The translational energy dependence of the integral reaction cross section for Li + HF( = 0) → LiF + H

Abstract

In a crossed molecular beam study we have measured the dependence of the relative integral cross section for the reaction Li + HF( = 0, = 1.4) → LiF + H on the translational energy of the reactants (excitation function) within a range extending from 82 to 376 meV. We find an upper boundary for the translational energy threshold of <82 meV. Only the potential energy surfaces of Palmieri and Laganà (J. Chem. Phys., 1989, 91, 7303; latest version: Parker et al., J. Chem. Phys., 1995, 102, 1238) and Aguado et al. (J. Chem. Phys., 1997, 107, 10085) are compatible with this result. In the threshold region the excitation function exhibits a steep rise with decreasing collision energy which might be due to a peak located below the accessed energy range. Similar features have been found also in recent approximate quantum scattering calculations. Theoretical predictions for the intermediate and high energy region agree well with the data.