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 th e SO2 absorptions decreased. This suggests reactions between SO2 and the H atoms. The annealing-induced absorptions are photobleached under 488 nm irr adiation yielding an additional group of IR absorption bands. To aid the ex perimental investigations, equilibrium structures and vibrational wavenumbe rs of three isomers HSO2, trans-HOSO and cis-HOSO were calculated at the MP 2/6311++G12d.2p) and MP4/6-311++G12d,2p) levels. Comparisons between comput ational and experimental wavenumbers suggest that the two experimentally ob served groups of IR absorption bands belong to HSO2 and cis-HOSO. (C) 2001 Elsevier Science B.V. All rights reserved.