Rotational Excitation by Slow Electrons. II

Gerjuoy, E.; Stein, S.

doi:10.1103/physrev.98.1848

Cited by 73 publications

(8 citation statements)

References 14 publications

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“…Dalgarno and Moffett 9 also used the Born approximation and included quadrupole and polarization terms in the long-range interaction potential. They obtained 183 22i cross sections which, although larger than those of Gerjuoy and Stein, 8 are smaller than the experimental values. Dalgarno and Henry 10 explicitly calculated the short-range terms and long-range quadrupole contributions to the potentials, but they omitted polarization effects.…”

Section: Introductionmentioning

confidence: 75%

“…They used the distorted wave approximation and obtained results similar in magnitude to those given by Gerjuoy and Stein. 8 The distorted wave approximation was also used by Sampson and Mjolsness, n who included the long-range quadrupole and polarization interactions by cutting off the correct asymptotic forms at some value of r specified by variable parameters. They determined the parameters by fitting their elastic cross sections to low-energy momentum-transfer measurements.…”

Section: Introductionmentioning

confidence: 99%

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Polarization and Exchange Effects in Low-Energy Electron-H2Scattering

1969

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The scattering formalism of Arthurs and Dalgarno, as generalized by Ardill and Davison, is used to take account of exchange in the scattering of slow electrons by molecular hydrogen. Adiabatic polarization terms are included in the direct potential. Exchange and polarization effects on elastic and 0-*2 and l-*3 rotational excitation of H 2 by electron impact are found to be important for energies less than 10 eV. In the energy ranges where measurements and theory overlap, good agreement is obtained for total and differential cross sections, as well as for 0-*2 and l-*3 rotational excitation cross sections.

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Section: Introductionmentioning

confidence: 75%

Section: Introductionmentioning

confidence: 99%

Polarization and Exchange Effects in Low-Energy Electron-H2Scattering

1969

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“…For the H 2 molecule, we consider rotational excitations/de-excitations to/from higher levels (J=3-5), thus ensuring a correct calculation of etps for gas temperatures above 77 K. 81 For the rotational excitations from the J=2-3 levels we adopt the same cross section as for the excitation from J=1, with a threshold correction. 46 As usual, 62 it is assumed that the populations of the rotational excited states follow a Boltzmann distribution, in order to account for superelastic collisions from these levels. The kinetics of vibrational states includes the typical excitation/de-excitation mechanisms due to electron impact collisions (e-V transitions) and heavy species collisions, involving either a vibrational-translational (V-T) or a vibrational-vibrational (V-V) energy transfer.…”

Section: Model Descriptionmentioning

confidence: 99%

“…-(13),(20)-(21),(44),(46),(48), and(58), which corresponds to neglect the vibrational excitation of hydrogen molecules, and the various kinetic mechanisms accounting for the production / destruction of both H atoms and H − negative ions. An observation ofFig.…”

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confidence: 99%

Capacitively coupled radio-frequency hydrogen discharges: The role of kinetics

Marques

Jolly

Alves³

2007

Journal of Applied Physics

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This paper presents a systematic characterization of capacitively-coupled radio-frequency hydrogen discharges, produced within a parallel plate cylindrical setup at different rf applied voltages (V rf = 50 − 600 V), frequencies (f = 13.56 − 40.56 MHz), and pressures (p = 0.2 − 1 torr). A twodimensional, time-dependent fluid model for charged particle transport is self-consistently solved coupled to a homogeneous kinetic model for hydrogen, including vibrationally excited molecular species and electronically excited atomic species. Numerical simulations are compared with experimental measurements of various plasma parameters. A good quantitative agreement is found between simulations and experiment for the coupled electrical power and the plasma potential. The model underestimates the values of the electron density, the self-bias potential, and the H(n=1) atom density with respect to measurements, but agrees with experiment when predicting that all these parameters increase with either V rf , f , or p. The dissociation degree is about 10 −3 for the work conditions considered. Simulations adopt a wall-recombination probability for H atoms that was experimentally measured, thus accounting for surface modification with discharge operating conditions. Results show the key role played by the atomic wall-recombination mechanism in plasma description.

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“…The results of swarm methods for determining the ratio WID of electron drift velocity to diffusion coefficient have found application in a number of recent papers in which collision phenomena between low energy electrons and gas molecules have been discussed (Gerjouy and Stein 1955;Huxley 1956Huxley , 1959Shkarofsky, Bachynski, and Johnston 1961;Frost and Phelps 1961). For some of these applications, more especially those dealing with collision phenomena for electrons with mean energy of several electron-volts, the accuracy of existing data is sufficiently good.…”

Section: Introductionmentioning

confidence: 99%

On the Swarm Method for Determining the Ratio of Electron Drift Velocity to Diffusion Coefficient

Crompton¹,

Jory²

1962

Aust. J. Phys.

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SummaryThe use of data from swarm experiments for electron energies approaching those corresponding to thermal equilibrium demands results of greater precision than has hitherto been available. In order to examine the possibility of producing such data, the swarm method for detennining WID has been extensively examined over a range of values of the parameter Elp where the agreement between the results of recent investigations is not good. A number of factors influencing the accuracy of measurements of this type are discussed. The results for hydrogen which are presented are considered to be subject to an error of less than 1 %. I. INTRODUCTIONThe results of swarm methods for determining the ratio WID of electron drift velocity to diffusion coefficient have found application in a number of recent papers in which collision phenomena between low energy electrons and gas molecules have been discussed (Gerjouy and Stein 1955;Huxley 1956Huxley , 1959Shkarofsky, Bachynski, and Johnston 1961;Frost and Phelps 1961). For some of these applications, more especially those dealing with collision phenomena for electrons with mean energy of several electron-volts, the accuracy of existing data is sufficiently good. Not only are the results of a number of investigations substantially in agreement for this energy range but the degree of accuracy to which they have been obtained is adequate for most purposes. On the other hand, for those applications where the difference in energy between the electrons and gas molecules is important, small errors in the determination of WID become significant as this difference approaches zero. Unfortunately it is in this energy range that the measurements become more difficult and the agreement between the results from various laboratories is not good.In this paper an account is given of a systematic investigation of the swarln method for determining WID using an apparatus which enables the dimensions of the diffusion chamber to be quickly and simply varied. A number of possible sources of error has been investigated both theoretically and experimentally, as a result of which it has been possible to determine the experimental procedures which lead to results of maximum accuracy. The results which have been obtained where these procedures were followed show good agreement over a wide range of values of the experimental parameters and it is considered that the values of WID in hydrogen from O'1

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Rotational Excitation by Slow Electrons. II

Cited by 73 publications

References 14 publications

Polarization and Exchange Effects in Low-Energy Electron-H2Scattering

Polarization and Exchange Effects in Low-Energy Electron-H2Scattering

Capacitively coupled radio-frequency hydrogen discharges: The role of kinetics

On the Swarm Method for Determining the Ratio of Electron Drift Velocity to Diffusion Coefficient

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