Predissociation of the F(4) 1Σg+ state of Li2

This paper reports measurements of the homogeneous predissociation of the Li-2 F (1)Sigma(g)(+) state due to electrostatic interaction with the E (1)Sigma(g)(+) state. Ab initio potential energy curves have been calculated for both states which in the adiabatic representation show two avoided crossings. However, predissociation was not previously predicted. Our experimental results show that the three isotopomers Li-7(2), (LiLi)-Li-6-Li-7, and Li-6(2) all strongly predissociate above the 2s+3s atomic limit. We report high resolution measurements of linewidths for a large number of F-state levels spread across the 2600 cm(-1) energy region between the 2s+3s and 2p+2p atomic limits, which yield systematic information regarding the rotational, vibrational, and isotopomer dependence of the predissociation rate. An experimental RKR potential energy curve for the F state is derived and used to calculate predissociation rates whose trends show good agreement with the experimental values. This paper presents the first complete data set of observations on the predissociation rate of a diatomic molecule and its variation with v and J when the interaction with the perturbing state takes place at two distinct internuclear distances. (C) 2000 American Institute of Physics. [S0021-9606(00)01315-5].