COLLISION-INDUCED DISSOCIATION OF LOW-KINETIC-ENERGY IONS

Dissociative reactions of H2+, O2 +, and NO+ molecule-ions with various atoms and molecules have been measured for reactant ions having kinetic energies less than 50 eV. Initial velocity components of the reactant ions in these experiments are axial to the slit system of the analyzing mass spectrometer which serves to discriminate against charged reactants but allows for effective collection of the slow reaction products. The cross sections for the production of low-kinetic energy H+, N+, and O+ ions range from 0.01 to 1.0 Å3 near threshold. Reasonably sharp kinetic-energy thresholds for atomic ion formation measured in these experiments approximate known molecule-ion dissociation energies.