Comparison of trap-loss collision spectra for 85Rb and 87Rb.

Abstract

We present measurements of excited-state trap-loss collisions of optically trapped $^{85}\mathrm{Rb}$ and $^{87}\mathrm{Rb}$ atoms as a function of the frequency of the light used to excite the colliding atom pairs. For detunings outside the excited-state hyperfine structure, the trap-loss rates are found to be the same for the two isotopes. For detunings inside the excited-state hyperfine structure, $^{87}\mathrm{Rb}$ collisions occur at a substantially lower rate than those of $^{85}\mathrm{Rb}$. The spectra make it clear that the long-range dynamics of the collisions are strongly modified by the excited-state hyperfine structure, and that the dynamics are different for the two isotopes.