Ionization Cross Sections of Gas Molecules for Plasma Chemistry

Deutsch, Hans‐Peter; Schmidt, Martin

doi:10.1002/ctpp.19850250508

Cited by 29 publications

(4 citation statements)

References 26 publications

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“…where the ratio of experimental to calculated SF: is taken to be -100 (table 3, data set (3)). Thus for SF2 content of -0.2% in the glow, it is not unreasonable to obtain the high SFt ion intensity which we observe, Similarly for SF:, assuming that it is formed from dissociative ionization of SF,, kSF+jSFq was estimated to be 1.3 x 10-8cm3 s -I (for a = 0.17eV-3/2, b = 0.21 eV-l, = 12.7eV, c = 0.4 x 10~20m2eV-L (Deutsch and Schmidt 1985)) yielding a value for f = 0.012 or 1.2% of the SF, concentration. Although this value is somewhat higher than the value used in…”

Section: )mentioning

confidence: 53%

“…kSFf/SF1 SFJ/SFs f = --since no measured cross sections are available for electron impact ionization of SF,, and using the parameters a = 0.095 eV-'I2, 6 = 0.16eV-l, eth = 10.1 eV (table 4), and c = 0.25 X lo-" m2 e V 1 (taken from the calculated plot of Deutsch and Schmidt 1985), ki for reaction (9) was estimated to be 2.4 x 10-8cm3s-1. Then, using the following expression for the ratio of the experimental isF$ to the calculated isFIIsF6, iSFf kSF$/SF6nSF6 + kSF?lSF&SF6…”

Section: )mentioning

confidence: 99%

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A mass spectrometric study of positive and negative ion formation in an SF₆corona. I. Sources of sulphur-fluoride ions

Sauers

Harman

1992

J. Phys. D: Appl. Phys.

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The mass spectra of positive ions generated in a positive high-voltage point-to-plane corona and negative ions generated in a negative high-voltage point-to-plane corona in high-purity SF6 are reported. In the absence of added impurities the major positively- and negatively-charged ions are SF5+, SF3+, SF2+, SF+, SF6-, SF5- and F-. Evidence for the formation of SF6 corona discharge neutral by-products, SF4 and SF2, is observed from the presence of cluster ions, SFx+(SF4) and SFx+(SF2), x=2, 3. Based on analyses of predicted ion intensities from cross-section data, SF2+ and SF+ ions are attributed to SF2 in the discharge, while most of the SF3+ observed is attributed to SF4. In the case of negative ions, analyses indicate that F- is formed in the discharge at high-density normalized electric field, E/N, from both dissociative attachment of SF6 and ion conversion processes, while SF6- and SF5- are likely to be formed outside the glow. Other ions observed resulting from the presence of trace contaminants include SOF3+, SOF2+, SOF+, SOF5- and F-(HF)2. In this paper (part I) the various sources of ions produced in 'pure' SF6 corona are discussed while in part II the effects of water and SF6 neutral corona by-products on ion formation are discussed.

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Section: )mentioning

confidence: 53%

Section: )mentioning

confidence: 99%

A mass spectrometric study of positive and negative ion formation in an SF₆corona. I. Sources of sulphur-fluoride ions

Sauers

Harman

1992

J. Phys. D: Appl. Phys.

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“…The above data treatment was extended to include P, As, B, and Si atoms, was used to confirm a "fluorine anomaly" [171,[174][175][176], and served to derive empirical correction factors for previous supposedly additive cross-sections. Figure 1 in ref.…”

Section: Ionization Cross-sections Of Moleculesmentioning

confidence: 99%

High-temperature mass spectrometry: Instrumental techniques, ionization cross-sections, pressure measurements, and thermodynamic data (IUPAC Technical Report)

Drowart

Chatillon

Hastie

et al. 2005

Pure and Applied Chemistry

234

184

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An assessment of high-temperature mass spectrometry and of sources of inaccuracy is made. Experimental, calculated, and estimated cross-sections for ionization of atoms and inorganic molecules typically present in high-temperature vapors are summarized. Experimental cross-sections determined for some 56 atoms are generally close to theoretically calculated values, especially when excitation–autoionization is taken into account. Absolute or relative cross-sections for formation of parent ions were measured for ca. 100 molecules. These include homonuclear diatomic and polyatomic molecules, oxides, chalcogenides, halides, and hydroxides. Additivity of atomic cross-sections supplemented by empirical corrections provides fair estimates of molecular cross-sections. Causes of uncertainty are differences in interatomic distances and in shapes of potential energy curves (surfaces) of neutral molecules and of molecular ions and tendency toward dissociative ionization in certain types of molecules. Various mass spectrometric procedures are described that render the accuracy of measured thermodynamic properties of materials largely independent of ionization cross-sections. This accuracy is comparable with that of other techniques applicable under the conditions of interest, but often only the mass spectrometric procedure is appropriate at high temperatures.

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“…This is a consequence of the enhanced efficiency with which singly and multiply charged ions other than C + 70 are produced from C 70 . We also note that the simple additivity rule [17,18] fails completely in this case, it would predict values more than three times higher than what is actually observed.…”

Section: A Absolute Ionization Cross Sectionsmentioning

confidence: 42%

Electron impact ionization and dissociation of neutral and charged fullerenes

Matt

Echt

Rauth

et al. 1997

Z Phys D - Atoms, Molecules and Clusters

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Three different types of electron impact ionization experiments have been performed, involving neutral and charged C 60 and C 70 . 1) We have determined absolute partial ionization cross sections for formation of parent ions C z+ 60 and C z+ 70 in charge states up to z = 4, and of singly and multiply charged fragments of size n ≥ 44 and n ≥ 50 from C 60 and C 70 neutral precursors, respectively. 2) Previous appearance energy measurements of C 70 have been improved and extended to z = 5; ionization energies are found to depend linearly on the charge state of the precursor, in agreement with theoretical predictions. 3) A beam of mass selected C 2+ 60 has been crossed with an intense electron beam; the induced reactions (fragmentation, post-ionization, and dissociative post-ionization) have been analyzed.

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Ionization Cross Sections of Gas Molecules for Plasma Chemistry

Cited by 29 publications

References 26 publications

A mass spectrometric study of positive and negative ion formation in an SF₆corona. I. Sources of sulphur-fluoride ions

A mass spectrometric study of positive and negative ion formation in an SF₆corona. I. Sources of sulphur-fluoride ions

High-temperature mass spectrometry: Instrumental techniques, ionization cross-sections, pressure measurements, and thermodynamic data (IUPAC Technical Report)

Electron impact ionization and dissociation of neutral and charged fullerenes

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Ionization Cross Sections of Gas Molecules for Plasma Chemistry

Cited by 29 publications

References 26 publications

A mass spectrometric study of positive and negative ion formation in an SF6corona. I. Sources of sulphur-fluoride ions

A mass spectrometric study of positive and negative ion formation in an SF6corona. I. Sources of sulphur-fluoride ions

High-temperature mass spectrometry: Instrumental techniques, ionization cross-sections, pressure measurements, and thermodynamic data (IUPAC Technical Report)

Electron impact ionization and dissociation of neutral and charged fullerenes

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A mass spectrometric study of positive and negative ion formation in an SF₆corona. I. Sources of sulphur-fluoride ions

A mass spectrometric study of positive and negative ion formation in an SF₆corona. I. Sources of sulphur-fluoride ions