Rate coefficients measurement for the energy-pooling collisions Cs(5D) + Cs(5D) → Cs(6S) + Cs(nl = 9D, 11S, 7F)

We report experimental rate coefficients for the energy-pooling collisions Cs(5D) + Cs(5D) → Cs(6S) + Cs(nl = 9D, 11S, 7F). In the experiment the Cs(5D) state was populated via photodissociation of Cs2 molecules using an argon-ion laser at wavelength 488.0 nm. We also consider the competing process 6P1/2 + 7S → 6S + (nl = 9D, 11S, 7F) that might also populate 9D, 11S and 7F. An intermodulation technique was used to select the fluorescence contributions due only to the process 6P1/2 + 7S → 6S + (nl = 9D, 11S, 7F). The excited atom (nlJ) density and spatial distribution were mapped by monitoring the absorption of a counterpropagating probe laser beam tuned to various nlJ→n′lJ′′ transitions. The measured excited atom densities are combined with measured fluorescence ratios to yield rate coefficients for the energy-pooling collisions Cs(5D) + Cs(5D) → Cs(6S) + Cs(nl = 9D, 11S, 7F). The rate coefficients for nl = 9D, 11S, 7F are (4.1 ± 2.0) × 10−10 cm3 s−1, (1.6 ± 0.8) × 10−10 cm3 s−1 and (3.6 ± 1.8) × 10−10 cm3 s−1, respectively. The contributions to the rate coefficients from other energy transfer processes are also discussed.