Effect of molecular bending on the photodissociation of OCS

Abstract

At 230 nm, the photodissociation of OCS via a hot band and a triplet state was investigated by selective probing of high rotational levels of product CO (J=45–67) with photofragment imaging spectroscopy: OCS(v=0)+hν(UV)→CO(X 1Σ+,J⩾65)+S(3P), OCS(v=1)+hν(UV) →CO(X 1Σ+,J∼65)+S(1D). Additional two-photon IR excitation of the UV photoprepared OCS with intense 1.06 μm laser pulses bleaches the UV processes listed above and induces a new excitation channel of OCS: OCS(v=0)+hν(UV)→OCS*, OCS*+2hν(IR)→CO(X 1Σ+,J∼74)+S(1S). The bending mode of OCS in the excited states plays a central role in the excitation and dissociation dynamics. Additionally, the alignment effect of OCS by nonresonant infrared laser pulse, which appears on the angular distribution of the photofragment, is discussed.