State-to-state photodissociation of carbonyl sulfide (v 2 =0,1∫JlM). II. The effect of initial bending on coherence of S ( 1D 2) polarization

Abstract

Photodissociation studies using ion imaging are reported, measuring the coherence of the polarization of the S (D21) fragment from the photolysis of single-quantum state-selected carbonyl sulfide (OCS) at 223 and 230 nm. A hexapole state-selector focuses a molecular beam of OCS parent molecules in the ground state (ν2 =0∫JM=10) or in the first excited bending state (ν2 =1∫JlM=111). At 230 nm photolysis the Im [a1 (1) (∥,⊥)] moment for the fast S (D21) channel increases by about 50% when the initial OCS parent state changes from the vibrationless ground state to the first excited bending state. No dependence on the initial bending state is found for photolysis at 223 nm. We observe separate rings in the slow channel of the velocity distribution of S (D21) correlating to single CO (J) rotational states. The additional available energy for photolysis at 223 nm is found to be channeled mostly into the CO (J) rotational motion. An improved value for the OC-S bond energy D0 =4.292 eV is reported. © 2005 American Institute of Physics.