General analytical form for the long-range potential of the (ns+npJ)0u+states of alkali dimers applied toLi26

Abstract

The pooling of high-resolution laser-induced fluorescence measurements with photoassociation binding energies in $^{6}\mathrm{Li}_{2}$ has provided a strict test of models proposed for extrapolation of long-range molecular potential functions. An analytical expression is given for the long-range part of the ${0}_{\mathrm{u}}^{+}$ molecular states originating from M(ns${\mathrm{}}^{2}$S)+M(np${\mathrm{}}^{2}$P) alkali-metal atoms, replacing earlier expressions which assumed negligible spin-orbit coupling. The success of this model is illustrated by the excellent agreement between the experimentally determined dissociation energy ${\mathrm{D}}_{\mathrm{e}}$=9352.032(8) ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$, and the value 9352.032(12) ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ obtained by extrapolation of E(R) values of a Rydberg-Klein-Rees potential for the A${\mathrm{}}^{1}$${\mathrm{\ensuremath{\Sigma}}}_{\mathrm{u}}^{+}$ state of $^{6}\mathrm{Li}_{2}$. The lifetime of the $^{2}\mathrm{P}_{1\mathrm{/}2}$ atomic level is 27.13(2) ns.