Translational energy loss spectrometry of molecular dications from methane

Abstract

Single electron loss processes have been studied in collisions of singly charged CH⁺_n ions (for n = 1-5) with Kr, CH₄, N₂ and air at impact energies in the 0.5-5 keV range. By means of translational energy loss spectrometry of product molecular ions the double ionization energies of CH, CH₂, CH₄ and CH₅ molecules have been deduced. No signal corresponding to CH²⁺₃ could be detected. Comparison is made between the present results and data obtained by means of Auger spectroscopy, double charge transfer and charge stripping in a conventional mass spectrometer as well as with recent ab initio molecular orbital calculations. Agreement between experiment and theory as well as between different experiments is generally found to be unsatisfactory.