Near UV photodissociation of CD3SCD3:: CD3 fragment (v, J) vector correlations

The alignment of CD3 fragments following the photodissociation of fully deuterated dimethyl sulfide (CD3SCD3) on the first absorption band (at 219 nm) has been characterised using (2 + 1) resonance-enhanced multiphoton ionization (REMPI) spectroscopy. Operation of the time-of-flight (TOF) mass spectrometer with a low ion extraction field rejects off-axis travelling CD3 fragments, allowing velocity-selected REMPI spectra to be obtained. The strong dependence of the REMPI signal on the polarization of the probe laser is adequately explained by an impulsive model dissociation where the fragments recoil axially along the CD3S-CD3 bond. In general, the methyl fragments are found to be preferentially spinning about their C-3 axis after photodissociation, correlating with zero-point torsional vibrational motion of the parent molecule. (C) 2003 Elsevier Science B.V. All rights reserved.