Dissociation of energy-selected c-C3H6S+ studied with threshold photoelectron-photoion coincidence experiments and calculations

The dissociation of energy-selected c-C3H6S+ was investigated in a region 10.2-10.9 eV with a threshold photoelectron-photoion coincidence technique. Branching ratios and average releases of kinetic energy for channel c-C3H6S+ → H2CS+ + C2H4 were derived from coincidence mass spectra. The measured small releases of kinetic energy near the appearance onset agree with statistical calculations; a linearly extrapolated threshold at 10.39 ± 0.01 eV agrees with a predicted energy 10.35 eV with the Gaussian-3 method. We discuss plausible mechanisms for c-C3H6S+ dissociating to CH3CS+ + CH3 based on G3B3 calculations to rationalize the absence of CH3CS+ signal in these experiments.