QUANTUM YIELDS OF H(S-2) AND CH3S((2)E) FROM THE PHOTOLYSIS OF SIMPLE ORGANOSULFUR COMPOUNDS AT 193-NM, 222-NM, AND 248-NM

The primary quantum yields for the formation of H(S-2), Phi(H), and CH3S((2)E), Phi(CH3S), in the photodissociation of methyl mercaptan, dimethyl sulfide (DMS), and dimethyl disulfide (DMDS) at the excimer laser wavelengths of 193, 222, and 248 nm were measured. Phi(H) were measured using resonance fluorescence detection of H atoms. The Phi(H) were 0.55 +/- 0.04 at 193 nm, 0.98 +/- 0.15 at 222 nm, and 1.09 +/- 0.25 at 248 nm for methyl mercaptan; <0.02 at 222 nm and <0.03 at 193 nm for DMS; and <0.06 at 222 nm and <0.08 at 193 nm for DMDS. No H atom production was observed in the 248 nm photolysis of DMS and DMDS. Using a selectively deuterated methyl mercaptan sample, CH3SD, it was shown that C-H bond scission is negligible in CH3SH photolysis at 193 and 248 nm. The Phi(CH3S), measured by CH3S detection via pulsed laser-induced fluorescence, were 0.93 +/- 0.21 at 248 nn and 0.78 +/- 0.10 at 193 nm for DMS; 1.65 +/- 0.38 at 248 nm and 1.20 +/- 0.14 at 193 nm for DMDS; and 0.48 +/- 0.10 at 193 nm for methyl mercaptan. The nature of the photodissociation processes in these sulfur compounds is discussed in light of the present measurements and the results of past studies.