[Show abstract][Hide abstract] ABSTRACT: Various additivity rules and the Deutsch—Märk (DM) formalism have been used to calculate total absolute electron-impact cross-sections for single ionization of the CFx (x = 1–3) free radicals, the NFx (x = 1,2) free radicals and the NF3 molecule. A comparison is made with experimentally determined total single ionization cross-sections which have been obtained from recently measured absolute partial ionization cross-sections for the parent and dissociative ionization of these species. The overall best agreement between the measured and the calculated cross-sections in terms of the absolute values, the shapes and the cross-section ordering was obtained using a recently proposed “new” additivity rule. Common trends and tendencies in the ionization cross-sections within each class of targets, CFx and NFx, and between the two target families CFx and NFx are highlighted and a comparison will be made with the previously measured and calculated ionization cross-sections for the SiFx (x = 1–3) free radicals.
No preview · Article · Oct 1994 · International Journal of Mass Spectrometry and Ion Processes
[Show abstract][Hide abstract] ABSTRACT: Using the recently developed semiclassical DM approach we have calculated the absolute electron impact cross sections for single ionization of some selected molecular radicals (CHn=1-3 and SiFn=1-3) from threshold up to 80 eV. The present results confirm (i) a previously noted anomaly in the ordering of the SiFn cross sections (i.e. [sigma](SiF) & >; [sigma](SiF2) & >; [sigma](SiF3)) and (ii) the failure of the simple additivity rule in predicting this anomaly.
No preview · Article · Nov 1993 · International Journal of Mass Spectrometry and Ion Processes