Probing of the hot-band excitations in the photodissociation of OCS at 288 nm by DC slice imaging

The photodissociation dynamics of OCS at 288 nm has been investigated using the DC (direct current) slice imaging technique, which is a recently developed high-resolution "slicing" approach that directly measures the central slice of the photofragment distribution in imaging experiments. By analyzing a DC sliced image of S(¹D₂) photofragments we observe dissociation originating from OCS molecules excited up to v₂ = 4 in the molecular beam. The measured translational energy distribution was used to determine the branching ratio for the contribution from each initial bending state (0 v₂ 0) of OCS and relative photodissociation cross section ratios compared to v₂ = 1. Large negative anisotropy parameters determined as a function of the S(¹D₂) fragment recoil speed indicate that the photodissociation of OCS at 288 nm occurs exclusively from the 1¹A″(¹Σ^-) bending excited potential surface that can be accessed through a perpendicular transition.