Dissociative ionization by electron impact. III. O+, CO+and C+from CO2

Abstract

For pt. II, see abstr. A75105 of 1973. It is demonstrated that anisotropies can exist in the angular distributions of dissociative ions produced from a polyatomic molecule by electron impact. In particular, the distributions of O⁺ and CO⁺ ions from CO₂ are found to exhibit anisotropies for incident electron energies close to their respective production thresholds. The same symmetry arguments previously used to qualitatively explain similar anisotropies in the case of diatomic molecules can also be used in this case. The C⁺ angular distribution is found to be essentially isotropic. The cross sections for the production of CO₂⁺, CO⁺, O⁺ and C⁺ are obtained for incident electron energies up to 300 eV. Large discrepancies exist between these cross section values and those obtained in other recent experiments. It is shown that predissociation via the C state is not a dominant mechanism for the production of fragment ions.