Quasiresonant Vibration↔Rotation Transfer in Atom-Diatom Collisions

We have performed an extensive level-resolved experimental study of vibrotationally inelastic collisions in this system ${\mathrm{Li}}_2^{*}(v_i,j_i)+\mathrm{Ne}\to {\mathrm{Li}}_2^{*}(v_f=v_i+\Delta v,j_f=j_i+\Delta j)+\mathrm{Ne}$, with $8\le j_i\le 76$. At high $j_i$, the rate of vibrational transfer is large, exceeding the purely rotationally inelastic rate, and extremely specific, populating only a few rotational levels per $\Delta v$. The most probable $\Delta j$ obeys the rule $\Delta j=-4\mathrm{}\Delta v$. These effects are enhanced at low collision velocity and are quite insensitive to $v_i$ and the target gas. Classical trajectory calculations reproduce these results.