193 nm photolysis of H2S in rare-gas matrices: Luminescence spectroscopy of the products

Abstract

The 193 nm photolysis of hydrogen sulfide (H2S) in solid rare gases is studied at 7.5 K. In order to get the most reliable data of the photolysis process, Fourier transform (FT) infrared and time-resolved luminescence methods are used in the same experiment. The 193 nm photolysis of H2S in Ar and Kr matrices was found to be very similar to the gas phase. A kinetic scheme of H2S photolysis, which is consistent with all the experimental features, was constructed. The major channel is formation of (H+SH) pairs, which are stabilized in the matrix. Then SH radicals decompose to (S+H) pairs, providing the main source for S atoms. No experimental evidence of a cage-induced reaction H+SH→S+H2 was observed in our study, which can be connected with high probability for hydrogen-atom exit from the parent cage, and/or with high probability of the recombination reaction H+SH→H2S. The available spectroscopic information for S atoms and SH radicals in Ar and Kr matrices is further specified, and new spectroscopic data on the photolysis products in Ne and Xe matrices are reported. In particular, the luminescence data on SH radicals in solid rare-gas matrices (Ne, Ar, Kr, and Xe) were found to resemble the tendencies known for OH radicals. Also, the infrared absorptions of SH radicals in Ar and Kr matrices were identified to be at 2607 and 2594 cm−1, respectively, and a novel rare-gas molecule HXeSH with the Xe–H stretch at 1119 cm−1 was detected.