CLASSICAL DYNAMICS OF VIBRATIONAL TRANSFER IN LI(2)A(1)SIGMA(-NE COLLISIONS()(U))

Classical trajectory calculations on an ab initio potential surface fo r the Li-2 A (t) Sigma(u)(+)-Ne system show that vibrationally inelast ic collisions at low reagent excitation are dominated by impacts of th e atom with the side of the molecule. As molecular excitation increase s, impacts nearer the end of the molecule increase in importance. The two classes of collisions are clearly distinguishable in computed velo city-dependent cross sections, and should be observable in some cases as a bimodal angular momentum distribution in velocity-averaged rare c onstants. We discuss experimental data in light of these observations and suggest measurements that should clearly display evidence of the t wo mechanisms.