Kinetic effects of 3–13-photon velocity-tuned resonances investigated by a time-of-flight technique

We have investigated the change in the transverse-velocity distribution of a beam of metastable argon atoms when crossed by an intense, near-resonant, standing-wave laser field. A time-of-flight technique that provides a better resolution at low velocity than the Doppler fluorescence technique used in earlier experiments has been utilized. The effect of 3–13-photon velocity-tuned (doppleron) resonances in the mean force acting on the atoms has been studied for various laser-frequency detunings and truncations of a Gaussian light beam. The experimental results have been compared with semiclassical laser cooling theory.