Laser-induced ultracold Rb(5S1/2)+Rb(5P1/2) collisions

Measurements of collisional loss of optically trapped Rb atoms are presented for excitation of the colliding atoms by light tuned near the 5${\mathit{S}}_{1/2}$→5${\mathit{P}}_{1/2}$ transitions of ${}_{}{}^{85}{}_{}{}^{}\mathrm{Rb}$ and ${}_{}{}^{87}{}_{}{}^{}\mathrm{Rb}$. Using the ${\mathit{P}}_{1/2}$ state allows the effects of spontaneous emission on excited-state collisions to be studied with minimal complications arising from hyperfine structure. The shapes of the collision spectra are nearly identical for the two isotopes and are consistent with a simple model for the role of spontaneous emission during the collision.