Collision-induced coherence transfer between infrared molecular transitions is studied using a technique that permits the complete distribution of accompanying velocity changes to be determined in a simple way. The experiments are carried out by measuring the intensity of two pulse photon echoes as a function of applied Stark field at fixed large echo time delay. The velocity change distribution for coherence-transfer collisions is obtained directly as the shape of the echo intensity versus Stark field curve. Previously unpublished data for dipole-quadrupole and van der Waals interactions are presented, and a theory of coherence-transfer velocity-changing kernels is developed that is in good agreement with the data.

• Received 2 March 1990

DOI:https://doi.org/10.1103/PhysRevA.42.1669