Abstract: The 266 nm laser photolysis formation and chemical behavior of •HS in aqueous solution have been studied by laser photolysis-transient absorption technique. The 266 nm laser photolysis of H2O2 leads to the formation of •OH, which reacts with H2S to produce •HS, while solutions of HS− can also be directly photolyzed with 266 nm laser pulses to produce •HS radical. The transient UV-Vis absorption spectrum of •HS has been attributed to 220~300 nm with a maximum absorption at 220 nm and a shoulder at 250~270 nm. The chemical behavior of •HS is very active in oxygen saturated aqueous solution:•HS will first react with oxygen to form •SO2−, which further reacts with another oxygen molecule with the production of SO2 and •O2−. In acid solution, •O2− immediately protonates to form •HO2.

Key words: Laser photolysis- transient absorption, •, HS, Aqueous phase, H2S