The vibrational relaxation of DCl(v=1) in liquid xenon and HCl(v=1) in liquid krypton

Abstract

The relaxation rate constants for DCl(v=1) in liquid xenon at 211 K and HCl(v=1) in liquid krypton at 190 K are reported. Both the DCl–DCl and HCl–HCl rate constants are similar to the corresponding gas phase rate constants at the same temperature, and the relaxation appears amenable to an isolated binary collision (IBC) description. As in the gas phase, the rate constant for DCl–DCl deactivation in liquid xenon is found to be smaller than that for HCl–HCl relaxation in liquid xenon, despite the smaller energy defect for the DCl relaxation process. This suggests that rotational degrees of freedom are also involved in the liquid phase vibrational relaxation of these molecules. The observed relaxation rates for DCl(v=1) by liquid xenon and HCl(v=1) by liquid krypton are found to be within an order of magnitude of values estimated from various forms of the IBC model. More careful comparisons await values of the appropriate gas phase relaxation rate constants near 200 K. Finally, certain features of the mechanism for production of vibrationally excited HCl and DCl are considered.