Ultraviolet photodissociation dynamics of the SH radical

摘要

Ultraviolet (UV) photodissociation dynamics of jet-cooled SH radical (in X (2)Pi(3/2), nu(')=0-2) is studied in the photolysis wavelength region of 216-232 nm using high-n Rydberg atom time-of-flight technique. In this wavelength region, anisotropy beta parameter of the H-atom product is similar to-1, and spin-orbit branching fractions of the S(P-3(J)) product are close to S(P-3(2)):S(P-3(1)):S(P-3(0))=0.51:0.36:0.13. The UV photolysis of SH is via a direct dissociation and is initiated on the repulsive (2)Sigma(-) potential-energy curve in the Franck-Condon region after the perpendicular transition (2)Sigma(-)-X (2)Pi. The S(P-3(J)) product fine-structure state distribution approaches that in the sudden limit dissociation on the single repulsive (2)Sigma(-) state, but it is also affected by the nonadiabatic couplings among the repulsive (4)Sigma(-), (2)Sigma(-), and (4)Pi states, which redistribute the photodissociation flux from the initially excited (2)Sigma(-) state to the (4)Sigma(-) and (4)Pi states. The bond dissociation energy D-0(S-H)=29 245 +/- 25 cm(-1) is obtained. (C) 2005 American Institute of Physics.