Pure long-range ion-pair Cs2 molecules

We performed absorption measurements in dense cesium vapor, around the Cs second principal series lines (6s --> 7p). Three satellite bands peaking at 454.3. 459.1 and 471.6 nm are found. New ab initio Cs, potential curves calculated with the inclusion of the spin-orbit interaction are used for the identification and simulation of the observed satellite bands. The 454.3 and 459.1 run satellite bands stem from avoided crossings of long-range ion-pair potential curves with long-range covalent potential curves associated with various asymptotes. Semiclassical spectral simulations of these ion-pair satellite bands show satisfactory agreement with measured spectra. (C) 2001 Elsevier Science B.V. All rights reserved.