@article {2612, title = {Comparison of Dopants for Charge Exchange Ionization of Nonpolar Polycyclic Aromatic Hydrocarbons with Reversed-Phase LC-APPI-MS}, journal = {Journal of the American Society for Mass Spectrometry}, volume = {20}, number = {1}, year = {2009}, note = {ISI Document Delivery No.: 393RRTimes Cited: 4Cited Reference Count: 16Smith, Derek R. Robb, Damon B. Blades, Michael W.}, month = {Jan}, pages = {73-79}, type = {Article}, abstract = {Atmospheric pressure photoionization (APPI) is capable of ionizing nonpolar Compounds in LC/MS, through charge exchange reactions following photoionization of a dopant. Recently, several novel dopants-chlorobenzene, bromobenzene, 2,4-difluoroanisole, and 3-(trifluoromethyl)anisole-have been identified as having properties making them well-suited to serve as dopants for charge exchange ionization under reversed-phase LC conditions. Here, we report the results of experiments comparing their effectiveness to that of established dopants-toluene, anisole, and a toluene/anisole Mixture, for the charge exchange ionization of model nonpolar compounds-the 16 polycyclic aromatic hydrocarbons (PAHs) identified by the US EPA as priority pollutants-when using a conventional reversed-phase LC method. Chloro- and bromobenzene were found to be much more effective than toluene for all the PAHs, due to the relatively low reactivity of their photoions with the solvent. Their overall performance was also better than that of anisole, due to anisole{\textquoteright}s ineffectiveness toward higher-IE compounds. Further, the experiments revealed that anisole{\textquoteright}s performance for higher-IE compounds can be dramatically improved by introducing it as a dilute Solution in toluene, rather than neat. The two fluoroanisoles provided the highest overall sensitivity, by a slim margin, when introduced as dilute solutions in either chloro- or bromobenzene. (J Am Soc Mass Spectrom 2009, 20, 73-79) (C) 2009 Published by Elsevier Inc. on behalf of American Society for Mass Spectrometry}, keywords = {ATMOSPHERIC-PRESSURE PHOTOIONIZATION, ENERGIES, LC/MS, MASS-SPECTROMETRY, PROTON, SOLVENT}, isbn = {1044-0305}, url = {://000262390900011}, author = {Smith, D. R. and Robb, D. B. and Blades, M. W.} } @article {1602, title = {Search for suitable approximation methods for fullerene structure and relative stability studies: Case study with C50}, journal = {J. Chem. Phys.}, volume = {125}, number = {9}, year = {2006}, note = {ISI Document Delivery No.: 081XSTimes Cited: 13Cited Reference Count: 48Tian, Wei Quan Feng, Ji-Kang Wang, Yan Alexander Aoki, Yuriko}, month = {Sep}, pages = {094105}, type = {Article}, abstract = {

Local density approximation (LDA), several popular general gradient approximation (GGA), hybrid module based density functional theoretical methods: SVWN, BLYP, PBE, HCTH, B3LYP, PBE1PBE, B1LYP, and BHandHLYP, and some nonstandard hybrid methods are applied in geometry prediction for C-60 and C-70. HCTH with 3-21G basis set is found to be one of the best methods for fullerene structural prediction. In the predictions of relative stability of C-50 isomers, PM3 is an efficient method in the first step for sorting out the most stable isomers. HCTH with 3-21G predicts very good geometries for C-50, similar to the performance of B3LYP/6-31G(d). The gap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital from the predictions of all the density functional theory methods has the following descending order: E-gap(half-and-half hybrid)\> E-gap(B3LYP)\> E-gap(HCTH)(GGA)\> E-gap(SVWN)(LDA). (c) 2006 American Institute of Physics.

}, keywords = {ADJUSTABLE-PARAMETERS, BUCKMINSTERFULLERENE, C-70, DENSITY-FUNCTIONAL THEORY, ELECTRON-DIFFRACTION, ENERGIES, GENERALIZED GRADIENT APPROXIMATION, MOLECULAR-STRUCTURE, PERFORMANCE, PHASE, SEMIEMPIRICAL METHODS}, isbn = {0021-9606}, url = {://000240351500008}, author = {W. Q. Tian* and J.-K. Feng and Wang, Y. A. and Aoki, Y.} } @article {709, title = {Excess chemical potentials and partial molar enthalpies in aqueous 1,2-and 1,3-propanediols at 25 degrees C}, journal = {Journal of Solution Chemistry}, volume = {32}, number = {2}, year = {2003}, note = {ISI Document Delivery No.: 661CMTimes Cited: 4Cited Reference Count: 24}, month = {Feb}, pages = {137-153}, type = {Article}, abstract = {Excess chemical potentials and excess partial molar enthalpies of 1,2- and 1,3-propanediols ( abbreviated as 12P and 13P), mu(i)(E), and H-i(E) ( i = 12P or 13P) were determined in the respective binary aqueous solutions at 25degreesC. For both systems, the values of mu(i)(E) are almost zero, within +/-0.4 kJ-mol(-1). However, the excess partial molar enthalpies, H-i(E) show a sharp mole fraction dependence in the water-rich region. Thus, the systems are highly nonideal, in spite of almost zero mu(i)(E). Namely, the enthalpy-entropy compensation is almost complete. From the slopes of the HE i against the respective mole fraction x(i) we obtain the enthalpic interaction functions between solutes, H-i-i(E), ( i = 12P or 13P). Using these quantities and comparing them with the equivalent quantities for binary aqueous solutions of 1-propanol ( 1P), 2-propanol (2P), glycerol (Gly), and dimethyl sulfoxide ( DMSO), we conclude that there are three composition regions in each of which mixing schemes are qualitatively different. Mixing Schemes II and III, operative in the intermediate and the solute-rich regions, seem similar in all the binary aqueous solutions mentioned above. Mixing Scheme I in the water-rich region is different from solute to solute. 12P shows a behavior similar to that of DMSO, which is somewhat different from typical hydrophobic solute, 1P or 2P. 13P, on the other hand, is less hydrophobic than 12P, and shows a behavior closer to glycerol, which shows hydrophilic behavior.}, keywords = {2-and 1, 3-propanediols, ALCOHOL, chemical potentials, ENERGIES, ENTHALPIES, ENTROPIES, H2O, interaction functions, MIXING SCHEMES, mixing schemes in aqueous 1, MOLECULAR-ORGANIZATION, NONELECTROLYTES, partial molar, TERT-BUTANOL MIXTURES, VOLUMES, WATER-RICH REGION}, isbn = {0095-9782}, url = {://000181873700003}, author = {Parsons, M. T. and Lau, F. W. and Yee, E. G. M. and Koga,Yoshikata} } @article {419, title = {The E (3)Pi-X (3)Delta transition of jet-cooled TiO observed in absorption}, journal = {Journal of Molecular Spectroscopy}, volume = {212}, number = {2}, year = {2002}, note = {ISI Document Delivery No.: 561KZTimes Cited: 7Cited Reference Count: 43}, month = {Apr}, pages = {133-141}, type = {Article}, abstract = {The (0,0) and (1,0) bands of the E(3)Pi-X (3)Delta transition of TiO in the near-infrared have been recorded by frequency modulated laser absorption spectroscopy in a laser ablation/free jet expansion source. The observed linewidths (FWHM) varied from 300 to 500 MHz according to the expansion conditions and are dominated by residual Doppler broadening in the unskimmed source. Data for the (0,0) band have been obtained for TiO molecules containing all the naturally occurring Ti isotopes but, for the weaker (1,0) band, only for (TiO)-Ti-48. Rotational constants for the two upper state vibrational levels were derived by fitting the data to an effective Hamiltonian; equilibrium parameters have been calculated. The experimental results are compared to the results of ab initio calculations on the E-X system. Ab initio results for the b-a system and for the lowest (3)Sigma(-) state are also presented. They indicate that the D (3)Sigma(-) state is not a very low-lying state. (C) 2002 Elsevier Science (USA).}, keywords = {0, 0 BAND, DOUBLING PARAMETERS, electronic absorption spectroscopy, ELECTRONIC STATES, ENERGIES, FOURIER-TRANSFORM SPECTROSCOPY, laser spectroscopy, MOLECULES, RESOLUTION, ROTATIONAL ANALYSIS, TITANIUM MONOXIDE, titanium oxide, VO}, isbn = {0022-2852}, url = {://000176140900001}, author = {Kobayashi, K. and Hall, G. E. and Muckerman, J. T. and Sears, T. J. and Merer, A. J.} } @article {4831, title = {Computational study of vertical ionization potentials using density functional theory and Green{\textquoteright}s function methods}, journal = {Journal of the Chinese Chemical Society}, volume = {47}, number = {1}, year = {2000}, note = {ISI Document Delivery No.: 295BRTimes Cited: 6Cited Reference Count: 44}, month = {Feb}, pages = {141-147}, type = {Article}, abstract = {Over one hundred vertical ionization potentials (VIPs) were computed using density functional theory (DFT) and Green{\textquoteright}s function (GF) based methods. The DFT approaches include the unrestricted transition state (uTS) and unrestricted diffuse ionization (uDI) approximations using the Becke88-Perdew86 exchange-correlation functional. Green{\textquoteright}s function methods include the outer-valence GF (OVGF) approach, the parametrized GF2 (pGF2), and the parametrized GF2 times screened interaction (pGW2) approximations. DFT computations of IPs using the uTS approximation was found to be nearly as accurate as those predicted using the elaborate OVGF method. The much more computationally efficient uDI approximation provides predictions of moderate accuracy and is recommended for computing IPs for larger molecules. We have observed that the average absolute deviations from a uDI calculation using poorer basis set (DZVP) and poorer geometry (AM1 optimization) is only slightly larger.}, keywords = {ALGORITHM, APPROXIMATION, density functional theory, ENERGIES, Green{\textquoteright}s function, MOLECULES, PHOTOELECTRON-SPECTRA, POTENTIALS, SPECTROSCOPY, vertical ionization}, isbn = {0009-4536}, url = {://000085946500016}, author = {Hu, C. H. and Chong, D. P.} } @article {4756, title = {Excess chemical potentials, partial molar enthalpies and entropies in binary aqueous acetone and tetramethyl urea at 25 degrees C}, journal = {Fluid Phase Equilibria}, volume = {175}, number = {1-2}, year = {2000}, note = {ISI Document Delivery No.: 380MDTimes Cited: 15Cited Reference Count: 12}, month = {Nov}, pages = {35-43}, type = {Article}, abstract = {We measured excess chemical potentials, mu (E)(i), excess partial molar enthalpy, H-i(E), of solute i in aqueous acetone and tetramethyl urea (TMU). We then evaluated excess partial molar entropy, S-i(E). They all were determined accurately and in small increments in mole fraction, and hence, it was possible to take one more derivative with respect to mole fraction. These higher derivatives were used to learn more about intermolecular interaction in solution. Furthermore, they were used to detect anomalous thermodynamic behaviour, in particular a qualitative change in mixing scheme. We conclude that in both aqueous solutions, three distinctively different mixing schemes are operative depending on the composition range, and that in the most H2O-rich region, solute molecules enhance the hydrogen bond network of H2O in their immediate vicinity. However, the hydrogen bond probability in the bulk of H2O away from solute is reduced. (C) 2000 Elsevier Science B.V. All rights reserved.}, keywords = {aqueous acetone, ENERGIES, excess chemical potential, interaction functions, MIXTURES, molar enthalpy and entropy, PARTIAL, TETRAMETHYL UREA, VOLUMES}, isbn = {0378-3812}, url = {://000165704900004}, author = {Chen, D. H. C. and Chu, P. M. and Tanaka, S. H. and To, E. C. H. and Koga,Yoshikata} } @article {4155, title = {Intermolecular interactions of lysozyme and small alcohols: A calorimetric investigation}, journal = {Journal of Physical Chemistry B}, volume = {101}, number = {29}, year = {1997}, note = {ISI Document Delivery No.: XM058Times Cited: 23Cited Reference Count: 34}, month = {Jul}, pages = {5755-5758}, type = {Article}, abstract = {Isothermal titration calorimetry was used to measure transfer enthalpies of hen egg white lysozyme from water to aqueous solutions of methanol, ethanol, 1-propanol, glycerol, and 2,2,2-trifluoroethanol. Excess partial molar enthalpies of lysozyme at infinite dilution in the alcoholic solvents, H-infinity(L)E, were calculated, and the dependence of H-infinity(L)E on the concentration of the alcohol, was utilized to elucidate the enthalpy of alcohol-protein interactions. Results show that, at low alcohol concentrations, alcohol-protein interactions are unfavorable in terms of enthalpy (endothermic), while at higher concentrations they are favorable (exothermic). The change from endothermic to exothermic interactions happened sharply over a narrow alcohol concentration interval, and was found to occur concurrently with denaturation of the protein in some but not all cases. Comparison of the present results with previous investigations of simple binary and ternary aqueous solutions suggests that the change of sign of the interaction enthalpy is related to the water-water hydrogen bonding properties in the alcohol mixtures. It is argued that modifications by the alcohol of the percolated hydrogen bond network govern the enthalpy of alcohol-lysozyme interactions in the most water-rich samples. This suggests that occupancy by the alcohol of a binding site on the surface of the protein may not be necessary for the alcohol to affect the properties of the protein. At higher alcohol concentrations the observed interaction enthalpies are dominated by direct ({\textquoteright}{\textquoteright}intrinsic{\textquoteright}{\textquoteright}) effects of protein-alcohol interactions, which are exothermic.}, keywords = {25-DEGREES-C, ENERGIES, GLOBULAR-PROTEINS, INDUCED REVERSIBLE DENATURATION, MIXTURES, MONOHYDRIC ALCOHOLS, STABILIZATION, THERMODYNAMIC INVESTIGATIONS, TRIFLUOROETHANOL, VAPOR-PRESSURES, WATER}, isbn = {1089-5647}, url = {://A1997XM05800021}, author = {Westh, P. and Koga,Yoshikata} } @article {3999, title = {The parametrized second-order Green function times screened interaction (pGW2) approximation for calculation of outer valence ionization potentials}, journal = {Journal of Electron Spectroscopy and Related Phenomena}, volume = {85}, number = {1-2}, year = {1997}, note = {ISI Document Delivery No.: XK875Times Cited: 6Cited Reference Count: 44}, month = {Apr}, pages = {39-46}, type = {Article}, abstract = {In this paper we introduce a parameter to the second-order Green function times screened-interaction of Hedin{\textquoteright}s (GW2). The valence ionization potentials (IPs) predicted by the parametrized GW2 (pGW2) scheme compare well with experiment for a collection of 45 valence IPs for 13 small molecules. With the cc-pVTZ basis set the average absolute deviation between theoretical prediction and experiment is 0.25 eV. With the smaller cc-pVDZ basis set using the option scaling parameter (0.48) obtained from the cc-pVTZ basis set, the average absolute deviation is 0.32 eV. We have also calculated the 10 valence IPs of glycine at the geometries of its two lowest energy conformers. Our results confirm that comformer I is the global minimum, The predicted valence IPs of glycine I agree excellently with experiment (average absolute deviation 0.20 eV), and lead to are assignment of the photoelectron spectrum. (C) 1997 Elsevier Science B.V.}, keywords = {CONFIGURATION-INTERACTION, ELECTRON CORRELATION, ENERGIES, GLYCINE, Green function method, interaction, ionization potential, MOLECULES, PHOTOELECTRON-SPECTRA, QUASI-PARTICLE, QUASIPARTICLE, screened, SELF-ENERGY, SEMICONDUCTORS, SPECTROSCOPY}, isbn = {0368-2048}, url = {://A1997XK87500006}, author = {Hu, C. H. and Chong, D. P. and Casida, M. E.} } @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 {2995, title = {RELAXATION DYNAMICS OF HOT PROTONS IN A THERMAL BATH OF ATOMIC-HYDROGEN}, journal = {Physical Review E}, volume = {49}, number = {1}, year = {1994}, note = {ISI Document Delivery No.: MV514Times Cited: 10Cited Reference Count: 58}, month = {Jan}, pages = {347-358}, type = {Article}, abstract = {We present a rigorous kinetic theory formulation of the relaxation of hot protons (H+) in a bath of thermal atomic hydrogen (H). We apply the (well-known) quantum-mechanical scattering theory to (H+,H) collisions and calculate the differential elastic cross section as a function of collision energy and scattering angle. This calculation includes the effects Of both direct and charge-exchange scattering. We then solve the time-dependent Boltzmann equation numerically for the H+ distribution function with an initial delta-function distribution. We also consider two approximate models for the collision dynamics, each based on the assumption that charge exchange dominates the relaxation and that no momentum is transferred in a collision (the linear-trajectory approximation). The first model uses the Rapp-Francis [J. Chem. Phys. 37, 2631 (1962)] energy-dependent cross section in the exact kernel which defines the Boltzmann collision operator. The second model uses a hard-sphere cross section in an approximate collision kernel. We compare the relaxation behavior calculated with the approximate formulations with the exact solution. We also calculate the mobility of H+ in H and compare the exact and-approximate; formulations. This study has applications to processes in astrophysics and aeronomy such as the non-thermal escape of H from planetary atmospheres.}, keywords = {CHARGE-EXCHANGE, COLLISION KERNELS, EIGENVALUES, ENERGIES, equation, ESCAPE, EXOSPHERE, TRANSPORT, VENUS}, isbn = {1063-651X}, url = {://A1994MV51400048}, author = {Clarke, A. S. and Shizgal, B.} } @article {2889, title = {MUONIUM ATOM SPIN-EXCHANGE WITH ALKALI-METAL VAPORS - MU+CS}, journal = {Physical Review A}, volume = {48}, number = {2}, year = {1993}, note = {ISI Document Delivery No.: LQ990Times Cited: 15Cited Reference Count: 77}, month = {Aug}, pages = {1218-1226}, type = {Article}, abstract = {The thermally averaged total electron spin-flip cross sections (sigma(SF)) for Mu-Cs have been measured in a 2 atm N2 moderator at 543, 566, and 643 K using the muon-spin-rotation technique. Within an overall experimental error of +/-15\%, the measured cross sections can be taken as temperature independent, sigma(SF)=39.7+/-6.0 X 10(-16) cm2, though there may be a trend to decreased values at the lower temperatures. This average value is considerably lower than either the early calculated results of Dalgarno and Rudge [Proc. R. Soc. London Ser. A 286, 519 (1965)] or the more recent ones of Cole and Olson [Phys. Rev. A 31, 2137 (1985)] for the corresponding H-Cs collisions, indicating a dramatic isotope effect.}, keywords = {ADDITION-REACTIONS, COLLISIONS, CROSS-SECTIONS, ENERGIES, HYDROGEN-ATOMS, LOW-PRESSURE GASES, MU-SR, RATE CONSTANTS, relaxation, SCATTERING}, isbn = {1050-2947}, url = {://A1993LQ99000046}, author = {Pan, J. J. and Senba, M. and Arseneau, D. J. and Kempton, J. R. and Fleming, Donald G. and Baer, S. and Gonzalez, A. C. and Snooks, R.} } @article {6980, title = {QUASI-PARTICLE EQUATION FROM THE CONFIGURATION-INTERACTION (CI) WAVE-FUNCTION METHOD}, journal = {International Journal of Quantum Chemistry}, volume = {40}, number = {2}, year = {1991}, note = {ISI Document Delivery No.: FX545Times Cited: 7Cited Reference Count: 42}, month = {Aug}, pages = {225-242}, type = {Article}, abstract = {The Green-function method is a well-known way to reduce the quantum mechanical problem of n electrons moving in the field of clamped nuclei to the problem of solving a one-electron Schrodinger equation (the quasi-particle equation) involving a pseudopotential (the self-energy). This method is widely used in solid-state, low-energy electron-molecule scattering, ionization, and electron attachment theory, and much work has focused on finding accurate self-energy approximations. Unfortunately, the operator nature of the fundamental quantity (Green function) in the usual quasi-particle equation formalism significantly complicates the derivation of self-energy approximations, in turn significantly complicating applications to inelastic scattering and multiconfigurational bound-state problems. For these problems or wherever the operator approach becomes inconvenient, we propose an alternative quasi-particle equation derived wholely within a configuration interaction wave-function formalism and intended to describe the same phenomenology as does the Green function quasi-particle equation. Our derivation refers specifically to electron removal but is readily generalized to electron attachment and scattering. Although the Green function and wave-function quasi-particle equations are different, we emphasize the parallels by rederiving both equations within the equations-of-motion formalism and then producing a wave-function analog of the Green function two-particle-hole Tamm-Dancoff approximation.}, keywords = {APPROXIMATION, CLOSED-SHELL ATOMS, CORRELATED WAVEFUNCTIONS, ELECTRON PROPAGATOR THEORY, ENERGIES, EXTENSION, IONIZATION-POTENTIALS, KOOPMANS THEOREM, MOLECULES, SCATTERING}, isbn = {0020-7608}, url = {://A1991FX54500005}, author = {Casida, M. E. and Chong, D. P.} }