Ultraviolet photodissociation of the SD radical in vibrationally ground and excited states

Abstract

Ultraviolet (UV) photodissociation dynamics of the SD radical in vibrationally ground and excited states (X (2)Pi(3/2), v'' = 0-5) are investigated in the photolysis wavelength region of 220 to 244 nm using the high-n Rydberg atom time-of-flight (HRTOF) technique. The UV photodissociation dynamics of SD (X (2)Pi(3/2)) from v'' = 0-5 are similar to each other and to that of SH studied previously. The anisotropy parameter of the D-atom product is approximately -1; the spin-orbit branching fractions of the S((3)P(J)) products are essentially constant, with an average S((3)P(2)) : S((3)P(1)) : S((3)P(0)) = 0.51 : 0.37 : 0.12. The UV photolysis of SD is a direct dissociation from the repulsive (2)Sigma(-) state following the perpendicular (2)Sigma(-)-X (2)Pi excitation. The S((3)P(J)) product fine-structure state distributions approach that in the sudden limit dissociation on the single repulsive (2)Sigma(-) curve, but they are also affected by nonadiabatic couplings among the repulsive (4)Sigma(-), (2)Sigma(-), and (4)Pi states. A bond dissociation energy D(0)(S-D) = 29 660 +/- 25 cm(-1) is obtained.