Thermochemistry and energy partitioning in the charge separation reactions of doubly charged triatomic ions

Abstract

Ion kinetic energy and appearance potential measurements have been used to study the unimolecular charge separation reactions of the triatomic ions ${\mathrm{CO}}_2^{\text{2+}}$ , COS²⁺, ${\mathrm{CS}}_2^{\text{2+}}$ , N₂O²⁺, ${\mathrm{NO}}_2^{\text{2+\hspace{0.17em}·}}$ , and ${\mathrm{SO}}_2^{\text{2+}}$ . The experimentally determined metastable peak shapes have been compared with calculated peak shapes including calculations that determine both the average kinetic energy release and the distribution about this average. The product ion states have been assigned from the thermochemical data, and in all the reactions total spin and angular momentum are found to be conserved. There is evidence that the metastable peaks are associated with maxima on single potential surfaces rather than with a slow predissociation. For ${\mathrm{CO}}_2^{\mathrm{++}}$ and COS⁺⁺ almost all the available energy is partitioned into translational energy of product separation.