Adiabatic cooling of atoms by an intense standing wave

Lithium atoms channeled in the nodes of an intense standing-wave radiation field are cooled to near the recoil limit by adibatically reducing the radiation intensity. The final momentum distribution has a narrow component with a root-mean-squared momentum of 2ħk in one dimension, where ħk is the momentum of a radiation-field photon. The data are compared with the results of a Monte Carlo simulation using a two-level atom model. This process may be useful for cooling and increasing the phase-space density of atoms confined in a magnetic trap