ULTRAVIOLET PHOTODISSOCIATION STUDY OF CH3SCH3 AND CH3SSCH3

The photodissociation processes of CH3SSCH3 at 248 and 193 nm and CH3SCH3 at 193 nm have been studied by translational spectroscopy. When excited at 248 nm, CH3SSCH3 undergoes a simple S-S bond scission to produce two CH3S fragments with an average translational energy of 33 kcal/mol. The angular distribution of the product with respect to the polarized laser is measured and fitted with an anisotropy parameter beta=1.2. It indicates that the dissociation is a fast, direct process. At 193 nm, there is only a simple dissociation channel for CH3SCH3, while CH3SSCH3 undergoes a predominant C-S bond scission with the S-S bond scission as a minor channel. No angular dependence for the primary products from both CH3SCH3 and CH3SSCH3 has been observed. The observation of S-2(+) time-of-flight spectra shows that a major fraction of CH3S2, which is internally excited when produced, undergoes spontaneous dissociation to form slow S-2 and CH3 radicals. Results obtained for the dissociation processes of both molecules at 193 nm are rationalized and comparisons with previous investigations [J. Chem. Phys. 92, 6587 (1990); 95, 5014 (1991)] are also included.