Absolute electron impact ionization cross sections for , whereX= H, F, Cl, Br, and I

Abstract

Measurements of electron impact ionization cross sections have been made for methane and the series methyl fluoride to methyl iodide. The results for methane and methyl fluoride to methyl bromide have been compared with ionization efficiency curves calculated using Deutsch-Märk (DM) and binary-encounter-Bethe (BEB) methods, and also with the results of an ab initio model which gives the maximum cross section as a function of molecular orientation. In addition, the ab initio and DM methods have been used to calculate the steric ratios for the electron impact ionization of methyl chloride which have been compared with experimental measurements made previously.

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

“…Another recent model free of adjustable parameters is based on a subtle combination of quantumchemical and classical concepts [187]. It postulates ionization to occur when the Coulomb potential experienced by a molecule in the electric field of an approaching electron, viewed as a point charge, equals the ionization energy.…”

“…For molecules, theoretical and semi-theoretical models have been developed for calculating ionization cross-sections [181][182][183][184][185]187]. Progress in the measurement of molecular cross-sections [146][147][148][149] is encouraging, although incomplete.…”

Adsorption geometry of methyl chloride weakly interacting with Ag(111)

“…TPD spectra were recorded with a shielded quadrupole mass spectrometer (QMS), which is described elsewhere [17], positioned 1 mm away from the sample. The QMS signal intensity was calibrated to gas phase CH 3 Cl with a relative ion gauge sensitivity factor of 2.4 [18,19]. IRAS measurements were carried out with a Fourier transform infrared spectrometer with a liquid-nitrogen cooled MCT (HgCdTe) detector.…”

Corrections to the following three papers pertaining to electron impact ionization efficiency curves calculated using the BEB model for molecules containing third and fourth row atoms

“…We would like to apologize to Y K Kim and M E Rudd, the developers of BEB theory, for unfair criticism of the performance of their model for molecules containing third and fourth row atoms. Note that the comments in this corrigendum apply only to the BEB calculations presented in [4][5][6][7], and in no way invalidate the other results and conclusions of these papers. …”

“…We have recently re-examined some published binary-encounter-Bethe [1][2][3] (BEB) calculations on the electron impact ionization cross sections for halogenated hydrocarbons [4][5][6] and sulfur-containing molecules [7]. The calculations were carried out primarily to support our experimental data.…”