HYPERFINE-STRUCTURE MODIFICATIONS OF COLLISIONAL LOSSES FROM LIGHT-FORCE ATOM TRAPS

Inelastic atomic collisions constitute loss mechanisms for neutral ato m traps, and the study of trap-loss rates may provide detailed informa tion on the long-range interaction between atoms and on the dynamics o f very slow collisions. Gallagher and Pritchard have given a simple tw o-state model for such collisions which includes a radiative transitio n or a single curve crossing at short range representing, for example, fine-structure-changing collisions. In order to better describe the m ore complicated case found in alkali metals, we have extended this mod el to include several excited hyperfine structure levels with curve cr ossings at long range. We find that collisions in a laser field that a re 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 repres ent radiative escape via the 2u potential of alkali dimer molecules we are able to greatly improve agreement between theory and experiment, including new measurements on Rb-85 reported here.