PHOTOASSOCIATION IN A GAS OF COLD ALKALI ATOMS .1. PERTURBATIVE QUANTUM APPROACH

We develop a quantum-mechanical approach to the photoassociation pheno menon in a sample of cold atoms initially at thermal equilibrium with temperature T. We calculate the rate of formation of molecules in the weak field regime using a perturbative approach. Analytical expression s are obtained for the overlap between the initial and final molecular wavefunctions, and are shown to agree with numerical calculations. Th e photoassociation rate is found to decrease with increasing atomic ma ss m, from Li to Cs. Also considered is the heating of the atomic samp le through spontaneous photodissociation.