Line-shape analysis of resonant energy transfer collisions.

Abstract

We have investigated the resonant collision process 26{ital s}+24{ital d}{r_arrow}26{ital p}+25{ital p} in K, which occurs when the 26{ital s} and 24{ital d} states are tuned by a static electric field so that the intervals 26{ital s}-26{ital p} and 24{ital d}-25{ital p} are equal. Resonant collision line shapes are observed and analyzed for three collision velocity distributions: a thermal beam, a small band of velocities in a laser-cooled beam, and two well-separated velocity groups in a laser-cooled beam. Collisions between atoms with a broad distribution of relative velocities produce cusp line shapes. In contrast, collisions occurring between atoms in two well-defined velocity groups produce approximately Lorentzian line shapes. {copyright} {ital 1996 The American Physical Society.}