Electron capture and dissociation of the molecule in slow collisions

Abstract

Single and multiple electron capture processes are studied in slow (8 - 16 keV) collisions between and molecular nitrogen. The contributions of dissociative and non-dissociative channels are determined as well as the kinetic energies of the fragments of the (q = 1 - 6) ions. From the kinetic energies of the fragments dissociation energies of the molecular ion are deduced. Under the assumption of isotropic dissociation the following results are obtained: at most 7% of single-electron capture leads to dissociation of into and at least 90% of the double-electron capture results in fragmentation into . If more than two electrons are captured, all -ions dissociate into . For even values of q we observe r = s, otherwise ; i.e. the maximum difference between r and s is 1. A charge distribution closest to the most symmetric one is preferred. The measured dissociation energies are smaller than those expected from the model of Coulomb explosion. Therefore, potential curves for the and molecular ions have been calculated, and dissociation energies deduced from these potential curves have been compared to the measured ones. In both cases dissociation from the lowest molecular state of the multicharged molecule seems most probable.