Predissociation induced by ungerade-gerade symmetry breaking in 6Li7Li molecule

In the recent sub-Doppler experiment on the B(1)Pi(u) state of the Li-2 molecule by Bouloufa et al. [J. Chem. Phys. 111, 1926 (1999)], where the dissociation of vibrational levels due to the tunneling through the potential barrier was investigated, several vibrational levels with abnormally large dissociated rates were observed in the case of the (LiLi)-Li-6-Li-7 isotopomer. This dynamical effect cannot be explained by tunneling as in the case of Li-6(2) or Li-7(2). A Simple model of coupling between B(1)Pi(u) and 1(1)Pi(g) states involving the u-g symmetry breaking for (LiLi)-Li-6-Li-7 is proposed. Rates of the B(1)Pi(u) predissociated levels due to this coupling are calculated. A good agreement with the experiment is found.