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Abstract
The effect of initial vibrational excitation on Li2(n,J) + Na collisions was studied exptl. and theor. The relative integral cross sections s(n,J) were measured in a crossed beam expt. for vibrational states n populated thermally or by optical pumping, and for final states detected by laser induced fluorescence. It is found that s(n,J) increases by 35 +- 7% between n = 0 and n = 20, while the ...
Abstract
The effect of initial vibrational excitation on Li2(n,J) + Na collisions was studied exptl. and theor. The relative integral cross sections s(n,J) were measured in a crossed beam expt. for vibrational states n populated thermally or by optical pumping, and for final states detected by laser induced fluorescence. It is found that s(n,J) increases by 35 +- 7% between n = 0 and n = 20, while the dependence on the initial rotational state J is insignificant, within +-5%. The effect of vibrational enhancement is about twice as large as that found for the Li2-rare gas systems for the same amt. of vibrational excitation. The effect is about an order of magnitude larger than predicted by the authors' quasiclassical trajectory calcns. on a LEPS potential energy surface, thus suggesting that addnl. long-range potential terms ought to be included. The authors also attempted to measure state-selectively the LiNa (n',J') products from the thermal reaction and found an upper limit of the reactive cross section of 1 .ANG.2. This contrasts with the trajectory calcns. that predict a 20 times larger cross section; the authors thus conclude that the reactive part of the potential also needs to be re-evaluated.