Vibrational relaxation of HF and DF

Relaxation times for vibration→rotation, translation deexcitation of HF(v=1) by HF(v=0) and DF(v=1) by DF(v=0) are calculated using quasiclassical trajectory techniques. An empirical interaction potential, formulated so as to give a reasonably accurate description of the hydrogen bonding in these systems, is employed in the calculations. Since the initial rotational states of the collision partners are restricted to the most probable state for each temperature investigated, only qualitative agreement with experiment is obtained. The observed temperature dependencies of the vibrational relaxation times are discussed in terms of their interdependence on the directionality of the hydrogen bonding interaction and initial molecular rotation.