Excitation transfer during slow collisions in a dense gas

M. I. Chibisov

Nikolai N. Bezuglov, V. M. Borodin, Andrey N. Klyucharev +2 more

A. A. Bobrov, S. A. Saakyan, B. B. Zelener +1 more

We study non-radiative dipole-dipole induced excitation transfer in dense Rb vapour. We show that density dependence of characteristic time of the excitation diffusion changes from linear to non-linear for high Rb density. It is attributed to the breakdown of binary collisions approach to the dipole-dipole excitation transfer. It is shown that the observed result can be qualitatively described if the mean free path is replaced by mean interatomic distance for the chracteristic diffusion length.

Boris Michailovich Smirnov

Ramakrishnan Chelakara Parameswaran

Pamela N. Münster, J Marek

Cross sections of excitation transfer between the fine-structure sublevels of Cs(7 2 P), Rb(6 2 P) and Rb(7 2 P) induced by collisions with rare-gas atoms have been determined from the time dependence of the sensitised fluorescence. The Cs and Rb atoms, contained in absorption cells filled with inert gases at different pressures, were excited using a pulsed dye laser pumped by a nitrogen laser. The fluorescence was observed time resolved employing a photon counting technique. The use of a two-level approximation allowed the Maxwellian (velocity) averaged transfer cross sections to be calculated. Comparison of the cross section values determined in this work with the values quoted by other authors shows good consistency in the case of Rb 6 2 P inert-gas collisions while in the case of Cs 7 2 P inert-gas collisions there are some discrepancies. Rb 7 2 P excitation transfer has not been dealt with before.