Ion-collision spectrometric study of the dissociation dynamics of S2+ and CS+ radicals

Collision-induced dissociation experiments on ground-state S2+ and CS+ have been carried out using a crossed-beam ion translational energy spectrometer with a very high angular resolution (≤10-4 rad). The distributions of kinetic energies released upon dissociations S2+→S++S, CS+→S++C, and CS+→C++S in 3-keV collisions with N2 have been measured; dissociation channels have been identified with the aid of computer simulations of trajectories through the apparatus of ions possessing different center-of-mass kinetic-energy release (Kc.m.) components. In the case of S+ formation from S2+, dissociation occurs via excitation to repulsive S2+* electronic states, giving rise to Kc.m. components of 1.5 and 2.0 eV; lower Kc.m. values (0 and 0.3 eV) are obtained upon dissociation of a bound excited state of S2+ by a curve-crossing mechanism. Dissociation of CS+ occurs via rotational resonances, giving rise to narrow, symmetrical structure in the S+ translational energy spectrum; direct dissociation also occurs which yields relatively high Kc.m. values due to the breaking of the strong C≡S triple bond. The CS+→C++S channel is considerably weaker