Rotational Energy Transfer in Highly Excited States of Lithium Dimer: Experiment and Modeling

Abstract

We report level-resolved rate coefficients for collision-induced rotational energy transfer in the 7Li2 *–Ne system, with 7Li2 * in the highly electronically excited E(3)1Σg +(v i = 4, j i = 31) and F(4)1Σg +(v i = 10, j i = 31) states. The distributions of rate coefficients are strikingly different from those previously measured for the A(1)1Σu +(v i = 2–24, j i = 30) state of the same molecule, falling off much more rapidly with increasing rotational quantum number change |Δj|. The reason for the difference was explored by means of an inverse Monte Carlo approach employing classical trajectories and a model potential, which was adjusted to give agreement with experiment. The modeling strongly suggests that the E and F state interaction potentials are much more nearly isotropic than that of the A state. The resulting dramatic reduction in rate coefficient, especially for large |Δj|, may be relevant in the relaxation of gases at high temperatures.

Quasiresonant Regimes In Li2-xe Collisions

“…Given the population ratios for a given initial and final state as determined above for each pressure, we then perform a pressure analysis to obtain the rate constants in the zero-pressure limit. This analysis has been described in great detail elsewhere [25], and will be only briefly summarized here.…”