REACTIONS OF HOT DEUTERIUM ATOMS WITH OCS IN THE GAS-PHASE AND IN OCS-DI COMPLEXES

Reactions of photolytically prepared hot deuterium atoms with OCS have been investigated: (i) under gas phase, single collision, arrested re laxation (i.e., bulk) conditions; and (ii) by photoinitiating reaction s within weakly bound OCS-DI complexes. Nascent SD (X 2PI, v=0) rotati onal, spin-orbit, and LAMDBA-doublet populations were obtained for the photolysis wavelengths 250, 225, and 223 nm by using A 2SIGMA <-- X 2 PI laser induced fluorescence (LIF). The reason for using deuterium is strictly experimental: A 2SIGMA predissociation rates are considerabl y smaller for SD than for SH. The SD (v=0) rotational distribution was found to be very cold and essentially the same for both bulk and comp lexed conditions; the most probable rotational energy is approximately 180 cm-1. No bias in LAMBDA-doublet populations was detected. Spin-or bit excitation for bulk conditions was estimated to be [2PI1/2]/[2PI3/ 2]approximately 0.25, where 2PI1/2 is the upper spin-orbit component. This ratio could not be obtained with complexes because of limited S/N The complete set of present and past experimental findings, combined with recent theoretical results of Rice, Cartland, and Chabalowski sug gest a mechanism in which SD derives from a very short lived HSCO prec ursor. This can result from direct hydrogen attack at the sulfur and/o r the transfer of hydrogen from carbon to sulfur via the HCOS intermed iate.