Electron-impact ionization of CCl4 and CCl2F2

Abstract

Absolute partial and total cross sections for electron-impact ionization of CCl4 and CCl2F2 are reported for electron energies from threshold to 1000 eV. The product ions are mass analyzed using a time-of-flight mass spectrometer and detected with a position-sensitive detector whose output demonstrates that all product ion species are collected with equal efficiency irrespective of their initial kinetic energies. Data are presented for production of CCl3(+), CCl2(+), CCl+, C+, Cl2(+), and CCl3(2+) from CCl4; and for production of CCl(2)F+, CClF2(+), CClF(+), (CCl+ + CF2(+)), Cl+, CF+, F+, and C+ from CCl2F2. Data are also reported for formation of (CCl2(+),Cl+) and (CCl+, Cl+) ion pairs from CCl4. The total cross section for each target is obtained as the sum of the partial cross sections. The overall uncertainty in the absolute cross sections for most of the singly charged ions is +/- 5-7 %. The present partial cross sections for lighter fragment ions are found to be considerably greater than had been previously reported but the most recent total cross section measurements agree well with those reported here. Neither the binary-encounter-Bethe theory nor the Deutsch-Mark theory reproduces the experimental cross sections correctly for both targets.

The efficient calculation of electron impact ionization cross sections with effective core potentials

“…Experimental polarizability values are available for the lightest two molecules (CF 4 and CCl 4 ) in the series, and hence, αBEB curves were calculated. For CF 4 , this results in a cross section that is further from experimental values, whereas in the case of CCl 4 , the cross section matches the experimental values of Lindsay et al 62 within the experimental uncertainty at almost all energies.…”

Experimental investigation and modeling of the kinetics of CCl4 pyrolysis behind reflected shock waves using high-repetition-rate time-of-flight mass spectrometry

“…+ ion is unstable 15 and decomposes in less than 10 ms which would be the required flight time to reach the detector. The relative amplitudes of the fragment peaks are in good agreement with partial cross-sections determined by Lindsay et al 16 and chlorine isotopic abundance. Several series of experiments consist of about 50 with mixtures containing 0.5-1.0% CCl 4 and 0.5-1% Ar as the internal standard with Ne as bath gas were performed.…”

The role of electron scattering in electron-induced surface chemistry

“…This is consistent with gas phase ionization (whether dissociative or non-dissociative), which peaks between 70 and 150 eV. [42][43][44] This suggests that the dissociative ionization process is the same in the gas phase and in the adsorbed phase and that the surface does not play a dominant role at this energy. This is consistent with Fig.…”