Rotational relaxation of HCl in an Ar matrix

Abstract For the model of HCl trapped in a two-deminsional Ar crystal the rotational relaxation is studied by treating the orientational motion of the guest molecule quantum mechanically, whereas the heavy-particle dynamics follow an appropriate classical equation of motion: The evolution of the combined defect-host system is treated self-consistently. The transfer mechanism is elucidated. The temporal behaviour of the relaxation process as a function of rotational excess energy and temperature is studied.