Predissociation of the F(4) (1)Sigma(+)(g) state of Li-2

This paper reports measurements of the homogeneous predissociation of the L i-2 F (1)Sigma(g)(+) state due to electrostatic interaction with the E (1)S igma(g)(+) state. Ab initio potential energy curves have been calculated fo r both states which in the adiabatic representation show two avoided crossi ngs. However, predissociation was not previously predicted. Our experimenta l 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 hi gh resolution measurements of linewidths for a large number of F-state leve ls 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 exp erimental 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 obs ervations on the predissociation rate of a diatomic molecule and its variat ion with v and J when the interaction with the perturbing state takes place at two distinct internuclear distances. (C) 2000 American Institute of Phy sics. [S0021-9606(00)01315-5].