Effect of short-range forces and of twisting on intramultiplet mixing in collisions of alkali-metal atoms

E. E. Nikitin

J. M. M. J. Vogels, B. Verhaar, R. H. Blok

E. I. Dashevskaya, E. E. Nikitin

We present an approximate theory of intramultiplet mixing, relaxation, and polarization transfer in excited alkali atoms, valid for all magnitudes of the fine-structure splitting. The theory is developed as the generalization of the previously postulated theory of fine-structure mixing induced in adiabatic and quasiresonant collisions. In the adiabatic region, the theory predicts a change in the sign of the coefficient for polarization transfer between the components j = 1/2 and,j = 3/2 of the 2P resonance doublet, as the Massey parameter for this transition changes.

V. M. Borodin, Andrey K. Kazansky

E. E. Nikitin, Anatoly I. Shushin

Paul D. Lett, Klaus Mølmer, S. D. Gensemer +4 more

Inelastic atomic collisions constitute loss mechanisms for neutral atom traps, and the study of trap-loss rates may provide detailed information on the long-range interaction between atoms and on the dynamics of very slow collisions. Gallagher and Pritchard (1989) have given a simple two-state model for such collisions which includes a radiative transition or a single curve crossing at short range representing, for example, fine-structure-changing collisions. In order to better describe the more complicated case found in alkali metals, we have extended this model to include several excited hyperfine structure levels with curve crossings at long range. We find that collisions in a laser field that are capable of expelling atoms from the trap can be suppressed in some laser frequency regions and enhanced in others, in comparison with the predictions of the simple two-state model. Using this model to represent radiative escape via the 2 u potential of alkali dimer molecules we are able to greatly improve agreement between theory and experiment, including new measurements on 85 Rb reported here.