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.