Quasi-Resonant Vibration−Rotation Transfer in Inelastic Li2*−Ne Collisions

We present the results of a detailed study of the influence of rotational angular momentum on vibrotational transfer in the system Li2*(Vi,ji) + Ne f Li2*(Vf,jf) + Ne, where Vi,f and ji,f indicate initial and final vibrational and rotational levels, respectively, and Li2* is in its first electronically excited 1 Σu + state. Level-to-level inelastic rate constants for ji up to 76 have been measured. The measurements span 4 orders of magnitude in size and include |∆V| e 5 and |∆j| e 50. The results extend the range of previous measurements in this system and further document the phenomenon of quasiresonant vibrotational transfer. This process, induced by high rotational angular momentum, results in large rate constants for vibrational transfer and a systematic correlation of ∆j and ∆V according to the rule ∆j )- 4∆V .A tji g 64, the total vibrationally inelastic rate constant is found to be larger than the total rotationally inelastic rate constant. A fully classical treatment of the dynamics on an ab initio potential surface results in rate constants that agree remarkably well with the data.