Photolability, measurement

A quantitative study of the rate of product formation as a function of exposure time and pressure showed that HjS and CH4 arise from secondary reactions in the photolysis, viz., sensitization of the substrate by an electronically or vlbrationally excited molecule of dimethyl disulfide the unit efficiency of the primary step was verified. Thiyl radicals were also observed by EPR and uv measurements on photol-yzed CHaSH in the solid state , in water clathrate matrices and in flash photolysis experiments . Recent evidence points to the formation of hot H-atoms in the primary process. The Hg( Pi)-sensitized decomposition of CH3SH also leads to the formation of CH3S + H but there is a minor (ca 10%) contribution from C-S cleavage, viz. 

Schematic iayout of the ID18 beamiine and the ID18F user end-station. Photodiode 1 (photol) is piaced either into the sampie position if a sampie was measured (geometry 1) or in front of the mini-ionization chamber (geometry 2). For other components, see text (Adapted from Somogyi et ai. 2003)...

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