193 nm photodissociation of H2S: The SH internal energy distribution

The dynamics of H2S and D2S photodissociation at 193 nm have been investigated using an ArF excimer laser to photolyze the parent compound and a tunable, doubled dye laser to probe the energy content of the SH or DH radicals via the laser induced fluorescence technique. The SH radicals are produced with nearly Boltzmann rotational distributions characterized by temperatures of 375±15 and 220±15 °K for the SH(2Π3/2) and SH(2Π1/2) states, respectively. No vibrationally excited SH or SD fragments were observed. An upper limit on the SH(v=1)/SH(v=0) ratio of 0.005 was determined. The ratio of SH(2Π3/2) to SH(2Π1/2) was 3.75±0.20. Although roughly 20 000 cm−1 of energy is available to the fragments, the average internal energy of the SH fragments is only 320±20 cm−1. Thus, most of the available energy must appear in the relative recoil coordinate between the H and SH fragments. This observation is in good agreement with the conclusions of previous studies and with a quasidiatomic kinematic picture of the dissociation.