Effect of Internal Excitation on the Collision-Induced Dissociation of 2000-eV Diatomic Molecule Ions

Collision-induced dissociations of 2000-eV N2+, O2+, CO+, and NO+ ions have been studied as a function of reactant ion internal energy. Relative cross sections and product ion velocity distributions for dissociative scattering processes through angles less than 2° have been examined as a function of reactant ion internal energy by changing the kinetic energy of the ionizing electrons. Product ion velocity distributions are consistent with a mechanism that assumes Franck–Condon-type transitions between electronic states of the reactant species. These dissociative reactions involving diatomic molecule ions have been used to probe the internal energy content of NO+ and CO+ ions resulting from the unimolecular decomposition of triatomic molecule ions formed by electron-impact ionization.