Photochemistry of H2S/SO2 mixtures in solid krypton

The H2S/SO2/Kr samples at 7.5 K were photolysed by UV irradiation, and H2S decomposed producing in particular hydrogen atoms. In subsequent annealing at 30 K, a number of new IR absorptions were observed and simultaneously the SO2 absorptions decreased. This suggests reactions between SO2 and the H atoms. The annealing-induced absorptions are photobleached under 488 nm irradiation yielding an additional group of IR absorption bands. To aid the experimental investigations, equilibrium structures and vibrational wavenumbers of three isomers HSO2, trans-HOSO and cis-HOSO were calculated at the MP2/6311++G12d.2p) and MP4/6-311++G12d,2p) levels. Comparisons between computational and experimental wavenumbers suggest that the two experimentally observed groups of IR absorption bands belong to HSO2 and cis-HOSO. (C) 2001 Elsevier Science B.V. All rights reserved.