Photodissociation dynamics of OCS at ∼210 nm: The role of c(23A″) state

Xilin Bai; Hao Liang; Zhengfang Zhou; Zefeng Hua; Bin Jiang; Dongfeng Zhao; Yang Chen

doi:10.1063/1.4982684

Photodissociation dynamics of OCS at ∼210 nm: The role of c(2³A″) state

J Chem Phys. 2017 Jul 7;147(1):013930. doi: 10.1063/1.4982684.

Authors

Xilin Bai¹, Hao Liang¹, Zhengfang Zhou¹, Zefeng Hua¹, Bin Jiang¹, Dongfeng Zhao¹, Yang Chen¹

Affiliation

¹ Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China.

PMID: 28688418
DOI: 10.1063/1.4982684

Abstract

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 ∼210 nm shows three dissociation channels to the fragment S(¹D₂), corresponding to low, medium, and high kinetic energy release (E_T), respectively. The high E_T channel is found to be a new dissociation channel opening with photolysis wavelength at ∼210 nm. Based on the a_q^(k)(p) polarization parameters as well as the anisotropy parameters β determined from the images of S(¹D₂), the dissociation of OCS to S(¹D₂) + CO at 210 nm is concluded to involve a direct vertical excitation of the triplet c(2³A^″) state from the ground state, followed by processes as: the low E_T component arises from a non-adiabatic transition from the repulsive A(2¹A^') state to the electronic ground state X(1¹A^'); the medium E_T component arises from a simultaneous excitation to two repulsive excited states; and the high E_T component arises from the intersystem crossing from the triplet c(2³A^″) state to the repulsive A(2¹A^') state. The present study shows that, due to the strong spin-orbit coupling between the triplet c(2³A^″) state and the repulsive A(2¹A^') state, a direct excitation to c(2³A^″) significantly contributes to the photodissociation dynamics of OCS in the deep-UV region.