Photodissociation dynamics of dimethyl disulfide

We present the resonance Raman spectrum of dimethyl disulfide excited with 266 nm laser light. The spectrum contains a progression of ten peaks assigned to the C-S stretch mode. This suggests that the initial motion of the dissociating molecule out of the Franck-Cordon region stretches the C-S bond. This interpretation is supported by semi-empirical calculations of the first excited singlet potential energy surface. The calculations suggest the next highest excited singlet state dissociates along the S-S bond, in agreement with work at shorter wavelengths by other workers.