Correlation of Cs/foreign gas diffuse bands with theoretical interaction potentials

Abstract Fluorescence excitation is employed to survey diffuse spectral bands in mixtures of Cs with He, Ne, Ar, Kr, Xe, or N 2 over the wavelength range 430–470 nm. Direct fluorescence and sensitized fluorescence at low pressures are also utilized to associate various diffuse bands with their respective atomic parent lines. The line-band associations, along with the positions and strengths of the bands, are then correlated with theoretical potentials for the collision pairs. The potentials exhibit a rich structure in the excited state which qualitatively describes many of the diffuse band characteristics and lead to the following conclusions: (1) red satellite bands are correlated with long-range (20–30 a.u.) shallow potential wells in the excited state, (2) violet satellite bands are correlated with maxima in the excited state potentials in the range 10–20 a.u., and (3) detached bands are formed near avoided crossings in the range 6–10 a.u. A diagnostic technique for foreign gas density is also demonstrated for N 2 and He.