Teratomic recombination of excited RbXe*

Abstract

Free Rb(5 2S) is optically excited to Rb*(5 2P1/2) in the presence of Xe gas, and the RbXe*(A 2Π1/2)-RbXe(X 2Σ1/2) fluorescence is measured as a function of xenon pressure. The teratomic recombination process, Rb* + 2Xe→RbXe* + Xe, and other collision processes compete with radiative decay. The radiative rate is known, so collisional rates can be inferred from the data. The molecular spectrum is observed as a continuum, whose intensity profile yields the bound-state vibrational distribution at each xenon pressure. The low-pressure limit of this distribution yields the teratomic recombination rate as a function of vibrational state, and the total recombination rate constant kf. The recombination rate into a bound state increases with increasing binding energy, but less rapidly than the increase in equilibrium population. The transition from this initially formed distribution to the high-pressure equilibrium distribution is reported. The ratio kf/Keq=2.4 × 10−11 cm3/sec and the equilibrium constant Keq≃3.4 × 10−21 cm3, corresponding to the experimental temperature of 300 K, are deduced from the data. The A 2Π1/2 and X 2Σ1/2 potentials are also obtained from analysis of the spectrum in the low-pressure and high-pressure limits.