Comparison of trap-loss collision spectra forRb85andRb87

Abstract
We present measurements of excited-state trap-loss collisions of optically trapped Rb85 and Rb87 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, Rb87 collisions occur at a substantially lower rate than those of Rb85. 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.