Mechanism of the metastable reaction H 2S + → S + + H 2; product energy distributions and their dependence on temparature

Abstract

The fragmentation of metastable H 2S + ions to produce S + and H 2 has been investigated by mass analyzed ion kinetic energy spectrometry (MIKES). Kinetic energy release distributions have been derived from the MIKES peaks. Resolved structure is evident in the release distributions. When the metastable reaction is assigned to the specific H 2S +( 2A 1) vibronic, levels (known from fluorescence lifetime measurements to lie in the metastable lifetime range) good correlation is found between the position of the structure in the distributions and predicted transition energies. The data indicate that substantial rotational excitation of the product H 2 is occurring. The average kinetic energy released in the metastable fragmentation was found to increase with ion source temperature. This increase in kinetic energy with temperature is ascribed to the release of the increase in rotational energy of H 2S + as relative kinetic energy of the metastable products. A detailed analysis of the mechanism for the metastable reaction is given.