STATE-TO-STATE VIBRATIONAL PREDISSOCIATION OF H2-HF AND D2-HF - DIRECT COMPARISONS BETWEEN THEORY AND EXPERIMENT

The optothermal detection method has been used to measure photofragment angular distributions resulting from the vibrational predissociation of both H-2-HF and D2-HF. These angular distributions show resolvable structure which can be related to the final rotational state distributions, including the scalar intermolecular rotational correlations. H-2-HF dissociates via a predominantly V-R process, while in D2-HF the open D2 vibrational channel is the main depository for the excess energy. The experimental results are compared directly with the recent time-independent close-coupling calculations of Clary [J. Chem. Phys. 96, 90 (1992)] and the time-dependent golden rule calculations of Zhang, Zhang, and Bacic [J. Chem. Phys. 97, 927; 3149 (1992); Chem. Phys. Lett. 194, 313 (1992)]. The fact that these two systems have very different dynamics, while the potential-energy surfaces are the same, is particularly useful in providing new insights into the nature of the coupling responsible for predissociation.