Absorption measurements in dense cesium vapor using a UV-violet light-emitting diode

We present results of absorption measurements in a dense superheated cesium vapor generated in an all-sapphire cell using a UV-violet light-emitting d iode as a continuum source. Due to the very effective thermal destruction o f Cs-2 molecules, a number of diffuse and satellite bands appear around hig her members of cesium principal series lines, which are not easily visible in saturated cesium vapor. From the temperature dependence of the diffuse f eatures we can distinguish short-range singlet transitions from temperature -independent spectral features that stem either from a shallow lowest tripl et state or from the long-range photo association spectra of triplet or sin glet Cs-2 molecules, The limits of the present interpretation of the observ ed bands in the UV-violet spectral region are discussed.