Photodissociation dynamics of OCS at similar to 210 nm: The role of c(2(3)A '') state

摘要

Photodissociation dynamics of carbonyl sulfide (OCS) in the deep ultraviolet region is investigated using a time-sliced ion velocity map imaging technique. The measured total kinetic energy release spectra from the photodissociation of OCS at similar to 210 nm shows three dissociation channels to the fragment S(D-1(2)), corresponding to low, medium, and high kinetic energy release (ET), respectively. The high ET channel is found to be a new dissociation channel opening with photolysis wavelength at similar to 210 nm. Based on the a(q)((k))(p) polarization parameters as well as the anisotropy parameters beta determined from the images of S(D-1(2)), the dissociation of OCS to S(D-1(2)) + COat 210 nm is concluded to involve a direct vertical excitation of the triplet c(2(3)A '') state from the ground state, followed by processes as: the low E-T component arises from a non-adiabatic transition from the repulsive A(2(1)A') state to the electronic ground state X(1(1)A'); the medium ET component arises from a simultaneous excitation to two repulsive excited states; and the high ET component arises from the intersystem crossing from the triplet c(2(3)A '') state to the repulsive A(2(1)A') state. The present study shows that, due to the strong spin-orbit coupling between the triplet c(2(3)A '') state and the repulsive A(2(1)A') state, a direct excitation to c(2(3)A '') significantly contributes to the photodissociation dynamics of OCS in the deep-UV region. Published by AIP Publishing.