Rotational analysis of the electronic emission spectrum of the H 2 S + ion radical

Abstract

The emission spectra of H 2 S + and D 2 S + occurring in the region 400 to 500 nm have been analysed in detail. In the lower 2 B 1 state both molecules are near oblate asymmetric tops, and from the rotational constants an SH(SD) bond length of 0.135 8 nm and an HSH(DSD) angle of 92.9° are obtained. In the 2 A 1 upper state of both molecules the equilibrium angle is about 127° and the SH(SD) bond length is 0.136 9 nm. The barrier to linearity in the excited state is ca . 4400 cm -1 and transitions have been observed from levels both below and above the barrier. The two combining states are shown to be derived from an electronic II state which is split by static Renner interaction. The complicated ro-vibronic structure of the excited state is interpreted in terms of a model in which both the dynamic Renner effect and spin-orbit interaction are included. The 2 A 1 state of H 2 S + is shown to play an intermediate role between the analogous high-barrier molecules such as AsH 2 (H ca . 9000 cm -1 ), and the low barrier molecules such as NH 2 (H ca . 800 cm -1 ).