Coriolis-induced vibrational energy transfer in D2CO-D2CO collisions. II. A semiclassical sudden approximation

Recent experimental studies of vibrational energy transfer in D₂ CO-D₂ CO collisions have demonstrated extraordinarily high cross sections for an intramolecular V-V process in which a vibrational quantum is transferred between the two coriolis-coupled modes ν₄ and ν₆ . In this paper a simple semiclassical theory of this process is presented. The theory combines a resonance Hamiltonian originally derived by Burleigh, Mayrhofer, and Sibert, and by Gray and Davis, with a classical-path treatment of translation. With the aid of a time-dependent sudden approximation, applied not to molecular rotation but to the 3.5 cm^-1 energy gap between perturbed molecular eigenstates, opacity functions, and absolute cross sections can be calculated in closed analytic form. Agreement with experiment is surprisingly good.