photodissociation of vibrationally excited SH and SD radicals at 288 and 291 nm:The S(1D2) channel

摘要

Ultraviolet photodissociation of SH (X 2II,V"=2-7) and SD (X 2II,v"=3-7) has been studied at 288 and 291 nm,using the velocity map imaging technique to probe the angular and speed distributions of the S(1D2) products.Photodissociation cross sections for the A 2SUM+<- X 2II(v') and 2DELTA<-X2II(v") transitions have been obtained by ab initio calculations at the CASSCF-MRSDCI/ aug-cc-pV5Z level of theory.Both the experimental and theoretical results show that SH/SD photodissociation from X 2II (v'<=7) proceeds via the repulsive wall of the A 2SUM+ state.The angular distributions of S(1D2) indicate that the dissociation approaches the sudden recoil limit of the A 2SUM+ state,yielding strongly polarized fragments.The S(1D2) atoms are predominantly produced with total electronic angular momentum perpendicular to the recoil axis.