Furthermore, these data support the hypothesis of a recent study (Konermann and Douglas, Biochemistry 1997, 36, 12296-12302) which suggested that ESI in the positive ion mode is not sensitive to changes in the secondary structure of proteins but only to changes in the tertiary structure. (C) 1998 American Society for Mass Spectrometry.}, keywords = {A-STATE, BINDING, CIRCULAR-DICHROISM, CYTOCHROME-C, HYDROGEN-DEUTERIUM EXCHANGE, INDUCED CONFORMATIONAL-CHANGES, MYOGLOBIN, NUCLEAR-MAGNETIC-RESONANCE, SITES, SPECTRA, UBIQUITIN}, isbn = {1044-0305}, url = {://000077132600002}, author = {Konermann, L. and Douglas, D. J.} } @article {4028, title = {Cytochrome c folding kinetics studied by time-resolved electrospray ionization mass spectrometry}, journal = {Biochemistry}, volume = {36}, number = {18}, year = {1997}, note = {ISI Document Delivery No.: WY063Times Cited: 82Cited Reference Count: 46}, month = {May}, pages = {5554-5559}, type = {Article}, abstract = {A new method for studying the folding kinetics of proteins is described. The method combines a continuous flow mixing technique with an electrospray mass spectrometer. Different protein conformations in solution are detected by the different charge states they produce during electrospray ionization. Unfolded proteins generally have more accessible protonation sites and give higher charge states than native proteins. The method is applied to study the refolding of acid-denatured cytochrome c. Global data analysis is used to obtain the exponential lifetimes which are associated with the refolding process. The kinetics can be described by two lifetimes of 0.17 +/- 0.02 and 8.1 +/- 0.9 s which are in accordance with the results of stopped flow experiments previously described in the literature. These lifetimes are associated with roughly 90 and 10\% of the total intensity changes in the mass spectrum, respectively, and most likely reflect fast and slow refolding subpopulations of cytochrome c in solution.}, keywords = {COMPLEX, denaturation, FERRICYTOCHROME-C, IRON BLEOMYCIN, LIGANDS, MECHANISM, PATHWAYS, PROBING CONFORMATIONAL-CHANGES, PROTEINS, SPECTRA}, isbn = {0006-2960}, url = {://A1997WY06300029}, author = {Konermann, L. and Collings, B. A. and Douglas, D. J.} } @article {3960, title = {Hyperfine coupling constants of muonium-substituted cyclohexadienyl radicals in the gas phase: C(6)H(6)Mu, C(6)D(6)Mu, C(6)F(6)Mu}, journal = {Applied Magnetic Resonance}, volume = {13}, number = {1-2}, year = {1997}, note = {ISI Document Delivery No.: YE729Times Cited: 13Cited Reference Count: 33}, pages = {181-194}, type = {Article}, abstract = {Muon spin rotation (mu SR) and avoided level crossing resonance (ALCR) have been used to determine the hyperfine coupling constants (hfcs) of the muonium-substituted cyclohexadienyl radicals C(6)H(6)Mu, C(6)D(6)Mu and C(6)F(6)Mu in the gas phase, at pressures similar to 1 and 15 atm and temperatures in the range 40-80 degrees C. Equivalent studies of polyatomic free radicals in gases, by electron spin resonance (ESR) spectroscopy, are generally not possible in this pressure range. The present gas phase results support the findings of earlier studies of cyclohexadienyl radicals in the condensed phase, by both mu SR and ESR. Minor but not insignificant (similar to 1\%) effects on the hfcs are observed, which can be qualitatively understood for such nonpolar media in terms of their differing polarizabilities. This is the first time that comparisons of this nature have been possible between different phases at the same temperatures. These mu SR/ALCR gas-phase results provide a valuable benchmark for computational studies on radicals, free from possible effects of solvent or matrix environments.}, keywords = {ETHYL RADICALS, LEVEL-CROSSING SPECTROSCOPY, ORGANIC FREE-RADICALS, RESONANCE, SPECTRA, SPIN ROTATION}, isbn = {0937-9347}, url = {://A1997YE72900015}, author = {Fleming, Donald G. and Arseneau, D. J. and Pan, J. J. and Shelley, M. Y. and Senba, M. and Percival, P. W.} } @article {4148, title = {Microwave Fourier transform spectroscopy of magnesium sulfide produced by laser ablation}, journal = {Journal of Molecular Spectroscopy}, volume = {182}, number = {1}, year = {1997}, note = {ISI Document Delivery No.: WN854Times Cited: 64Cited Reference Count: 11}, month = {Mar}, pages = {178-183}, type = {Article}, abstract = {The pure rotational spectrum of magnesium sulfide has been measured with a cavity pulsed microwave Fourier transform (MWFT) spectrometer, as a test of a new laser ablation source. The J = 1-0 transition near 16 GHz has been measured for 4 isotopomers in the ground vibrational slate, as well as for the main isotopomer, (MgS)-Mg-24-S-32, in the first excited vibrational state. Mg-25 nuclear hyperfine structure has been observed and the nuclear quadrupole coupling constant, eQq(Mg-25), has been determined. A value for the equilibrium bond length has been obtained. (C) 1997 Academic Press.}, keywords = {MGS, SPECTRA}, isbn = {0022-2852}, url = {://A1997WN85400017}, author = {Walker, K. A. and Gerry, M. C. L.} } @article {4130, title = {The quadrature discretization method (QDM) in the calculation of the rotational-vibrational transitions in rare gas dimers}, journal = {Theochem-Journal of Molecular Structure}, volume = {391}, number = {1-2}, year = {1997}, note = {ISI Document Delivery No.: WU757Times Cited: 3Cited Reference Count: 38}, month = {Feb}, pages = {131-139}, type = {Article}, abstract = {A discretization method referred to as the Quadrature Discretization Method (QDM) is employed for the determination of the rotational-vibrational states of the inert gas dimers. The QDM is based on the discretization of the wave function on a grid of points that coincide with the points of a quadrature. The quadrature is based on a set of non-classical polynomials orthogonal with respect to a weight function determined by the potential function in the Schroedinger equation. In this paper, the weight functions used in the solution of the Schroedinger equation are related to the ground state wavefunctions of the Morse potential that approximates the potential of interest. Calculations are carried out for vibrational energy levels for HF modelled with a Morse potential. Excellent agreement is obtained with the known spectrum of the Morse potential. The rate of convergence of the eigenvalues and the eigenfunctions of the Schroedinger equation is very rapid with this approach. The vibrational and rotational transitions for the rare gas dimers are calculated and compared with the results reported recently by Ogilvie and Wang (J. Mol. Struc., 291 (1993) 313). (C) 1997 Elsevier Science B.V.}, keywords = {AR-XE, COEFFICIENTS, DISCRETE-VARIABLE REPRESENTATION, NE-KR, ORDINATE METHOD, POTENTIALS, quadrature discretion method, QUANTUM-MECHANICS, rare gas dimer, rotation-vibration, SCHRODINGER-EQUATION, Schroedinger equation, SPECTRA, STATES, TRANSITION}, isbn = {0166-1280}, url = {://A1997WU75700014}, author = {Shizgal, B. D.} } @article {4070, title = {Stereospecific assignment of the NH2 resonances from the primary amides of asparagine and glutamine side chains in isotopically labeled proteins}, journal = {Journal of Biomolecular Nmr}, volume = {9}, number = {3}, year = {1997}, note = {ISI Document Delivery No.: XF937Times Cited: 18Cited Reference Count: 33}, month = {Apr}, pages = {306-312}, type = {Article}, abstract = {An HMQC-based pulse scheme is presented for the stereospecific assignment of asparagine and glutamine side-chain amide protons. The approach makes use of the recently developed quantitative-J correlation spectroscopy [Bar, A. et al. (1994) Methods Enzymol., 239, 79-105] to distinguish the E and Z primary amide protons and, as such, eliminates the need for assignments derived from more time-consuming and potentially ambiguous NOE methods. An application of this method to a uniformly N-15,C-13-labeled cellulose-binding domain is presented. When used in combination with a NOESY-HSQC experiment, the predominant chi(2) dihedral angles of two asparagine side chains in this protein can also be defined.}, keywords = {ANGLE, BACKBONE AMIDE, C-13 MAGNETIZATION, dihedral, EXCITATION, H-1, HMQC spectroscopy, LARGER PROTEINS, N-15, NMR, primary amide, SATURATION, SPECTRA, SPECTROSCOPY, STEREOSPECIFIC ASSIGNMENT}, isbn = {0925-2738}, url = {://A1997XF93700008}, author = {McIntosh, L. P. and Brun, E. and Kay, L. E.} } @article {3901, title = {Synthesis and spectroscopic characterization of hexakis(carbonyl)iron(II) undecafluorodiantimonate(V), [Fe(CO)(6)][Sb2F11](2)}, journal = {Inorganic Chemistry}, volume = {36}, number = {2}, year = {1997}, note = {ISI Document Delivery No.: WC887Times Cited: 20Cited Reference Count: 27}, month = {Jan}, pages = {158-160}, type = {Article}, abstract = {{Oxidative carbonylation of Fe(CO)(5) in liquid SbF5 and a CO atmosphere, with either AsF5 or Cl-2 as external oxidizing agents, produces [Fe(CO)(6)][Sb2F11](2) in very high yield. The resulting off-white solid material is thermally stable (above 200 degrees C). The homoleptic carbonyl cation [Fe(CO)(6)](2+), the first of its type formed by a 3d-metal, is isostructural with [Ru(CO)(6)](2+) and [Os(CO)(6)](2+) which are obtained by reductive carbonylation of M(SO3F)(3)}, keywords = {SPECTRA}, isbn = {0020-1669}, url = {://A1997WC88700007}, author = {Bley, B. and Willner, H. and Aubke, F.} } @article {3940, title = {Why ALC mu SR is superior for gas-phase radical spectroscopy}, journal = {Hyperfine Interactions}, volume = {106}, number = {1-4}, year = {1997}, note = {ISI Document Delivery No.: XB055Times Cited: 9Cited Reference Count: 147th International Conference on Muon Spin Rotation, Relaxation, ResonanceAPR 15-19, 1996NIKKO, JAPANUniv Tokyo, Meson Sci Lab, Inst Phys \& Chem Res, Muon Sci Lab}, pages = {137-142}, type = {Proceedings Paper}, abstract = {ALC mu SR spectra of the muonated ethyl and cyclohexadienyl radicals in the gas phase are reported. They have surprisingly narrow lines for a magnetic resonance type technique under conditions near ambient temperature and near 1 atmosphere pressure. The main reason for this behaviour is the dramatic reduction of electron spin relaxation in high magnetic fields.}, keywords = {HYPERFINE CONSTANTS, ORGANIC FREE-RADICALS, SPECTRA, SPIN RELAXATION}, isbn = {0304-3843}, url = {://A1997XB05500019}, author = {Dilger, H. and Roduner, E. and Stolmar, M. and Reid, I. D. and Fleming, Donald G. and Arseneau, D. J. and Pan, J. J. and Senba, M. and Shelley, M.} } @article {3650, title = {Addition kinetics and spin exchange in the gas phase reaction of the ethyl radical with oxygen}, journal = {Journal of Physical Chemistry}, volume = {100}, number = {16}, year = {1996}, note = {ISI Document Delivery No.: UF879Times Cited: 21Cited Reference Count: 58}, month = {Apr}, pages = {6561-6571}, type = {Article}, abstract = {The kinetics of the addition reaction of O-2 to the ethyl radical has been investigated as a function of temperature (259-425 K) and pressure (1.5-60 bar) using the muon spin relaxation technique in longitudinal magnetic fields. Within this temperature range at 1.5 bar, the chemical reaction is represented by an Arrhenius rate law with an activation energy of -4.4(4) kJ mol(-1) and an apparent frequency factor of 1.3(2) x 10(-12) cm(3) molecule(-1) s(-1). The high-pressure limit of the rate constant at 294 K amounts to k(ch)(infinity) = 8.7(8) x 10(-12) cm(3) molecule(-1) s(-1). Within error, this limit has been reached at 1.5 bar. The rate coefficient for spin exchange, k(ex) = 2.8(2) x 10(-10) cm(3) molecule(-1) s(-1), is collision controlled. The results for k(ch) agree well with experimental literature values, but the temperature dependence is more pronounced than that predicted on the basis of a RRKM extrapolation from low-pressure data. The theoretical basis for the analysis of experimental data is given, and the results are discussed.}, keywords = {DEPENDENCE, DYNAMICS, LIQUIDS, muonium, O-2, PARAMETERS, RANGE, RATE CONSTANTS, relaxation, SPECTRA}, isbn = {0022-3654}, url = {://A1996UF87900032}, author = {Dilger, H. and Schwager, M. and Tregennapiggott, P. L. W. and Roduner, E. and Reid, I. D. and Arseneau, D. J. and Pan, J. J. and Senba, M. and Shelley, M. and Fleming, Donald G.} } @article {3597, title = {Cationic iridium(III) carbonyl complexes: [Ir(CO)(6)](3+) and [Ir(CO)(5)Cl](2+)}, journal = {Angewandte Chemie-International Edition in English}, volume = {35}, number = {17}, year = {1996}, note = {ISI Document Delivery No.: VM029Times Cited: 55Cited Reference Count: 27}, month = {Sep}, pages = {1974-1976}, type = {Article}, keywords = {carbonyl complexes, ELUCIDATION, FLUOROSULFATE, IR spectroscopy, iridium compounds, MOLECULAR-STRUCTURE, MONOXIDE, SPECTRA, STRUCTURE, UNDECAFLUORODIANTIMONATE(V)}, isbn = {0570-0833}, url = {://A1996VM02900023}, author = {Bach, C. and Willner, H. and Wang, C. Q. and Rettig, S. J. and Trotter, J. and Aubke, F.} } @article {3597, title = {Cationic iridium(III) carbonyl complexes: [Ir(CO)(6)](3+) and [Ir(CO)(5)Cl](2+)}, journal = {Angewandte Chemie-International Edition in English}, volume = {35}, number = {17}, year = {1996}, note = {ISI Document Delivery No.: VM029Times Cited: 55Cited Reference Count: 27}, month = {Sep}, pages = {1974-1976}, type = {Article}, keywords = {carbonyl complexes, ELUCIDATION, FLUOROSULFATE, IR spectroscopy, iridium compounds, MOLECULAR-STRUCTURE, MONOXIDE, SPECTRA, STRUCTURE, UNDECAFLUORODIANTIMONATE(V)}, isbn = {0570-0833}, url = {://A1996VM02900023}, author = {Bach, C. and Willner, H. and Wang, C. Q. and Rettig, S. J. and Trotter, J. and Aubke, F.} } @article {3697, title = {Density functional computations for inner-shell excitation spectroscopy}, journal = {Chemical Physics Letters}, volume = {262}, number = {6}, year = {1996}, note = {ISI Document Delivery No.: VV284Times Cited: 28Cited Reference Count: 29}, month = {Nov}, pages = {729-732}, type = {Article}, abstract = {The 1s {\textendash}> pi* inner-shell excitation spectra of seven molecules have been studied using density functional theory along with the unrestricted generalized transition state (uGTS) approach. The exchange-correlation potential is based on a combined functional of Becke{\textquoteright}s exchange (B88) and Perdew{\textquoteright}s correlation (P86). A scaling procedure based on Clementi and Raimondi{\textquoteright}s rules for atomic screening is applied to the cc-pVTZ basis set of atoms where a partial core-hole is created in the uGTS calculations. The average absolute deviation between our predicted 1s {\textendash}> pi* excitation energies and experimental values is only 0.16 eV. Singlet-tripler splittings of C 1s {\textendash}> pi* transitions of CO, C2H2, C2H4, and C6H6 also agree with experimental observations. The average absolute deviation of our predicted core-electron binding energies and term values is 0.23 and 0.29 eV, respectively.}, keywords = {APPROXIMATION, ATOMS, CORE, ELECTRON BINDING-ENERGIES, GAS, MODEL, MOLECULES, SPECTRA, VALENCE-SHELL}, isbn = {0009-2614}, url = {://A1996VV28400009}, author = {Hu, C. H. and Chong, D. P.} } @article {3630, title = {A multiple-quantum H-1 NMR study of conformational biasing of biphenyl in a nematic liquid crystal}, journal = {Journal of Magnetic Resonance Series A}, volume = {118}, number = {2}, year = {1996}, note = {ISI Document Delivery No.: TZ082Times Cited: 24Cited Reference Count: 42}, month = {Feb}, pages = {264-271}, type = {Article}, abstract = {Multiple-quantum H-1 NMR spectroscopy was used to simplify the analysis of the complicated one-quantum spectrum of the 10-spin molecule biphenyl dissolved in a nematic solvent. An eight-quantum spectrum was analyzed to obtain estimates of all dipolar coupling constants and chemical shifts, which were used as a starting point to solve the one-quantum spectrum, The dipolar couplings from the one-quantum spectrum were used, in combination with those determined in a previous study using different liquid-crystal solvents, to obtain vibrationally corrected geometrical parameters and orientational order parameters, The effective internal rotational potential was found to be shifted slightly toward a more planar configuration relative to the gas-phase potential, with an equilibrium dihedral angle of 37 degrees. (C) 1996 Academic Press, Inc.}, keywords = {BARRIER, DERIVATIVES, GASEOUS, INTERNAL-ROTATION, MIXTURES, MOLECULAR-STRUCTURE, PERDEUTERATED BIPHENYL, SOLVENTS, SPECTRA, SPECTROSCOPY, STATE}, isbn = {1064-1858}, url = {://A1996TZ08200013}, author = {Chandrakumar, T. and Polson, J. M. and Burnell, E. E.} } @article {3716, title = {NMR, MS and X-ray crystal structure determination of the bixin family of apocarotenoids}, journal = {Journal of Chemical Research-S}, number = {10}, year = {1996}, note = {ISI Document Delivery No.: VT903Times Cited: 4Cited Reference Count: 70}, month = {Oct}, pages = {446-\&}, type = {Article}, abstract = {The assignment of the H-1 and C-13 NMR spectra of alpha-bixin, methyl alpha-bixin, beta-bixin and methyl beta-bixin have been carried out using a combination of one- and two-dimensional techniques; the FAB(+) mass spectra of all these bixins had the molecular ion and methyl tropylium as high abundance peaks; also, the structures of alpha-bixin and methyl alpha-bixin have been confirmed by X-ray crystal structure determinations.}, keywords = {ALL-TRANS, ANNATTO, ASSIGNMENTS, BETA-CAROTENE, COMPLETE H-1, FAST-ATOM-BOMBARDMENT, ORELLANA, SPECTRA, TANDEM MASS-SPECTROMETRY, THERMAL-DEGRADATION}, isbn = {0308-2342}, url = {://A1996VT90300006}, author = {Kelly, D. R. and Edwards, A. A. and Parkinson, J. A. and Olovsson, G. and Trotter, J. and Jones, S. and Malik, K. M. A. and Hursthouse, M. B. and Hibbs, D. E.} } @article {3819, title = {Structural coupling of the inhibitory regions flanking the ETS domain of murine Ets-1}, journal = {Protein Science}, volume = {5}, number = {2}, year = {1996}, note = {ISI Document Delivery No.: TU724Times Cited: 46Cited Reference Count: 66}, month = {Feb}, pages = {296-309}, type = {Article}, abstract = {Several members of the ets gene family of transcription factors show negative regulation of DNA binding by intramolecular interactions. A structural mechanism for this auto-inhibition is investigated using a 161-residue N-terminal deletion mutant of murine Ets-1, Ets-1 Delta N280. This protein shows a similar reduced affinity for DNA as native Ets-1 because it contains the ETS domain in context of the flanking amino- and carboxy-terminal regions that together mediate repression of DNA binding. The secondary structure of Ets-1 Delta N280 was determined using NMR chemical shift, NOE, J coupling, and amide hydrogen exchange information. In addition to the winged helix-turn-helix ETS domain, Ets-1 Delta N280 contains two alpha-helices in the amino-terminal inhibitory region and one alpha-helix in the carboxy-terminal inhibitory region. Chemical shift comparisons were made between this protein and an activated form of Ets-1 lacking the amino-terminal inhibitory region. The spectral differences demonstrate that the amino- and carboxy-terminal inhibitory sequences are structurally coupled to one another, thus explaining the observation that both regions are required for the repression of DNA binding. Furthermore, these data show that the inhibitory sequences also interact directly with the first helix of the intervening ETS domain, thereby providing a pathway for the repression of DNA binding. These results lead to a model of an inhibitory module in Ets-1 composed of both the amino- and carboxy-terminal regions interfaced with the ETS domain. This establishes the structural framework for understanding the intramolecular inhibition of Ets-1 DNA binding.}, keywords = {3-DIMENSIONAL NMR-SPECTROSCOPY, allosteric, ASSIGNMENT, CRYSTAL-STRUCTURE, DNA binding, DNA-BINDING MOTIF, ETS domain, Ets-1 and Ets-2, FACTORS, H-1, INHIBITION, INTRAMOLECULAR, LARGER PROTEINS, N-15 NMR, NMR, protein structure, SPECTRA, transcription, V-ETS, winged helix-turn-helix}, isbn = {0961-8368}, url = {://A1996TU72400014}, author = {Skalicky, J. J. and Donaldson, L. W. and Petersen, J. M. and Graves, B. J. and McIntosh, L. P.} } @article {3705, title = {Substitution reaction mechanisms of dihydrido-ruthenium(II) phosphine complexes: Hydride basicity and molecular hydrogen intermediates}, journal = {Inorganica Chimica Acta}, volume = {250}, number = {1-2}, year = {1996}, note = {ISI Document Delivery No.: VV296Times Cited: 8Cited Reference Count: 43}, month = {Sep}, pages = {351-357}, type = {Article}, abstract = {{Kinetic and activation parameter data for the reactions of cct-Ru(H)(2)(CO)(2)(PPh(3))(2) (1) (cct = cis, cis, trans) in THF with thiols, CO and PPh(3) to give cct-RuH(SR)(CO)(2)(PPh(3))(2), Ru(CO)(3)(PPh(3))(2) and Ru(CO)(2)(PPh(3))(2), respectively, reveal a common, rate-determining step, the initial dissociation of H-2 from 1; the activated complex probably resembles the corresponding Ru(eta(2)-H-2) species. Reaction of Ru(H)(2)(dppm)(2) (2) (as a cis/trans mixture}, keywords = {ACIDITY, CATALYSIS, dihydrogen complexes, ETA-2-DIHYDROGEN COMPLEXES, hydride complexes, HYDRODESULFURIZATION, iron, kinetics and mechanism, MERCAPTO, molecular hydrogen complexes, ruthenium, ruthenium complexes, SPECTRA, sulfide}, isbn = {0020-1693}, url = {://A1996VV29600040}, author = {Jessop, P. G. and Rastar, G. and James, Brian R.} } @article {3610, title = {Synthesis and spectroscopic characterization of bis(trifluorophosphinyl)-gold(I) undecafluorodiantimonate(V) [Au(PF3)(2)][Sb2F11]}, journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie}, volume = {74}, number = {11}, year = {1996}, note = {ISI Document Delivery No.: WC124Times Cited: 3Cited Reference Count: 20}, month = {Nov}, pages = {2392-2394}, type = {Article}, abstract = {The synthesis of [Au(PF3)(2)][Sb2F11], the first trample of a linear, thermally stable metal bis(trifluorophosphine) complex is achieved by CO substitution of [Au(CO)(2)][Sb2F11] by PF3. The [A(PF3)(2)](+) cation can also be generated by reductive phosphorylation by an excess of PF3 in fluorosulfuric acid. Spectroscopic characterization involves F-19 and P-31 NMR in HSO3F and SO2 solution including spectral simulation by the WIN-DAISY method and FT-IR and Raman spectra. Spectroscopic evidence suggests that the metal-ligand bond involves predominantly sigma-bonding with drastically reduced pi-back-donation.}, keywords = {CHEMISTRY, F-19 NMR, gold(I) complex, gold(I) PF3 complex, linear, P-31 NMR, SPECTRA, vibrational spectra}, isbn = {0008-4042}, url = {://A1996WC12400054}, author = {Bley, B. and Bodenbinder, M. and Balzer, G. and Willner, H. and Hagele, G. and Mistry, F. and Aubke, F.} } @article {3313, title = {ANALYSIS OF VALENCE XPS OF (CH2-CHR)(N) (R=H, CH3, OH AND F), (CH2-CH2-NH)(N) AND (CH2-CH2-O)(N) POLYMERS BY THE SEMIEMPIRICAL HAM/3 MO METHOD USING THE N-MER (N=2, 3, 4, 5) MODEL}, journal = {Journal of Physics and Chemistry of Solids}, volume = {56}, number = {8}, year = {1995}, note = {ISI Document Delivery No.: RF331Times Cited: 26Cited Reference Count: 50}, month = {Aug}, pages = {1131-1140}, type = {Article}, abstract = {The valence X-ray photoelectron spectra (XPS) of six representative polymers [CH2-CHR)(n) (R = H, CH3, OH, F), (CH2-CH2-NH)(n), and (CH2-CH2-O)(n)] were analysed by a semi empirical HAM/3 MO method using model molecules [H-(CH2-CHR)(n)-H, (R = H, CH3, OH, F), H2N-(CH2-CH2-NH)(n)-H, and HO-(CH2-CH2-O)(n)-H] with n = 2 to 5. The calculated AlK alpha photo electron spectra were obtained using Gaussian functions of an approximate linewidth (0.10I(k)); I-k = I{\textquoteright}(k) - WD, where I{\textquoteright}(k); is the vertical ionization potential (VIP) of each MO and WD is a shift to account for sample work function, polarization energy and other effects. To explain the broader linewidth for the inner valence spectra, we propose that the lifetime of the 2s hole states are shorter because the holes can be filled by 2p electrons in ultra-violet emission or radiationless transition. The theoretical spectra showed good agreement with the observed spectra of the polymers between 0-40 eV. The present results suggest that the spectra can be analysed by the calculations for model trimers.}, keywords = {BAND, CLUSTER-EXPANSION, Electronic Structure, ELECTRONIC-STRUCTURE, ENERGY-LEVELS, ESCA, IONIZATION, photoelectron spectroscopy, POLYETHYLENE, POLYMERS, POLYOXYMETHYLENE, RAY PHOTOELECTRON-SPECTROSCOPY, SPECTRA, WAVEFUNCTION}, isbn = {0022-3697}, url = {://A1995RF33100017}, author = {Endo, K. and Kaneda, Y. and Aida, M. and Chong, D. P.} } @article {3581, title = {ANTIMONY(III) FLUORIDE FLUOROSULFATES - SYNTHESES AND MOLECULAR-STRUCTURES OF ANTIMONY(III) DIFLUORIDE FLUOROSULFATE [SBF2(SO3F)](X), ANTIMONY(III) FLUORIDE BIS(FLUOROSULFATE) [SBF(SO3F)(2)](X), AND ANTIMONY(III) TRIS(FLUOROSULFATE) [SB(SO3F)(3)](X)}, journal = {Inorganic Chemistry}, volume = {34}, number = {12}, year = {1995}, note = {ISI Document Delivery No.: RC424Times Cited: 7Cited Reference Count: 52}, month = {Jun}, pages = {3153-3164}, type = {Article}, abstract = {{Following unsuccessful attempts to confirm the existence of previously reported antimony(I) fluorosulfate, Sb(SO3F), the reaction of antimony and fluorosulfuric acid is reinvestigated and synthetic routes are developed that allow the preparation of polymeric [SbF2(SO3F)](x), [SbF(SO3F)(2)](x), and [Sb(SO3F)(3)](x). Recrystallization from fluorosulfuric acid is found to produce single crystals of all three materials, which are suitable for molecular structure determinations by single-crystal X-ray diffraction. Crystals of [SbF2(SO3F)](x) are orthorhombic}, keywords = {CRYSTAL-STRUCTURE, DERIVATIVES, MOSSBAUER, SPECTRA}, isbn = {0020-1669}, url = {://A1995RC42400005}, author = {Zhang, D. L. and Rettig, S. J. and Trotter, J. and Aubke, F.} } @article {3581, title = {ANTIMONY(III) FLUORIDE FLUOROSULFATES - SYNTHESES AND MOLECULAR-STRUCTURES OF ANTIMONY(III) DIFLUORIDE FLUOROSULFATE [SBF2(SO3F)](X), ANTIMONY(III) FLUORIDE BIS(FLUOROSULFATE) [SBF(SO3F)(2)](X), AND ANTIMONY(III) TRIS(FLUOROSULFATE) [SB(SO3F)(3)](X)}, journal = {Inorganic Chemistry}, volume = {34}, number = {12}, year = {1995}, note = {ISI Document Delivery No.: RC424Times Cited: 7Cited Reference Count: 52}, month = {Jun}, pages = {3153-3164}, type = {Article}, abstract = {{Following unsuccessful attempts to confirm the existence of previously reported antimony(I) fluorosulfate, Sb(SO3F), the reaction of antimony and fluorosulfuric acid is reinvestigated and synthetic routes are developed that allow the preparation of polymeric [SbF2(SO3F)](x), [SbF(SO3F)(2)](x), and [Sb(SO3F)(3)](x). Recrystallization from fluorosulfuric acid is found to produce single crystals of all three materials, which are suitable for molecular structure determinations by single-crystal X-ray diffraction. Crystals of [SbF2(SO3F)](x) are orthorhombic}, keywords = {CRYSTAL-STRUCTURE, DERIVATIVES, MOSSBAUER, SPECTRA}, isbn = {0020-1669}, url = {://A1995RC42400005}, author = {Zhang, D. L. and Rettig, S. J. and Trotter, J. and Aubke, F.} } @article {3510, title = {ARTIFICIAL NEURAL-NETWORK AND CLASSICAL LEAST-SQUARES METHODS FOR NEUROTRANSMITTER MIXTURE ANALYSIS}, journal = {Journal of Neuroscience Methods}, volume = {56}, number = {2}, year = {1995}, note = {ISI Document Delivery No.: QH949Times Cited: 5Cited Reference Count: 28}, month = {Feb}, pages = {155-167}, type = {Article}, abstract = {Identification of individual components in biological mixtures can be a difficult problem regardless of the analytical method employed. In this work, Raman spectroscopy was chosen as a prototype analytical method due to its inherent versatility and applicability to aqueous media, making it useful for the study of biological samples. Artificial neural networks (ANNs) and the classical least-squares (CLS) method were used to identify and quantify the Raman spectra of the small-molecule neurotransmitters and mixtures of such molecules. The transfer functions used by a network, as well as the architecture of a network, played an important role in the ability of the network to identify the Raman spectra of individual neurotransmitters and the Raman spectra of neurotransmitter mixtures. Specifically, networks using sigmoid and hyperbolic tangent transfer functions generalized better from the mixtures in the training data set to those in the testing data sets than networks using sine functions. Networks with connections that permit the local processing of inputs generally performed better than other networks on all the testing data sets, and better than the CLS method of curve fitting, on novel spectra of some neurotransmitters. The CLS method was found to perform well on noisy, shifted, and difference spectra.}, keywords = {ARTIFICIAL NEURAL, BACTERIA, CLASSICAL LEAST-SQUARES ANALYSIS, INVIVO VOLTAMMETRY, MIXTURE ANALYSIS, NETWORK, Raman spectroscopy, REGRESSION, SMALL-MOLECULE NEUROTRANSMITTER, SPECTRA, SYSTEM, UV RESONANCE RAMAN}, isbn = {0165-0270}, url = {://A1995QH94900006}, author = {Schulze, H. G. and Greek, L. S. and Gorzalka, B. B. and Bree, A. V. and Blades, M. W. and Turner, R. F. B.} } @article {3510, title = {ARTIFICIAL NEURAL-NETWORK AND CLASSICAL LEAST-SQUARES METHODS FOR NEUROTRANSMITTER MIXTURE ANALYSIS}, journal = {Journal of Neuroscience Methods}, volume = {56}, number = {2}, year = {1995}, note = {ISI Document Delivery No.: QH949Times Cited: 5Cited Reference Count: 28}, month = {Feb}, pages = {155-167}, type = {Article}, abstract = {Identification of individual components in biological mixtures can be a difficult problem regardless of the analytical method employed. In this work, Raman spectroscopy was chosen as a prototype analytical method due to its inherent versatility and applicability to aqueous media, making it useful for the study of biological samples. Artificial neural networks (ANNs) and the classical least-squares (CLS) method were used to identify and quantify the Raman spectra of the small-molecule neurotransmitters and mixtures of such molecules. The transfer functions used by a network, as well as the architecture of a network, played an important role in the ability of the network to identify the Raman spectra of individual neurotransmitters and the Raman spectra of neurotransmitter mixtures. Specifically, networks using sigmoid and hyperbolic tangent transfer functions generalized better from the mixtures in the training data set to those in the testing data sets than networks using sine functions. Networks with connections that permit the local processing of inputs generally performed better than other networks on all the testing data sets, and better than the CLS method of curve fitting, on novel spectra of some neurotransmitters. The CLS method was found to perform well on noisy, shifted, and difference spectra.}, keywords = {ARTIFICIAL NEURAL, BACTERIA, CLASSICAL LEAST-SQUARES ANALYSIS, INVIVO VOLTAMMETRY, MIXTURE ANALYSIS, NETWORK, Raman spectroscopy, REGRESSION, SMALL-MOLECULE NEUROTRANSMITTER, SPECTRA, SYSTEM, UV RESONANCE RAMAN}, isbn = {0165-0270}, url = {://A1995QH94900006}, author = {Schulze, H. G. and Greek, L. S. and Gorzalka, B. B. and Bree, A. V. and Blades, M. W. and Turner, R. F. B.} } @article {3474, title = {ELECTRIC-DIPOLE MOMENT DERIVATIVES FOR GERMANE COMPUTED BY DENSITY-FUNCTIONAL METHOD}, journal = {Indian Journal of Chemistry Section a-Inorganic Bio-Inorganic Physical Theoretical \& Analytical Chemistry}, volume = {34}, number = {10}, year = {1995}, note = {ISI Document Delivery No.: RW566Times Cited: 0Cited Reference Count: 26}, month = {Oct}, pages = {760-764}, type = {Article}, abstract = {The first derivatives of the electric dipole moments along the symmetry coordinates have been computed for D3GeH and DGeH3 by means of the deMon density functional program [St-Amant A \& Salahub D R, Chem phys Lett, 169 (1990) 387] and transformed into those for GeH4, GeD4, and H2GeD2 using relations between the symmetry coordinates for T-d C-3 nu and C-2 nu molecules. Dipole moment derivatives along the normal coordinates of vibration have been calculated using the force field for GeH4 and compared with the available experimental data.}, keywords = {METHANE, SPECTRA}, isbn = {0376-4710}, url = {://A1995RW56600002}, author = {Papousek, D. and Papouskova, D. and Chong, D. P.} } @article {3497, title = {FREQUENCY-SELECTIVE EXCITATION IN MULTIPLE-QUANTUM NMR}, journal = {Journal of Magnetic Resonance Series A}, volume = {112}, number = {1}, year = {1995}, note = {ISI Document Delivery No.: QD079Times Cited: 18Cited Reference Count: 20}, month = {Jan}, pages = {1-6}, type = {Article}, abstract = {Orientation of molecules in liquid-crystalline solvents is a powerful tool for the study of molecular structure and orientation. However, the NMR spectra arising from even relatively small molecules oriented in such solvents can be so complex as to defy analysis. There is demonstrated here a frequency-selective modification of the basic multiple-quantum NMR experiment which is capable of measuring otherwise difficult-to-obtain information in favorable spin systems. (C) 1995 Academic Press, Inc.}, keywords = {AUTOMATED-ANALYSIS, FORMALISM, MOLECULAR-STRUCTURE, nematic, PHASE, PULSE EXPERIMENTS, SOLVENTS, SPECTRA, SPECTROSCOPY}, isbn = {1064-1858}, url = {://A1995QD07900001}, author = {Rendell, J. C. T. and Burnell, E. E.} } @article {3513, title = {MU-SR STUDIES OF FREE-RADICALS IN THE GAS-PHASE}, journal = {Journal of Radioanalytical and Nuclear Chemistry-Articles}, volume = {190}, number = {2}, year = {1995}, note = {ISI Document Delivery No.: QU844Times Cited: 3Cited Reference Count: 22Eotvos Workshops in Science - Nuclear Techniques in Structural ChemistryAUG 31-SEP 04, 1994BUDAPEST, HUNGARYEOTVOS LORAND UNIV, DEPT NUCL CHEM, HUNGARIAN CHEM SOC, ERTHOLD GMBH, HUNGARIAN ACAD SCI, HUNGARIAN US SCI \& TECHNOL JOINT FUND, INT SCI FDN, MINIST CULTURE \& PUBLIC EDUC, HUNGARY, NATL COMM TECHNOL DEV, HUNGARY, PHARE ACCORD}, month = {Mar}, pages = {493-503}, type = {Proceedings Paper}, abstract = {Muonium (Mu=mu(+)+e(-)) is the bound state of a positive muon and an electron. Since the positive muon has a mass about 1/9 of the proton, Mu can be regarded as an ultra light isotope of hydrogen with unusually large mass ratios (Mu:H:D:T=1/9:1:2:3). The muon spin rotation technique (mu SR) relies on the facts that (1) the muon produced in pion decay, pi(+) {\textendash}> mu(+) nu(mu), is 100\% spin polarized and (2) the positron from muon decay is emitted preferentially along the instantaneous muon spin direction at the time of the muon decay. In transverse field mu SR (TF-mu SR), the precession of the muon spin in muonium substituted radicals is directly observed by detecting decay positrons time differentially. From observed radical frequencies, the hyperfine coupling constants (A(mu)) of C(2)H(4)Mu, C(2)D(4)Mu, (13)C(2)H(4)Mu, C(2)F(4)Mu, and C(2)H(3)FMu are determined. In the longitudinal field avoided level crossing (LF-ALC) technique, one observes the resonant loss of the muon spin polarization caused by the crossing of hyperfine levels at particular magnetic fields. The LF-ALC method together with the information on A(mu) obtained from TF-mu SR allows one to determine the magnitude and sign of the nuclear hyperfine constants at alpha- and beta-positions. Results are compared with hydrogen substituted ethyl-radicals and isotope effects are discussed.}, keywords = {CHARGE-EXCHANGE, DYNAMICS, LEVEL-CROSSING RESONANCE, muonium, SPECTRA}, isbn = {0236-5731}, url = {://A1995QU84400038}, author = {Senba, M. and Arseneau, D. J. and Pan, J. J. and Shelley, M. and Fleming, Donald G.} } @article {3425, title = {XPS INVESTIGATIONS OF THE INTERACTIONS OF HYDROGEN WITH THIN-FILMS OF ZIRCONIUM-OXIDE .2. EFFECTS OF HEATING A 26-ANGSTROM THICK-FILM AFTER TREATMENT WITH A HYDROGEN PLASMA}, journal = {Applied Surface Science}, volume = {89}, number = {3}, year = {1995}, note = {ISI Document Delivery No.: RG147Times Cited: 32Cited Reference Count: 19}, month = {Jul}, pages = {263-269}, type = {Article}, abstract = {In order to help establish the role hydrogen plays in the oxidation and reduction of zirconium oxide thin films, XPS was used to study the effects of heating a 26 Angstrom thick ZrO2 film after a hydrogen-plasma treatment. The latter treatment produced a uniform hydrogen-trapped ZrO2 film. Heating to 425 degrees C yielded a reduced suboxide, ZrOx, particularly in the deeper regions of the film, but near the surface this heating produced a zirconium state with Zr3d(5/2) binding energy at 183.4 eV, which is higher than that of ZrO2 by about 0.5 eV. This new chemical state of zirconium appears especially related to Zr-OH bonding. This result, with the observed inhomogeneity of the film, strongly suggests that either H2O or OH- species migrate to the surface region of the hydrogen-trapped ZrO2 film during the heating process.}, keywords = {AES, EELS, SPECTRA, ZRO2}, isbn = {0169-4332}, url = {://A1995RG14700006}, author = {Li, Y. S. and Wong, P. C. and Mitchell, K. A. R.} } @article {3020, title = {ASSESSMENT OF KOHN-SHAM DENSITY-FUNCTIONAL ORBITALS AS APPROXIMATE DYSON ORBITALS FOR THE CALCULATION OF ELECTRON-MOMENTUM-SPECTROSCOPY SCATTERING CROSS-SECTIONS}, journal = {Physical Review A}, volume = {50}, number = {6}, year = {1994}, note = {ISI Document Delivery No.: PX179Times Cited: 122Cited Reference Count: 122Part A}, month = {Dec}, pages = {4707-4728}, type = {Review}, keywords = {BAND-GAPS, BINDING-ENERGY, DIPOLE-MOMENT, ENERGIES, EXCHANGE-CORRELATION POTENTIALS, HARTREE-FOCK LIMIT, IONIZATION-POTENTIALS, LOCAL-DENSITY, OUTER-VALENCE IONIZATION, QUASIPARTICLE, SPECTRA, VERTICAL, WAVE-FUNCTIONS}, isbn = {1050-2947}, url = {://A1994PX17900032}, author = {Duffy, P. and Chong, D. P. and Casida, M. E. and Salahub, D. R.} } @article {3083, title = {ELECTRON DEGRADATION AND THERMALIZATION IN SIH4 GAS}, journal = {Chemical Physics}, volume = {185}, number = {1}, year = {1994}, note = {ISI Document Delivery No.: NV740Times Cited: 9Cited Reference Count: 30}, month = {Jul}, pages = {1-11}, type = {Article}, abstract = {The time-dependent Boltzmann equation is applied to the study of the degradation and thermalization of a nonequilibrium distribution of subexcitation electrons in SiH4. For the small electron to SiH4 mass ratio, the collision operators in the Boltzmann equation reduce to the differential Fokker-Planck operator for elastic collisions and the difference operator for inelastic collisions. A finite difference method of solution of the Boltzmann equation is used. The time evolution of the electron energy distribution and the thermalization time of subexcitation electrons are calculated for initial electron energies of 1, 3 and 5 eV. It is shown that super elastic collisions due to vibrational de-excitation play an important role in the thermalization process.}, keywords = {CROSS-SECTIONS, ENERGY, HELIUM, INITIAL PRODUCTS, NITROGEN, SPECTRA, SUBEXCITATION ELECTRONS, TIME-DEPENDENT ASPECTS, YIELDS}, isbn = {0301-0104}, url = {://A1994NV74000001}, author = {Kowari, K. and Shizgal, B. D.} } @article {3177, title = {EQUATION-OF-MOTION FOR 2 COUPLED SPIN-1 NUCLEI UNDER A COHERENT AND RANDOM HAMILTONIAN}, journal = {Physical Review B}, volume = {50}, number = {13}, year = {1994}, note = {ISI Document Delivery No.: PL412Times Cited: 8Cited Reference Count: 27}, month = {Oct}, pages = {9245-9257}, type = {Article}, abstract = {The time dependence of the density operator for two coupled spin-1 nuclei, such as dideuterium D2 and dinitrogen N-14(2), under the second rank intramolecular dipolar and the first rank spin-rotation Hamiltonians has been derived. It is shown that the relaxation rates for the ortho and para species are not identical. We report the five independent rates for the para and the 21 independent rates for the ortho species. Due to cross relaxation between spin orders which precess at a common frequency, the relaxation for the ortho configuration is not always single exponential. There are 15 cross-relaxation terms between certain spin orders for the ortho species in the slow-motion regime. The complexity of our coupled spin system is discussed for the solid and the Jeener-Broekaert echo sequences. The Zeeman spin-lattice relaxation rates R10 for ortho- and para-dideuterium have been measured experimentally in partially oriented nematic solvents at 304 K using H-2 NMR. The solvents used are PCH-7, 1132, and a 55 wt\% 1132/EBBA mixture. These oriented solvents make it possible to separate the resonances of the ortho and para configurations thereby facilitating the R10 determination directly without multiexponential analysis. The R10 of para-dideuterium is about twice that of ortho-dideuterium in all experiments. Using our calculated expressions for R10 based on quadrupolar, dipolar, and spin-rotation interactions, and performing the proper averaging over the rotational states, we obtain excellent agreement with our experimental results. Good agreement has been obtained with published low-temperature studies as well.}, keywords = {D2, HD, LIQUID, MAGNETIC-RESONANCE, MOLECULES, relaxation, SOLVENTS, SPECTRA}, isbn = {0163-1829}, url = {://A1994PL41200032}, author = {ter Beek, L. C. and Burnell, E. E.} } @article {3155, title = {A MULTIPLE-QUANTUM H-1-NMR STUDY OF PARTIALLY ORIENTED BIPHENYLENE}, journal = {Journal of Magnetic Resonance Series A}, volume = {106}, number = {2}, year = {1994}, note = {ISI Document Delivery No.: MX197Times Cited: 23Cited Reference Count: 23}, month = {Feb}, pages = {223-228}, type = {Article}, keywords = {MOLECULES, SOLVENTS, SPECTRA, SPECTROSCOPY}, isbn = {1064-1858}, url = {://A1994MX19700011}, author = {Polson, J. M. and Burnell, E. E.} } @article {3018, title = {SECONDARY STRUCTURE OF THE ETS DOMAIN PLACES MURINE ETS-1 IN THE SUPERFAMILY OF WINGED HELIX-TURN-HELIX DNA-BINDING PROTEINS}, journal = {Biochemistry}, volume = {33}, number = {46}, year = {1994}, note = {ISI Document Delivery No.: PT485Times Cited: 59Cited Reference Count: 46}, month = {Nov}, pages = {13509-13516}, type = {Article}, abstract = {The members of the ets gene family of transcription factors are characterized by a conserved 85-residue DNA-binding region, termed the ETS domain, that lacks sequence homology to structurally characterized DNA-binding motifs. The secondary structure of the ETS domain of murine Ets-1 was determined on the basis of NMR chemical shifts, NOE and J-coupling constraints, amide hydrogen exchange, circular dichroism, and FT-IR spectroscopy. The ETS domain is composed of three a-helices (H) and four beta-strands (S) arranged in the order H1-S1-S2-H2-H3-S3-S4. The four-stranded antiparallel beta-sheet is the scaffold for a putative helix-turn-helix DNA recognition motif formed by helices 2 and 3. The 25 residues extending beyond the ETS domain to the native C-terminus of the truncated Ets-1 also contain a helical segment. On the basis of the similarity of this topology with that of catabolite activator protein (CAP), heat shock factor (HSF), and hepatocyte nuclear factor (HNF-3 gamma), we propose that ets proteins are members of the superfamily of winged helix-turn-helix DNA-binding proteins.}, keywords = {3-DIMENSIONAL NMR-SPECTROSCOPY, ASSIGNMENT, BACKBONE AMIDE, COUPLING-CONSTANTS, CRYSTAL-STRUCTURE, LARGER, MOTIF, PROTEINS, SIDE-CHAIN RESONANCES, SPECTRA, TRANSCRIPTION FACTORS}, isbn = {0006-2960}, url = {://A1994PT48500001}, author = {Donaldson, L. W. and Petersen, J. M. and Graves, B. J. and McIntosh, L. P.} } @article {2822, title = {MICROWAVE-SPECTRA OF METAL CHLORIDES PRODUCED USING LASER-ABLATION}, journal = {Journal of Chemical Physics}, volume = {99}, number = {5}, year = {1993}, note = {ISI Document Delivery No.: LU722Times Cited: 43Cited Reference Count: 29}, month = {Sep}, pages = {3320-3328}, type = {Article}, abstract = {An apparatus has been constructed to produce metal compounds using laser ablation and to investigate their rotational spectra with a microwave Fourier. transform (MWFT) cavity spectrometer. The first three such compounds that have been studied are silver chloride, aluminum (1) chloride, and copper (I) chloride, produced by ablation of silver, aluminum, and copper rods in the presence of chlorine gas, using a Q-switched Nd:YAG laser (532 nm). The high resolution and sensitivity available with the MWFT cavity spectrometer have permitted the first determination of nuclear spin-rotation coupling constants for AlCl and CuCl. These constants have been used to examine the electronic structures of the molecules. Values of the rotational and nuclear quadrupole coupling constants have also been improved for the three metal chlorides.}, keywords = {ALCL, CUCL, ELECTRIC-DIPOLE MOMENTS, FOURIER-TRANSFORM SPECTROMETER, ROTATIONAL, SPECTRA, STATES}, isbn = {0021-9606}, url = {://A1993LU72200020}, author = {Hensel, K. D. and Styger, C. and Jager, W. and Merer, A. J. and Gerry, M. C. L.} } @article {2807, title = {SOLID-STATE DOUBLE-RESONANCE NMR EXPERIMENTS INVOLVING QUADRUPOLAR AND SPIN 1/2 NUCLEI}, journal = {Journal of Physical Chemistry}, volume = {97}, number = {51}, year = {1993}, note = {ISI Document Delivery No.: MP905Times Cited: 101Cited Reference Count: 58}, month = {Dec}, pages = {13484-13495}, type = {Article}, abstract = {In this work we describe coherence-transfer and dipolar-dephasing double-resonance NMR experiments that demonstrate spatial proximity of quadrupolar and spin 1/2 nuclei (other than protons) in solids. These experiments exploit heteronuclear dipolar couplings, whose magnitudes are proportional to the inverse third power of the internuclear distance and are therefore extremely sensitive to the separation of the coupled spins. Coherence transfer through cross-polarization is observed in both directions between Al-27 (I = 5/2) and P-31 (I = 1/2) nuclei in the inorganic aluminophosphate framework systems VPI-5 and AlPO4-8, and an experimental investigation of the parameters controlling the efficiency of the transfer is presented. Dipolar-dephasing difference experiments, rotational-echo double-resonance (REDOR), and transferred-echo double-resonance (TEDOR) experiments under magic-angle spinning conditions are also demonstrated. Two-dimensional extensions of the cross-polarization and TEDOR experiments reveal the dipolar couplings between specific pairs of Al-27 and P-31 nuclei in two-dimensional correlation spectra, directly mapping connectivities from distinct sites with resolved NMR resonances.}, keywords = {CROSS-POLARIZATION NMR, DOUBLE-ROTOR, MAGIC ANGLE, MAGNETIC-RESONANCE, MAS-NMR, MOLECULAR-SIEVE VPI-5, RESOLUTION, ROTATING SOLIDS, SPECTRA, SPECTROSCOPY}, isbn = {0022-3654}, url = {://A1993MP90500012}, author = {Fyfe, C. A. and Mueller, K. T. and Grondey, H. and Wongmoon, K. C.} } @article {2887, title = {SYNTHESIS AND STRUCTURAL AND MAGNETIC STUDIES OF DIAZINE-BRIDGED COMPLEXES OF COPPER(II) CYANATE - CRYSTAL-STRUCTURE OF POLY[BIS(CYANATO-N)BIS(MU-METHYLPYRAZINE)COPPER(II)]}, journal = {Inorganic Chemistry}, volume = {32}, number = {20}, year = {1993}, note = {ISI Document Delivery No.: LZ815Times Cited: 48Cited Reference Count: 44}, month = {Sep}, pages = {4384-4390}, type = {Article}, abstract = {{Copper(II) cyanate complexes of composition CuLn(NCO)2, Where n is 1 for L = pyrazine (pyz), methylpyrazine (mepyz), and pyridazine (pdz) and n is 2 for L = mepyz and pyridine (py), have been prepared and characterized by vibrational, electronic, and electron spin resonance spectroscopy, differential scanning calorimetry, and magnetic susceptibility studies to cryogenic temperatures. A single-crystal X-ray diffraction study on Cu(mepyz)2(NCO)2 (C12H12CuN6O2), the first compound containing methylpyrazine to be characterized in this way, revealed a two-dimensional square lattice polymeric structure. Its crystals are monoclinic, P2(1)/c, with a = 10.480(2) angstrom}, keywords = {EXCHANGE, IONS, polymer, Pyrazine, PYRIDINE, SPECTRA, SUPEREXCHANGE}, isbn = {0020-1669}, url = {://A1993LZ81500037}, author = {Otieno, T. and Rettig, S. J. and Thompson, R. C. and Trotter, J.} } @article {2887, title = {SYNTHESIS AND STRUCTURAL AND MAGNETIC STUDIES OF DIAZINE-BRIDGED COMPLEXES OF COPPER(II) CYANATE - CRYSTAL-STRUCTURE OF POLY[BIS(CYANATO-N)BIS(MU-METHYLPYRAZINE)COPPER(II)]}, journal = {Inorganic Chemistry}, volume = {32}, number = {20}, year = {1993}, note = {ISI Document Delivery No.: LZ815Times Cited: 48Cited Reference Count: 44}, month = {Sep}, pages = {4384-4390}, type = {Article}, abstract = {{Copper(II) cyanate complexes of composition CuLn(NCO)2, Where n is 1 for L = pyrazine (pyz), methylpyrazine (mepyz), and pyridazine (pdz) and n is 2 for L = mepyz and pyridine (py), have been prepared and characterized by vibrational, electronic, and electron spin resonance spectroscopy, differential scanning calorimetry, and magnetic susceptibility studies to cryogenic temperatures. A single-crystal X-ray diffraction study on Cu(mepyz)2(NCO)2 (C12H12CuN6O2), the first compound containing methylpyrazine to be characterized in this way, revealed a two-dimensional square lattice polymeric structure. Its crystals are monoclinic, P2(1)/c, with a = 10.480(2) angstrom}, keywords = {EXCHANGE, IONS, polymer, Pyrazine, PYRIDINE, SPECTRA, SUPEREXCHANGE}, isbn = {0020-1669}, url = {://A1993LZ81500037}, author = {Otieno, T. and Rettig, S. J. and Thompson, R. C. and Trotter, J.} } @article {2809, title = {X-RAY-ABSORPTION NEAR-EDGE STRUCTURE AT THE FLUORINE-K EDGE IN CAF2 AND BAF2}, journal = {Physical Review B}, volume = {48}, number = {21}, year = {1993}, note = {ISI Document Delivery No.: ML281Times Cited: 9Cited Reference Count: 17}, month = {Dec}, pages = {15578-15583}, type = {Article}, abstract = {A band-structure method has been developed for modeling the near-edge structure in fluorine K-edge x-ray absorption in CaF2 and BaF2. The core-hole potential is included with a supercell technique. The model describes the main features of the experimental absorption spectra up to about 15 eV above the absorption threshold. The excitonic peak at the absorption threshold is followed by a series of peaks whose spacing changes in going from CaF2 to BaF2 by an amount consistent with electron diffraction from crystal-lattice planes. The interpretation of the higher-energy part of the absorption spectrum is complicated by possible multielectron excitations.}, keywords = {emission, SPECTRA, XANES}, isbn = {0163-1829}, url = {://A1993ML28100007}, author = {Gao, Y. and Tiedje, T. and Wong, P. C. and Mitchell, K. A. R.} } @article {7240, title = {HIGH-RESOLUTION C-13 AND N-15 NMR INVESTIGATIONS OF THE MECHANISM OF THE CURING REACTIONS OF CYANATE-BASED POLYMER RESINS IN SOLUTION AND THE SOLID-STATE}, journal = {Macromolecules}, volume = {25}, number = {23}, year = {1992}, note = {ISI Document Delivery No.: JX890Times Cited: 43Cited Reference Count: 22}, month = {Nov}, pages = {6289-6301}, type = {Article}, abstract = {The mechanism of the curing reactions of cyanate polymer resins based on Bisphenol A dicyanate has been investigated both in solution and in the solid state by NMR spectroscopic techniques. To increase S/N and to unambiguously characterize the reactions of the cyanate functionalities, C-13- and N-15-enriched cyanate resins and monocyanate model compounds were used, the latter yielding soluble and isolable analogs. In solution, the main reaction is formation of triazine rings as identified by NMR and MS techniques and characterized by single-crystal X-ray diffraction on an isolated crystalline compound from the monocyanate model compound. Side products are formed by the reaction of the cyanate functionalities with trace water present in the solvent but there is no NMR evidence for the formation of dimeric or other intermediate species prior to triazine ring formation. The isolated resins from the solution curing and also those formed directly by heat curing of the neat resin were characterized by high-resolution solid-state NMR. In the former case triazine ring formation and the presence of side products were confirmed by both C-13 and N-15 solid-state NMR and their proportions quantified. In the case of the neat resin, the curing reaction is shown to be almost quantitative. This is rationalized in terms of the very strong intermolecular intercyanate bonding interactions observed in the crystal structure of the Bisphenol A dicyanate monomer obtained from a single-crystal X-ray diffraction experiment.}, keywords = {MAGIC-ANGLE, NUCLEAR MAGNETIC-RESONANCE, SPECTRA}, isbn = {0024-9297}, url = {://A1992JX89000028}, author = {Fyfe, C. A. and Niu, J. and Rettig, S. J. and Burlinson, N. E. and Reidsema, C. M. and Wang, D. W. and Poliks, M.} } @article {7243, title = {THE MOLECULAR AND ELECTRONIC-STRUCTURE OF 1-PYRAZOLYLPHOSPHAZENES}, journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie}, volume = {70}, number = {6}, year = {1992}, note = {ISI Document Delivery No.: JR097Times Cited: 1Cited Reference Count: 62}, month = {Jun}, pages = {1855-1868}, type = {Article}, abstract = {{The nature of the interactions between pyrazolyl and phosphazene rings has been investigated through the study of the structures of bis(1-pyrazolyl)methane, CH2(H2pz)2, 1, bis[1-(3,5-dimethylpyrazolyl)]methane, CH2(Me2pz)2, 2, the pyrazolylphosphazenes N3P3(Me2pz)6, 3, N4P4(H2pz)8, 4, and N4P4(Me2pz)8, 5, and the partially substituted gem-N3P3Ph2(Me2pz)4, 6. Crystal data are as follows: 1, orthorhombic, P2(1)2(1)2(1)}, keywords = {COMPLEXES, CRYSTAL, CYCLOPHOSPHAZENES, CYCLOTRIPHOSPHAZENE, DIFFRACTION, PHOSPHAZENES, PHOSPHONITRILIC DERIVATIVES, PYRAZOLE, SPECTRA, SUBSTITUENTS}, isbn = {0008-4042}, url = {://A1992JR09700038}, author = {Gallicano, K. D. and Paddock, N. L. and Rettig, S. J. and Trotter, J.} } @article {7367, title = {PURE ROTATIONAL TRANSITIONS OF SILVER-CHLORIDE PREPARED IN AN ELECTRIC-DISCHARGE, OBSERVED WITH A CAVITY MICROWAVE FOURIER-TRANSFORM SPECTROMETER}, journal = {Chemical Physics Letters}, volume = {188}, number = {3-4}, year = {1992}, note = {ISI Document Delivery No.: HB670Times Cited: 18Cited Reference Count: 12}, month = {Jan}, pages = {213-216}, type = {Article}, abstract = {Pure rotational transitions of silver chloride generated in an electric discharge have been observed using a cavity microwave Fourier-transform spectrometer. This is the first report of the successful use of this method to generate a metal compound for microwave spectroscopy. The high resolution of the instrument has permitted an improvement of two orders of magnitude in the precision of the Cl-35 nuclear quadrupole coupling constants.}, keywords = {SPECTRA}, isbn = {0009-2614}, url = {://A1992HB67000011}, author = {Styger, C. and Gerry, M. C. L.} } @article {7380, title = {SELECTED REACTIONS OF FLUORINE-FLUOROSULFATE, FOSO2F}, journal = {Journal of Fluorine Chemistry}, volume = {59}, number = {3}, year = {1992}, note = {ISI Document Delivery No.: KF321Times Cited: 8Cited Reference Count: 36}, month = {Dec}, pages = {333-349}, type = {Article}, abstract = {The reactions of fluorine-fluorosulfate, FOSO2F, with SSF2, SeF4, AsF3 and MoF5 have been studied, and its previously reported reactions with SF4, Br2 and I2 re-investigated in order to test its suitability as a synthetic reagent. All substrates reacted exothermically, and sometimes explosively, between 80-298 K. The presence of the byproducts obtained may be rationalized by the thermal decomposition of some of the FOSO2F, which proceeds along two pathways, i.e. FOSO2F {\textendash}> 1/2O2 + SO2F2 and FOSO2F {\textendash}> 1/2F2 + 1/2S2O6F2, during the extremely exothermic reactions via radical intermediates. The fluorine formed gives rise to fully fluorinated products, and the SO3F. radicals, initially formed, either dimerize to give S2O6F2 or decompose to O2 and S2O5F2. Element fluoride-fluorosulfates, when formed at all, were obtained in low yields only when SO2F2 or SO2FCl were used as suitable moderators. The complete vibrational spectra of EF5OSO2F (E = S, Se or Te) have been studied and assigned. The reactions of I2, Br2 and AsF3 with FOSO2F yielded viscous liquids of the approximate, non-stoichiometric composition EFn(SO5F)5-n (E = As or I) and EFn(SO3F)3-n (E = Br), with n = non-integral number. All compounds were characterized by their vibrational and F-19 NMR spectra, and in the case of SeF5OSO2F by Se-77 NMR methods.}, keywords = {DERIVATIVES, GOLD(III) FLUOROSULFATE, halogen, ION, SPECTRA, TRIS(FLUOROSULFATE)}, isbn = {0022-1139}, url = {://A1992KF32100004}, author = {Willner, H. and Mistry, F. and Aubke, F.} } @article {7034, title = {CHARACTERIZATION OF AN ATMOSPHERIC-PRESSURE PARALLEL-PLATE CAPACITIVELY COUPLED RADIOFREQUENCY PLASMA}, journal = {Applied Spectroscopy}, volume = {45}, number = {9}, year = {1991}, note = {ISI Document Delivery No.: GR646Times Cited: 17Cited Reference Count: 37}, month = {Nov}, pages = {1468-1477}, type = {Article}, abstract = {A new design for a radio-frequency, atmospheric-pressure, parallel-plate capacitively coupled plasma (CCP) which uses water-cooled electrodes is described. Four different sizes of quartz tubes were compared with respect to spatial emission features for support gas and analyte species. Torches studied had the following inside dimensions: a 1-mm capillary tube with round cross section, a 2 x 4 mm tube, a 4 x 4 mm tube, and a 6 x 6 mm tube. Relative emission intensities of near-infrared lines for F, Cl, Br, I, C, N, and O atomic and ionic lines excited with the use of the He-CCP are tabulated. The detection limits range from 10 to 78 pg/s.}, keywords = {ARGON, ATOMIC EMISSION SPECTROSCOPY, capacitively coupled plasma, CHLORINE, DETECTOR, EXCITATION, GAS-CHROMATOGRAPHIC, HELIUM PLASMA, MICROWAVE-INDUCED PLASMA, NEAR-INFRARED EMISSION, NONMETAL ATOMIC EMISSION, RED, SPECTRA, SPECTROMETRY}, isbn = {0003-7028}, url = {://A1991GR64600012}, author = {Huang, D. G. and Blades, M. W.} } @article {7147, title = {FLUOROSULFATE DERIVATIVES OF DIVALENT GOLD}, journal = {Journal of Fluorine Chemistry}, volume = {52}, number = {1}, year = {1991}, note = {ISI Document Delivery No.: FL539Times Cited: 8Cited Reference Count: 34}, month = {Apr}, pages = {13-27}, type = {Article}, abstract = {The reduction of gold(III) fluorosulfate, Au(SO3F)3 with either gold powder or carbon monoxide, in fluorosulfuric acid, HSO3F, yields gold(II) fluorosulfate as a yellow-red solid in high yield. Based on magnetic measurements and vibrational spectra, formulation as mixed valency Au(I) Au(III)-(SO3F)4 is suggested. Evidence from ESR measurements for a solvated, paramagnetic Au(II)-species in the supernatant solution is obtained and discussed.}, keywords = {GOLD(III) FLUOROSULFATE, ION, palladium, SILVER(II), SPECTRA}, isbn = {0022-1139}, url = {://A1991FL53900003}, author = {Willner, H. and Mistry, F. and Hwang, G. and Herring, F. G. and Cader, M. S. R. and Aubke, F.} } @article {6841, title = {LASER DESORPTION IONIZATION FOURIER-TRANSFORM ION-CYCLOTRON RESONANCE MASS-SPECTROMETRY OF CARBOHYDRATES .1. BACTERIAL OLIGOSACCHARIDES CONTAINING NEURAMINIC ACID OR PYRUVIC-ACID ACETAL GROUPS}, journal = {Analytica Chimica Acta}, volume = {241}, number = {2}, year = {1990}, note = {ISI Document Delivery No.: EU533Times Cited: 14Cited Reference Count: 342ND INTERNATIONAL SYMP ON APPLIED MASS SPECTROMETRY IN THE HEALTH SCIENCESAPR 17-20, 1990BARCELONA, SPAINASTRA, APPL BIOSYST, BOEHRINGER MANNHEIM, COMISSIO INTERDEPT RECERCA \& INNOVAC TECHNOL, CONSEJO SUPER INVESTIGAC CIEN, CONSELLERIA ENSENYAMENT GENERALITAT CATALUNYA, FINNIGAN MAT, FONDO INVESTIGAC SANITARIA, REAL SOC ESPANOLA QUIMICA, GRP CROMATOG \& TECN AFINES, HEWLETT PACKARD}, month = {Dec}, pages = {187-199}, type = {Proceedings Paper}, abstract = {The positive- and negative-ion laser desorption ionization Fourier transform ion cyclotron resonance mass spectra of two known, underivatized, linear oligosaccharides obtained by enzymatic hydrolysis with bacterial viruses of the corresponding native bacterial capsular polysaccharides were analyzed. The high-resolution spectra, estimated to be from less than 1 nmol of sample, showed prominent pseudo-molecular ions, as well as fragment ions derived from glycosidic bond and ring cleavages. For some of these frequently observed ring fragments, structures are proposed by analogy to known even-electron gas phase fragmentations and even-electron solution chemistry. The structures of the capsular biopolymers were delineated from these fragmentations, confirming that Klebsiella pneumoniae serotype K3 capsular polysaccharide is made up of a pentasaccharide repeating unit, consisting of four hexoses, one hexuronic acid and one pyruvic acid acetal; and confirming that the tetrasaccharide repeating unit of Escherichia coli serotype K9 is composed of two hexoses, one acetamido hexose and one N-acetyl neuraminic acid. The analysis of oligosaccharides containing N-acetylated sugars was complicated by the fact that an amino hexose attached to a -C2H3O2 ring fragment shares the same elemental formula as an acetamido hexose. Nevertheless, other less ambiguous structural ions could be used for sequencing. Furthermore, analysis of the ring fragments also provided some indication of the positions of linkage of certain monosaccharide residues.}, keywords = {BACTERIOPHAGE-BORNE ENZYMES, CAPSULAR, FAB, FAST ATOM BOMBARDMENT, GLYCOSIDES, ION CYCLOTRON RESONANCE, LASER DESORPTION IONIZATION, MS, OLIGOSACCHARIDES, POLYSACCHARIDE, SEQUENCE, SPECTRA}, isbn = {0003-2670}, url = {://A1990EU53300004}, author = {Lam, Z. and Comisarow, M. B. and Dutton, G. G. S. and Parolis, H. and Parolis, L. A. S. and Bjarnason, A. and Weil, D. A.} } @article {6413, title = {Structural information obtained by negative-ion laser desorption ionization Fourier transform ion cyclotron resonance (l.d.i.-F.t-i.c.r.) mass spectrometry on bacterial capsular polysaccharides}, journal = {Carbohydrate Research}, volume = {180}, number = {2}, year = {1988}, note = {ISI Document Delivery No.: V43RVTimes Cited: 5Cited Reference Count: 20Lam, Zamas Dutton, Guy G. S. Comisarow, Melvin B. Weil, David A. Bjarnason, Asgeir}, month = {Sep}, pages = {C1-C7}, type = {Article}, keywords = {DEGRADATION, DIGOXIN, ENZYMES, GLYCOSIDES, OLIGOSACCHARIDES, SPECTRA}, isbn = {0008-6215}, url = {://000202953100001}, author = {Lam, Z. and Dutton, G. G. S. and Comisarow, M. B. and Weil, D. A. and Bjarnason, A.} }