S2ndash;SO2energy transfer studied by matrix isolation in solid argon

摘要

Matrix samples of O2/OCS/Ar, SO2/OCS/Ar, and SO2/Ar were photolyzed with a Hg lamp over a wide range of sample concentrations. Emission spectra were recorded in both excitation and thermoluminescence with an optical multichannel analyzer. Infrared spectra of the same samples were recorded simultaneously with a PE 621 grating spectrometer. SO2was observed in IR absorption, and SO2, S2, and S atoms were observed in UVndash;Vis emission. S2fluorescence is dominant during photolysis before warmup, SO2emission is dominant during warmup from 8 to 30thinsp;deg;K, and only S2fluorescence is observed after warmup. In excitation S atom emission (1Srarr;1D) is observed simultaneously with S2fluorescence. These observations are explained in terms of an energetically coupled S2ndash;SO2complex involving rapid energy transfer between S2(Xthinsp;3Sgr;gminus;harr;BPrime;thinsp;3pgr;u/Bthinsp;3Sgr;uminus;) and SO2(Xtilde;thinsp;1A1harr;Atilde;thinsp;1B1). This same complex is also postulated to engage in energy transfer between S2(Bprime;prime;thinsp;3pgr;urarr;bthinsp;1Sgr;g) and S atoms (3P2rarr;1S). The IR spectra offer an indication of a weak (S2ndash;SO2) complex in form of a red shift of ngr;3of 8 cmminus;1compared to an SO2/Ar reference sample.