@article {2432, title = {A new broadly tunable (7.4-10.2 eV) laser based VUV light source and its first application to aerosol mass spectrometry}, journal = {International Journal of Mass Spectrometry}, volume = {279}, number = {2-3}, year = {2009}, note = {ISI Document Delivery No.: 399TJTimes Cited: 10Cited Reference Count: 78Hanna, S. J. Campuzano-Jost, P. Simpson, E. A. Robb, D. B. Burak, I. Blades, M. W. Hepburn, J. W. Bertram, A. K.}, month = {Jan}, pages = {134-146}, type = {Article}, abstract = {A laser based vacuum ultraviolet (VUV) light source using resonance enhanced four wave difference mixing in xenon gas was developed for near threshold ionization of organics in atmospheric aerosol particles. The source delivers high intensity pulses of VUV light (in the range of 10(10) to 10(13) photons/pulse depending on wavelength, 5 ns FWHM) with a continuously tunable wavelength from 122 nm (10.2 eV) to 168 nm (7.4 eV). The setup allows for tight (< 1 mm(2)) and precise focusing (mu rad pointing angle adjustability), attributes required for single particle detection. The generated VUV is separated from the pump wavelengths by a custom monochromator which ensures high spectral purity and minimizes absorptive losses. The performance of the source was characterized using organic molecules in the gas phase and optimal working conditions are reported. In the gas phase measurements, photoionization efficiency (PIE) curves were collected for seven different organic species with ionization energies spanning the full wavelength range of the VUV source. The measured appearance energies are very close to the literature values of the ionization energies for all seven species. The effectiveness of the source for single particle studies was demonstrated by analysis of individual caffeine aerosols vaporized by a pulsed CO2 laser in an ion trap mass spectrometer. Mass spectra from single particles down to 300 nm in diameter were collected. Excellent signal to noise characteristics for these small particles give a caffeine detection limit of 8 x 10(5) molecules which is equivalent to a single 75 nm aerosol, or approximately 1.5\% of a 300 nm particle. The appearance energy of caffeine originating from the aerosol was also measured and found to be 7.91 +/- 0.05 eV, in good agreement with literature values. (C) 2008 Elsevier B.V. All rights reserved.}, keywords = {Aerosol mass spectrometry, analysis, CROSS-SECTIONS, EFFICIENCY, FUEL-RICH FLAMES, GENERATING PARTICLE BEAMS, ION-TRAP, ONLINE, ORGANIC-COMPOUNDS, PARTICULATE MATTER, PHOTOIONIZATION, SINGLE-PHOTON IONIZATION, SURFACE-ANALYSIS, Vacuum ultraviolet light, VACUUM-ULTRAVIOLET PHOTOIONIZATION}, isbn = {1387-3806}, url = {://000262821900012}, author = {Hanna, S. J. and Campuzano-Jost, P. and Simpson, E. A. and Robb, D. B. and Burak, I. and Blades, M. W. and Hepburn, J. W. and Bertram, A. K.} } @article {1356, title = {Collision-induced alignment of H2O+ drifting in helium}, journal = {Journal of Chemical Physics}, volume = {124}, number = {17}, year = {2006}, note = {ISI Document Delivery No.: 039QQTimes Cited: 0Cited Reference Count: 27}, month = {May}, pages = {8}, type = {Article}, abstract = {The collision-induced alignment of H2O+ drifting in helium is studied with a molecular dynamics method that has been extended to treat nonlinear rigid ions. Rotational distribution functions and averaged quantities are presented in terms of the rho formalism [M. Thachuk, Phys. Rev. A 72, 032722 (2005)], and it is shown that this description gives a very good agreement with simulation results. In addition to velocity and angular velocity autocorrelation functions, a velocity-angular velocity cross correlation function is introduced. This cross correlation function provides insight into the dynamical nature of the alignment mechanism. 2006 American Institute of Physics.}, keywords = {CROSS-SECTIONS, CYTOCHROME-C, ELECTROSTATIC FIELDS, IN-VACUO, INTRINSIC SIZE PARAMETERS, ION-MOTION, MOLECULAR-DYNAMICS, MONTE-CARLO-SIMULATION, POTENTIAL-ENERGY SURFACES, ROTATIONAL ALIGNMENT}, isbn = {0021-9606}, url = {://000237321700019}, author = {Chen, X. and Thachuk, M.} } @article {1551, title = {Slowing-down times and stopping powers for similar to 2-MeV mu(+) in low-pressure gases}, journal = {Physical Review A}, volume = {74}, number = {4}, year = {2006}, note = {ISI Document Delivery No.: 101EXTimes Cited: 3Cited Reference Count: 86Senba, Masayoshi Arseneau, Donald J. Pan, James J. Fleming, Donald G.}, month = {Oct}, pages = {17}, type = {Article}, abstract = {The times taken by positive muons (mu(+)) to slow down from initial energies in the range similar to 3 to 1 MeV, to the energy of the last muonium formation, approximate to 10 eV, at the end of cyclic charge exchange, have been measured in the pure gases H-2, N-2, Ar, and in the gas mixtures Ar-He, Ar-Ne, Ar-CF4, H-2-He, and H-2-SF6, by the muon spin rotation (mu SR) technique. At 1 atm pressure, these slowing-down times, tau(SD), in Ar and N-2, vary from similar to 14 ns at the highest initial energies of 2.8 MeV to 6.5 ns at 1.6 MeV, with much longer times, similar to 34 ns, seen at this energy in H-2. Similar variations are seen in the gas mixtures, depending also on the total charge and nature of the mixture and consistent with well-established (Bragg) additivity rules. The times tau(SD) could also be used to determine the stopping powers, dE/dx, of the positive muon in N-2, Ar, and H-2, at kinetic energies near 2 MeV. The results demonstrate that the mu(+) and proton have the same stopping power at the same projectile velocity, as expected from the historic Bethe-Bloch formula, but not previously shown experimentally to our knowledge for the muon in gases at these energies. The energy of the first neutralization collision forming muonium (hydrogen), which initiates a series of charge-exchanging collisions, is also calculated for He, Ne, and Ar. The formalism necessary to describe the stopping power and moderation times, for either muon or proton, in three energy regimes-the Bethe-Bloch, cyclic charge exchange, and thermalization regimes-is developed and discussed in comparison with the experimental measurements reported here, and elsewhere. The slowing-down times through the first two regimes are controlled by the relevant ionization and charge-exchange cross sections, whereas the final thermalization regime is most sensitive to the forwardness of the elastic scattering cross sections. In this regime the slowing-down times (to kT) at nominal pressures are expected to be less than or similar to 100 ns.}, keywords = {ALPHA-PARTICLES, BINARY THEORY, CHARGE-EXCHANGE, COMPETING PROCESSES, CROSS-SECTIONS, ELECTRON-SPIN EXCHANGE, HYDROGEN-ATOMS, MUONIUM-FORMATION, POSITIVE MUONS, RADIATION-CHEMISTRY}, isbn = {1050-2947}, url = {://000241723100090}, author = {Senba, M. and Arseneau, D. J. and Pan, J. J. and Fleming, Donald G.} } @article {1196, title = {Transport and relaxation properties of isotopomeric hydrogen-helium binary mixtures. I. H-2-He mixtures}, journal = {Molecular Physics}, volume = {103}, number = {1}, year = {2005}, note = {ISI Document Delivery No.: 886WNTimes Cited: 5Cited Reference Count: 75}, month = {Jan}, pages = {17-36}, type = {Article}, abstract = {An extensive comparison has been carried out between calculated and measured bulk properties of H-2-helium mixtures. Detailed comparisons are presented for the interaction second virial coefficient, binary diffusion, mixture shear viscosity and thermal conductivity, rotational relaxation, thermal diffusion field-effects, collision broadening of the depolarized Rayleigh light scattering spectrum, and flow birefringence. Scattering calculations have been carried out for the ab initio potential energy surfaces obtained by Tao (1994, J. chem. Phys., 100, 4947) and Schaefer and Kohler (1985, Physica A, 129, 469). The values for the various bulk gas properties calculated from these two potential surfaces are generally found to lie within or near the experimental uncertainties.}, keywords = {2ND VIRIAL-COEFFICIENTS, AB-INITIO CALCULATION, CROSS-SECTIONS, FACTOR, GAS-MIXTURES, HE-H2 INTERACTION, HIGHER APPROXIMATIONS, NOBLE, PAIR CORRELATION-FUNCTIONS, POTENTIAL-ENERGY SURFACE, ROTATIONAL RELAXATION, THERMAL-DIFFUSION}, isbn = {0026-8976}, url = {://000226263800004}, author = {McCourt, F. R. W. and Weir, D. and Clark, G. B. and Thachuk, M.} } @article {860, title = {Muonium formation as a probe of radiation chemistry in sub- and supercritical carbon dioxide}, journal = {Journal of Physical Chemistry A}, volume = {108}, number = {52}, year = {2004}, note = {ISI Document Delivery No.: 882FPTimes Cited: 5Cited Reference Count: 97}, month = {Dec}, pages = {11613-11625}, type = {Article}, abstract = {Muonium (Mu = mu(+)e(-)), which can be considered a light isotope of the H atom, has been observed for the first time in supercritical CO2 (ScCo2). It is Unreactive on a time scale of a few microseconds and over a wide density range from well below to well above the CO2 critical density rho(c) = 0.47 g/cm(3). The fraction of muon polarization in muonium, P-Mu, does not vary significantly at low densities but changes quickly at the highest densities, approaching zero. This density dependence is reflected in a concomitant increase observed in the lost fraction of polarization, P-L, demonstrating that the dynamics of Mu formation and depolarization in ScCO2 is a direct probe of radiolysis effects in the terminal muon radiation track. In marked contrast to previous studies in hydrogen-containing solvents, C2H6 and H2O, over comparable density ranges, the diamagnetic fraction, P-D, was found to be almost independent of density in CO2, attributed to the formation of the stable solvated MuCO(2)(+) molecular ion in this hydrogen-free solvent. The differing density dependences of both the Mu and the diamagnetic fraction in Co-2, in comparison with the rather similar trends seen for both in C2H6 and H2O, supports previous claims of a significant role played by proton (muon) transfer reactions in the competing processes involved in Mu formation in hydrogen-containing solvents. In addition to this being the first report of radiolysis effects accompanying energetic positive muons stopping in ScCO2, it is the only report of end of track effects in this solvent, which has many applications in nuclear waste management and green chemistry. With a mass intermediate between that of the electron, which has provided most radiation-chemistry studies in ScCO2 to date, and the proton (or alpha-particle), implanted muons provide a unique data set, characteristic of higher LET radiation, that may be relevant to radiolysis effects induced in ScCO2 by alpha decay from heavy nuclei, for which there are no comparable studies.}, keywords = {AQUEOUS-SOLUTIONS, CROSS-SECTIONS, EXCESS ELECTRON-TRANSPORT, GAS-PHASE, LIQUID WATER, MAGNETIC-RESONANCE, ORGANIC FREE-RADICALS, PRESSURE-DEPENDENCE, relaxation, SOLVENT ANIONS, SPIN}, isbn = {1089-5639}, url = {://000225924800018}, author = {Ghandi, K. and Bridges, M. D. and Arseneau, D. J. and Fleming, Donald G.} } @article {681, title = {Conformations of gas-phase lysozyme ions produced from two different solution conformations}, journal = {Analytical Chemistry}, volume = {75}, number = {6}, year = {2003}, note = {ISI Document Delivery No.: 657PQTimes Cited: 15Cited Reference Count: 41}, month = {Mar}, pages = {1325-1330}, type = {Article}, abstract = {Near pH 2.0, lysozyme in water is in its native conformation, and in water/methanol (2/8) it adopts a helical denatured conformation (Kamatari et al. Protein Sci. 1998, 7, 681-688). Hydrogen/deuterium (H/D) exchange of lysozyme in solution confirms that it is partially unfolded at pH 2.0 in water/methanol (v/v = 2/8). With electrospray ionization (ESI) mass spectrometry (MS), lysozyme in water produces ions with charges +7 to +12, with the greatest intensity at +10, whereas lysozyme in water/methanol (2/8) produces ions with charges +6 to +12 with the greatest intensity at +7. Thus, lysozyme is an exception to the rule that a protein denatured in solution forms higher charge states than the same protein in its folded native conformations in solution. Because the same charge states are produced from these two solution conformations, a direct comparison of the properties of the gas-phase ions produced from two very different solution conformations is possible. The conformations of lysozyme ions in the gas phase were studied using cross section measurements and gas-phase H/D exchange. Similar cross sections and H/D exchange levels were observed for same-charge states of lysozyme ions formed from the native and helical denatured conformations in solution. Cross sections show that the ions have compact structures. Thus, disulfide-intact gaseous lysozyme ions generated from the denatured state in water/methanol (2/8) refold into compact structures in the gas phase on a time scale of milliseconds or less.}, keywords = {COLLISION, CROSS-SECTIONS, CYTOCHROME-C, EGG-WHITE LYSOZYME, H/D EXCHANGE, HYDROGEN-DEUTERIUM EXCHANGE, HYDROGEN/DEUTERIUM EXCHANGE, IONIZATION MASS-SPECTROMETRY, IONS, OF-FLIGHT SYSTEM, PROTEIN, UNFOLDING DYNAMICS}, isbn = {0003-2700}, url = {://000181675900014}, author = {Mao, D. M. and Babu, K. R. and Chen, Y. L. and Douglas, D. J.} } @article {442, title = {Tandem mass spectrometry of protein-protein complexes: Cytochrome c-cytochrome b(5)}, journal = {Journal of the American Society for Mass Spectrometry}, volume = {13}, number = {1}, year = {2002}, note = {ISI Document Delivery No.: 504QXTimes Cited: 31Cited Reference Count: 53}, month = {Jan}, pages = {59-71}, type = {Article}, abstract = {An improved method to interpret triple quadrupole MS/MS experiments of complexes of large ions is presented and applied to a study of the complex formed by the proteins cytochrome c and cytochrome b(5). Modeling of the activation and dissociation process shows that most of the reaction occurs near the collision cell exit where ions have the highest internal energies. Experiments at different collision cell pressures or with different collision gases (Ne, Ar, Kr) are interpreted with a previously proposed collision model (Chen et al., Rapid Commun. Mass Spectrom. 1998, 12, 1003-1010) to calculate the internal energy added to ions to cause dissociation. Small but systematic differences under different experimental conditions are attributed to different times available for reaction. A method to correct for this is presented. Ne, Ar, and Kr are found to have similar energy transfer efficiencies. Complexes of cytochrome c and cytochrome b5 are detected in ESI mass spectra but with abundances less than expected from the solution equilibrium. Dissociation of the cytochrome c-cytochrome b(5) complexes with charge k gives as the most abundant fragments, cytochrome b(5)(+3) and cytochrome c(+(k+3)). Adding charges to the complex destabilizes it. A series of cytochrome c variants with Lys residues thought to be involved in solution binding replaced by Ala showed no differences in the energy required to induce dissociation of the gas phase complex. The implications for the binding of the gas phase ions are inconclusive. (J Am Soc Mass Spectrom 2002, 13, 59-71) ((C)) 2002 American Society for Mass Spectrometry.}, keywords = {ACTIVATION, BINDING, COLLISION-INDUCED DISSOCIATION, CROSS-SECTIONS, ELECTROSPRAY-IONIZATION, GAS-PHASE, INTERNAL ENERGY, ION-TRAP, NONCOVALENT COMPLEXES, YEAST ISO-1-FERRICYTOCHROME-C}, isbn = {1044-0305}, url = {://000172868300007}, author = {Mauk, M. R. and Mauk, A. G. and Chen, Y. L. and Douglas, D. J.} } @article {409, title = {Velocity distributions of energetic atoms in planetary exospheres from dissociative recombination}, journal = {Journal of Geophysical Research-Planets}, volume = {107}, number = {E7}, year = {2002}, note = {ISI Document Delivery No.: 610UBTimes Cited: 3Cited Reference Count: 47}, month = {Jul}, pages = {9}, type = {Article}, abstract = {[1] A kinetic theory description of translational energetic atoms in the upper planetary atmosphere is presented. A new analytical result for the velocity distribution of the products of reactive collisions is described. Our calculation takes into account different temperatures of the reactants and arbitrary dependence of the cross section on the relative velocity of the colliding particles. The final result is applied to the production of hot oxygen and carbon by dissociative recombination of O-2(+) and CO+, respectively. The nascent distribution of hot atoms generated in this way is compared with the earlier Monte Carlo calculations. We use the Boltzmann equation to study the thermalization of the hot oxygen via collisions with the thermal oxygen population. The results of this calculation demonstrate quasi-steady state velocity distribution of high-energy oxygen atoms near the exobase of Venus for daytime conditions.}, keywords = {Boltzmann equation, CROSS-SECTIONS, dissociative recombination, ESCAPE, gas kinetic, hot atoms, HOT OXYGEN-ATOMS, HYDROGEN, ION STORAGE-RING, MARS, MONTE-CARLO, NITROGEN-ATOMS, theory, UPPER-ATMOSPHERE, VENUS}, isbn = {0148-0227}, url = {://000178978400004}, author = {Kabin, K. and Shizgal, B. D.} } @article {4316, title = {The coupling of electron thermalization and electron attachment in CCl4/Ar and CCl4/Ne mixtures}, journal = {Journal of Chemical Physics}, volume = {108}, number = {4}, year = {1998}, note = {ISI Document Delivery No.: YR488Times Cited: 11Cited Reference Count: 61}, month = {Jan}, pages = {1587-1600}, type = {Article}, abstract = {The relaxation of a nonequilibrium distribution of electrons in a mixture of CCl4 with either Ar or Ne is studied. In this paper, electron-CCl4 and electron-inert gas elastic collisions, vibrationally inelastic collisions between electrons and CCl4, as well as the electron attachment reaction with CCl4, are included in the analysis. The time dependent electron energy distribution function is determined from the Boltzmann equation and the energy relaxation times are determined. The coupling of the thermalization process and the attachment process are discussed in detail. The results from the calculations are analyzed analogous to experimental studies, and the methodology of the experimental reduction of the data is studied. (C) 1998 American Institute of Physics.}, keywords = {ARGON, CONDUCTIVITY, CROSS-SECTIONS, DEGRADATION, development, FIELD DEPENDENCE, MONTE-CARLO SIMULATION, RARE-GAS MODERATORS, SF6, SWARM, TRANSPORT}, isbn = {0021-9606}, url = {://000071500300035}, author = {Kowari, K. and Leung, K. and Shizgal, B. D.} } @article {4408, title = {Relaxation and transport of molecular systems in the gas phase}, journal = {International Reviews in Physical Chemistry}, volume = {17}, number = {2}, year = {1998}, note = {ISI Document Delivery No.: ZQ123Times Cited: 10Cited Reference Count: 108}, month = {Apr-Jun}, pages = {185-225}, type = {Review}, abstract = {Some of the properties of gas phase relaxation and transport are reviewed with an emphasis on those properties that are due entirely to the presence of internal states in real molecular systems. The theoretical formulations of such non-equilibrium effects is based on the quantum Boltzmann equation. The conditions for the validity and the properties of this equation are reviewed. This includes a general discussion of how the combination of free molecule motion and collisions is required for the approach to global equilibrium. It is shown how the free motion is equivalent to a phase randomization of the elements of the density operator that are off-diagonal in energy. Spin relaxation and the magnetic field dependence (Senftleben-Beenakker effects) of the viscosity for a gas of diatomics are used to illustrate these aspects of the approach to equilibrium.}, keywords = {BINARY COLLISION APPROXIMATION, BOLTZMANN-EQUATION, CARTESIAN TENSORS, COEFFICIENTS, CROSS-SECTIONS, ENERGY, IRREDUCIBLE, MODERATELY DENSE GAS, MUON SPIN RELAXATION, QUANTUM KINETIC-THEORY}, isbn = {0144-235X}, url = {://000073824600003}, author = {Snider, R. F.} } @article {3725, title = {On the existence of a steady electron distribution for systems with electron attachment: Ar-CCl4 mixtures}, journal = {Chemical Physics Letters}, volume = {260}, number = {3-4}, year = {1996}, note = {ISI Document Delivery No.: VJ539Times Cited: 1Cited Reference Count: 18}, month = {Sep}, pages = {365-370}, type = {Article}, abstract = {The relaxation of a nonequilibrium distribution of electrons in a mixture of Ar and CCl4 is studied. In a previous paper [J. Phys. B 34 (1991) 2909], Shizgal demonstrated that with the neglect of vibrationally inelastic collisions, a nonequilibrium steady electron distribution does occur even with the loss of electrons. The rate of disappearance of electrons due to attachment is rapid for high concentrations of CCl4. In this Letter, we extend the previous analysis to include inelastic collisions and find that for CCl4 and Ar mixtures there is no steady electron distribution function with increasing molecular gas concentrations.}, keywords = {ARGON, CROSS-SECTIONS, DEGRADATION, GAS, SF6, THERMALIZATION}, isbn = {0009-2614}, url = {://A1996VJ53900008}, author = {Kowari, K. and Shizgal, B.} } @article {3812, title = {Vibrational nonequilibrium in a supersonic expansion with reaction: Application to O-2-O}, journal = {Journal of Chemical Physics}, volume = {104}, number = {10}, year = {1996}, note = {ISI Document Delivery No.: TX780Times Cited: 27Cited Reference Count: 127}, month = {Mar}, pages = {3579-3597}, type = {Review}, abstract = {The hypersonic expansion of O-2 through a nozzle is considered. The steady nonequilibrium vibrational distribution function of O-2, and the nonequilibrium forward reaction rate coefficient for the dissociation of O-2 are calculated theoretically. In the first instance, the vibrational relaxation of O-2 in the absence of reaction is examined in the temperature range 500-2500 K. The master equation for the vibrational populations, coupled to the steady one-dimensional conservation equations is solved numerically. The vibrational population obtained in this way, is compared to the distribution calculated using either a Treanor model or a Boltzmann distribution characterized by a vibrational temperature. The transition probabilities between O-2 vibrational levels employed take into account the vibrational anharmonicity, and the anisotropic intermolecular potential. For the temperature range 2500-5000 K, the vibrational relaxation including dissociation and recombination is studied. The reactive probabilities that are required for this calculation were obtained from the model of Kiefer and Hajduk [Chem. Phys. 38, 329 (1979)]. (C) 1996 American Institute of Physics.}, keywords = {CHEMICAL-KINETICS, CROSS-SECTIONS, DIATOMIC, DISSOCIATION, HF-HF COLLISIONS, OSCILLATOR, POTENTIAL-ENERGY SURFACE, RATE CONSTANTS, SELF-RELAXATION, STATE, TEMPERATURE}, isbn = {0021-9606}, url = {://A1996TX78000021}, author = {Shizgal, B. D. and Lordet, F.} } @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 {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 {7108, title = {A UNIFORM WKB ANALYSIS OF THE COUPLING OF ELECTRON-ATTACHMENT AND THERMALIZATION IN GASES}, journal = {Journal of Physics B-Atomic Molecular and Optical Physics}, volume = {24}, number = {13}, year = {1991}, note = {ISI Document Delivery No.: FX594Times Cited: 11Cited Reference Count: 44}, month = {Jul}, pages = {2909-2923}, type = {Article}, abstract = {The presence of small amounts of strongly electronegative gases such as SF6 and CCl4 can greatly perturb from equilibrium the electron energy distribution function in a variety of electron devices. The effect of the addition of these electron attaching gases on the relaxation behaviour of a non-equilibrium electron distribution is studied with a linear Fokker-Planck equation. The time dependence of the electron mobility as well as other transport properties can be expressed as a sum of exponential terms with each term characterized by an eigenvalue of the Fokker-Planck operator. This eigenvalue problem can be transformed to a Schrodinger equation with a potential function parametrized by the electron-atom cross sections, the electric field strength and the gas temperature. In the present paper, the eigenvalues and eigenfunctions are calculated with a WKB semiclassical approximation and compared with exact results. The application of the WKB approximation provides a useful way to calculate these strongly perturbed distributions. The specific applications in this paper are for the relaxation of electrons in the inert gases in the presence of small amounts of SF6 or CCl4.}, keywords = {CROSS-SECTIONS, DISCHARGES, FOKKER-PLANCK EQUATION, MIXTURES, MODERATORS, RARE, relaxation, SF6, SWARM DEVELOPMENT, TRANSPORT-COEFFICIENTS}, isbn = {0953-4075}, url = {://A1991FX59400007}, author = {Shizgal, B.} }