Partial dissociative ionization of ${\mathrm{SF}}_6$ by electron impact using an ejected electron-ion coincidence technique

The relative differential partial ionization cross sections for the production of ionic fragments of ${\mathrm{SF}}_6$ molecule under impact of 10–20 keV electrons have been measured using an ejected electron-produced ion coincidence technique in a crossed beam apparatus with a time-of-flight analysis of the ions. The detection angle of the ejected electrons of nondiscriminated energies was kept at 90° with respect to the incident electron-beam direction. The 14 ionic fragments: ${\mathrm{SF}}_5^{+},$ ${\mathrm{SF}}_4^{+},$ ${\mathrm{SF}}_3^{+},$ ${\mathrm{SF}}_2^{+},$ ${\mathrm{SF}}^{+},$ ${\mathrm{S}}^{+},$ ${\mathrm{F}}^{+},$ ${\mathrm{SF}}_4^{2+},$ ${\mathrm{SF}}_3^{2+},$ ${\mathrm{SF}}_2^{2+},$ ${\mathrm{S}}^{2+},$ ${\mathrm{F}}^{2+},$ ${\mathrm{SF}}_3^{3+},$ and ${\mathrm{S}}^{3+}$ resulting from the dissociative ionization of the ${\mathrm{SF}}_6$ molecule were identified and their relative production cross sections have been measured. The branching ratios of 8 ionic fragments ${\mathrm{SF}}_m^{n+}$ $(m=1\mathrm{}$ to 5 and $n=1\mathrm{}$ to 3) as a function of impact energy have been determined. These ratios are found to have an almost a constant value over the considered impact energy range within the experimental uncertainty of the measurements. For the investigated impact energies, no previous data or theoretical calculations exist for a direct comparison with the present results.