Dependence of level‐resolved energy transfer on initial vibrational level in Li2A1Σu+−Ne collisions

We have investigated collision induced rotational and vibrational energy transfer in the Li2 A1Σu+(vi,ji=30)−Ne system experimentally under single‐collision conditions at an effective temperature of 691 K. Over 800 inelastic rate constants have been measured, with the initial vibrational level vi ranging from 2 to 24 and −2≤Δv≤+2. Increasing vi results in a linear increase in the vibrational transition rate constants, which is accompanied by a decrease in the rotationally inelastic transition rate constant. The total inelastic rate constant increases with vi only at the highest values of vi. Net vibrational energy transfer 〈ΔE〉 calculated using rotationally summed rate constants is qualitatively consistent with a simple model. However, explicit inclusion of rotation gives quite different values of 〈ΔE〉. The experimental results are compared with our three‐dimensional trajectory calculations on an ab initio potential surface and on a simple repulsive potential surface.