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Abstract. We investigate collisional properties of lithium and cesium which are simultaneously confined in a combined magneto-optical trap. Trap-loss collisions between the two species are comprehensively studied. Different inelastic collision channels are identified, and inter-species rate coefficients as well as cross sections are determined. It is found that loss rates are independent of the optical excitation of Li, as a consequence of the repulsive Li * -Cs interaction. Li and Cs loss by inelastic inter-species collisions can completely be attributed to processes involving optically excited cesium (fine-structure changing collisions and radiative escape). By lowering the trap depth for Li, an additional loss channel of Li is observed which results from ground-state Li-Cs collisions changing the hyperfine state of cesium.

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We report heteronuclear photoassociation spectroscopy in a mixture of magneto-optically trapped 6 Li and 7 Li. The laser-induced decrease in the 7 Li steady-state particle number, only appearing in the presence of 6 Li, gives clear evidence of photoassociation to form 6 Li 7 Li. Hyperfine resolved spectra of the vibrational level v = 83 of the singlet state A 1 Σ + u have been taken up to intensities of 1000 W/cm 2 . The absolute resonance frequencies and the rotational constant have been measured. Saturation of the photoassociation rate has been observed for two hyperfine transitions, which can be shown to be due to saturation of the rate coefficient near the unitarity limit. Saturation intensities on the order of 40 W/cm 2 can be determined.

We report on high-resolution two-color photoassociation spectroscopy in the triplet system of magneto-optically trapped 6 Li. Photoassociation is induced from the ground-state asymptote to the v = 59 level of the excited 1 3 Σ + g state. This level is coupled to the v = 9 level of the triplet ground state a 3 Σ + u by the light field of a Raman laser. The absolute transition frequencies are measured with an iodine frequency standard and the binding energy of the ground state is determined to 24.391 ± 0.020 GHz. Strong coupling of the bound molecular states has been observed as Autler-Townes splitting in the photoassociation signal for different detunings of the Raman laser. From the splitting we determine the spontaneous bound-bound decay rate to 4.3 × 10 5 s −1 and estimate the molecule formation rate. The observed lineshapes are in good agreement with the theoretical model.