Vibrational state-specific nonadiabatic photodissociation dynamics of OCS⁺ via A²_1/2 (₁ 0 ₃) states

The identification and analysis of quantum state-specific effects can significantly deepen our understanding of detailed photodissociation dynamics. Here, we report an experimental investigation on the vibrational state-mediated photodissociation of the OCS+ cation via the A(2)Pi(1/2) (nu(1) 0 nu(3)) states by using the velocity map ion imaging technique over the photolysis wavelength range of 263-294 nm. It was found that the electronically excited S+ product channel S+(D-2(u)) + CO (X-1 Sigma(+)) was significantly enhanced when the nu(1) and nu(3) vibrational modes were excited. Clear deviations in the branching ratios of the electronically excited S+ channel were observed when the vibrational modes nu(1) and nu(3) were selectively excited. The results reveal that vibrationally excited states play a vital role in influencing the nonadiabatic couplings in the photodissociation process.