State-to-State Vibrational Predissociation Dynamics of the Acetylene-HCl Complex

Photofragment translational spectroscopy has been implemented to obtain correlated final state distributions for the acetylene-HCl complex. Vibrational predissociation is induced by exciting the asymmetric acetylene C-H stretching vibration. In contrast with previous studies of this system, which suggested that the primary dissociation channel involves intermolecular V-V energy transfer (resulting in the production of v = 1 HCl), the present study shows that the dominant channel involves intramolecular V-V energy transfer, with the majority of the excess energy remaining with the acetylene subunit. In fact, the dissociation energy determined in the present study, D = 830 ± 6 cm, indicates that the HCl (v = 1) channel is closed.