Collisions of cold magnesium atoms in a weak laser field

We use quantum scattering methods to calculate the light-induced collisiona l loss of laser-cooled and trapped magnesium atoms for detunings up to 30 a tomic Linewidths to the red of the S-1(0)-P-1(1) cooling transition. Magnes ium has no hyperfine structure to complicate the theoretical studies. We ev aluate both the radiative and nonradiative mechanisms of trap loss. The rad iative escape mechanism via allowed (1)Sigma(u), excitation is dominant for more than about one atomic linewidth detuning. Molecular vibrational struc ture due to photoassociative transitions to bound states begins to appear b eyond about ten linewidths detuning. [S1050-2947(99)50306-5].