Total and partial electron collisional ionization cross sections for CH4, C2H6, SiH4, and Si2H6

Chatham, H.; Hils, D.; Robertson, Robert; Gallagher, A. C.

doi:10.1063/1.447848

Cited by 288 publications

(146 citation statements)

References 14 publications

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“…For methane, the additivity rule uses 12 constants for curve A and 24 constants for curve B. The experimental data by Chatham et al 39 ͑not shown in the figure͒ are very close to those by Durić et al…”

Section: Hydrocarbonssupporting

confidence: 74%

New model for electron-impact ionization cross sections of molecules

Hwang¹,

Kim

Rudd³

1996

The Journal of Chemical Physics

530

362

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A theoretical model for electron-impact ionization cross sections, which has been developed primarily for atoms and atomic ions, is applied to neutral molecules. The new model combines the binary-encounter theory and the Bethe theory for electron-impact ionization, and uses minimal theoretical data for the ground state of the target molecule, which are readily available from public-domain molecular structure codes such as GAMESS. The theory is called the binaryencounter Bethe (BEB) model, and does not, in principle, involve any adjustable parameters. Applications to 19 molecules, including H 2 , NO, CH 2 , C 6 H 6 , and SF 6 , are presented, demonstrating that the BEB model provides total ionization cross sections by electron impact from threshold to several keV with an average accuracy of 15% or better at the cross section peak, except for SiF 3 . The BEB model can be applied to stable molecules as well as to transient radicals. History:Received 13 A theoretical model for electron-impact ionization cross sections, which has been developed primarily for atoms and atomic ions, is applied to neutral molecules. The new model combines the binary-encounter theory and the Bethe theory for electron-impact ionization, and uses minimal theoretical data for the ground state of the target molecule, which are readily available from public-domain molecular structure codes such as GAMESS. The theory is called the binary-encounter Bethe ͑BEB͒ model, and does not, in principle, involve any adjustable parameters. Applications to 19 molecules, including H 2 , NO, CH 2 , C 6 H 6 , and SF 6 , are presented, demonstrating that the BEB model provides total ionization cross sections by electron impact from threshold to several keV with an average accuracy of 15% or better at the cross section peak, except for SiF 3 . The BEB model can be applied to stable molecules as well as to transient radicals.

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Section: Hydrocarbonssupporting

confidence: 74%

New model for electron-impact ionization cross sections of molecules

Hwang¹,

Kim

Rudd³

1996

The Journal of Chemical Physics

530

362

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“…4͒ that this is not the case for SiH 4 , whose vertical IP is 12.7 eV, 20 while the adiabatic IP is 11.65 eV. One feature that distinguishes SiH 4 from CH 4 and NH 3 is that few parent ions, SiH 4 ϩ , are generated in the former, 15,17 while the parent ions of the latter are not difficult to produce.…”

Section: Discussionmentioning

confidence: 87%

“…For Si 2 H 6 , the experimental results of Chatham et al 17 and Krishnakumar and Srivastava 18 differ markedly in the peak region ͑Fig. 5͒.…”

Section: B Silane (Sih 4 ) and Disilane (Si 2 H 6 )mentioning

confidence: 91%

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Electron-impact total ionization cross sections of silicon and germanium hydrides

Ali

Kim

Hwang

et al. 1997

The Journal of Chemical Physics

105

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Electron-impact total ionization cross sections of some silicon and germanium compounds have been calculated by applying a new theoretical model that has been found to be reliable for a wide range of molecules. The new theory, the binary-encounter-Bethe (BEB) model, combines the binary-encounter theory and the Bethe theory for electron-impact ionization, and uses simple theoretical molecular orbital data-binding energies, average kinetic energies, and occupation numbers-which are readily available from molecular structure codes. Total ionization cross sections of SiH, SiH 2 , SiH 3 , SiH 4 , Si 2 H 6 , Si(CH 3 ) 4 , GeH, GeH 2 , GeH 3 , GeH 4 , and Ge 2 H 6 are presented for incident electron energies T from threshold to 1 keV, and compared to available experimental data. Theory and experiment agree well for SiH x , x=1-4, from thresholds to T<80 eV, while theoretical peaks occur at lower T than experimental peaks for SiH x , x=1-3. No experimental data are available for germanium hydrides for comparison. The theoretical cross sections are given by a compact analytic form suitable for applications in plasma processing. ©1997 American Institute of Physics. History:Received 27 January 1997; accepted 4 March 1997 Electron-impact total ionization cross sections of some silicon and germanium compounds have been calculated by applying a new theoretical model that has been found to be reliable for a wide range of molecules. The new theory, the binary-encounter-Bethe ͑BEB͒ model, combines the binary-encounter theory and the Bethe theory for electron-impact ionization, and uses simple theoretical molecular orbital data-binding energies, average kinetic energies, and occupation numbers-which are readily available from molecular structure codes. Total ionization cross sections of SiH, SiH 2 , SiH 3 , SiH 4 , Si 2 H 6 , Si͑CH 3 ͒ 4 , GeH, GeH 2 , GeH 3 , GeH 4 , and Ge 2 H 6 are presented for incident electron energies T from threshold to 1 keV, and compared to available experimental data. Theory and experiment agree well for SiH x , xϭ1 -4, from thresholds to T Ͻ80 eV, while theoretical peaks occur at lower T than experimental peaks for SiH x , xϭ1 -3. No experimental data are available for germanium hydrides for comparison. The theoretical cross sections are given by a compact analytic form suitable for applications in plasma processing.

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“…Previous results (Table 1) are several eV higher in energy. By comparing the values given in Table. l it is seen that the above value concurs with the energy of formation of process [7] but is significantly lower than other measured values except for that of Chatham et al (12) which has a large error. This discrepancy is indicative .of -the lack of sensitivity of these previous works.…”

Section: C2hmentioning

confidence: 56%

Electroionization study of ethane: ionization and appearance energies, ion-pair formations and negative ions

Plessis¹,

Marmet²

1987

Can. J. Chem.

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Threshold region ionization efficiency curves of ethane, of all singly charged fragments consisting of at least one carbon atom, and of [Formula: see text] and [Formula: see text] are presented and analysed. An energy filtered monoenergetic electron beam apparatus capable of producing very high signal-to-noise ratio data was used to study these ions. The C2H6 ionization energy is evaluated to be 11.57 ± 0.02 eV and structures due to competition with [Formula: see text] fragment production are observed at higher energy in the [Formula: see text] curve. As a result of the high apparatus sensitivity several of the measured appearance energies are lower (some by several eV) than previously reported. [Formula: see text], [Formula: see text], and [Formula: see text] ion pair formations are observed. The [Formula: see text] ion pair formation, previously reported by several studies, is shown to be obscured by the isotopic [Formula: see text] fragment signal.

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Total and partial electron collisional ionization cross sections for CH4, C2H6, SiH4, and Si2H6

Abstract: The total and partial electron collisional ionization cross sections for CH4, C2H6, SiH4, and Si2H6 have been measured for electron energies from threshold to 300 eV. Comparisons are made to earlier measurements.

Cited by 288 publications

References 14 publications

New model for electron-impact ionization cross sections of molecules

New model for electron-impact ionization cross sections of molecules

Electron-impact total ionization cross sections of silicon and germanium hydrides

Electroionization study of ethane: ionization and appearance energies, ion-pair formations and negative ions

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