Photodissociation dynamics of OCS near 128 nm: S(3PJ=2,1,0), S(1D2) and S(1S0) channels

Here we report the study of the photodissociation dynamics of carbonyl sulfide in the vacuum ultraviolet region using the time-sliced velocity map ion imaging technique. Images of S(3PJ=2,1,0), S(1D2) and S(1S0) products were measured at four photolysis wave-lengths of 129.32, 128.14, 126.99, and 126.08 nm, respectively. Four main dissociation channels: S(3PJ=2,1,0)+CO(X1Σ+), S(3PJ=2,1,0)+CO(A3Π), S(1D2)+CO(X1Σ+) and S(1S0)+CO(X1Σ+) channels, have been clearly observed and identified. Vibrational states of the CO co-products were partially resolved in the experimental images. From these images, the product total kinetic energy releases, the branching ratios and angular distributions of products have been derived. While the S(3PJ=2,1,0)+CO(A3Π) product channel is formed through the adiabatic dissociation process after the excitation to the (31Σ+) excited state, the results suggest that strong nonadiabatic coupling plays an important role in the formation of other three channels.