GENERAL ANALYTICAL FORM FOR THE LONG-RANGE POTENTIAL OF THE (NS-6(2)(NP(J)) 0(U)(+) STATES OF ALKALI DIMERS APPLIED TO LI)

The pooling of high-resolution laser-induced fluorescence measurements with photoassociation binding energies in Li-6(2) has provided a stri ct test of models proposed for extrapolation of long-range molecular p otential functions. An analytical expression is given for the long-ran ge part of the O-u(+) molecular states originating from M(ns(2)S) + M( np(2)P) alkali-metal atoms, replacing earlier expressions which assume d negligible spin-orbit coupling. The success of this model is illustr ated by the excellent agreement between the experimentally determined dissociation energy D-e = 9352.032(8) cm(-1), and the value 9352.032(1 2) cm(-1) obtained by extrapolation of E(R) values of a Rydberg-Klein- Rees potential for the A (1) Sigma(u)(+) state of Li-6(2). The lifetim e of the P-2(1/2) atomic level is 27.13(2) ns.