Photodissociation dynamics of dimethyl sulfide following excitation within the first absorption band

The technique of resonance-enhanced multiphoton ionization with time-of-flight mass spectrometry (REMPI-TOF MS) has been used to study the photodissociation of fully deuterated dimethyl sulfide (CD3SCD3) following excitation at several wavelengths within the first absorption band (215-229 nm). Analysis of measured time-of-flight profiles of the nascent CD3 products indicates a strongly anisotropic photodissociation, with approximately 70-80% of the available energy appearing as fragment recoil translation. A hybrid statistical-impulsive dissociation model predicts a photolysis wavelength dependence of the translational energy release that compares favorably with experiment, supporting the suggestion (Manaa, M. R.; Yarkony, D. R. J. Am. Chem. Soc. 1994, 116, 11444) that both the 1(1)A" and 2(1)A" excited states play an important role in the photodissociation process. An analysis of nascent CD3 (mu, v, J) vector correlations, where the fragments are assumed to recoil axially along the CD3S-CD3 bond, adequately accounts for the observed probe laser polarization dependence of velocity-selected REMPI spectra. The weak observed rotational excitation of the methyl fragments originates from zero-point vibrational motion of the dissociating parent molecule.