Two-color spectroscopy of colliding ultracold atoms

We present experimental results of two-color photoassociative ionization (TCPAI) spectroscopy in a magneto-optical trap. A probe light beam traces out the frequency (and intensity) dependence of TCPAI. By manipulating the intensities of the trap and repumper lasers we investigate the participation of different hyperfine ground-state levels and demonstrate the conditions under which molecular bound states figure in the collision intermediate.