The influence of an applied electric field on state changing in collisions between laser excited Xe(nf) atoms and xenon target gas is described. The presence of the field results in marked changes in both the rate constant for collisional state changing and the final-state distribution. The changes can be generally understood in terms of energy-transfer arguments based on the “essentially-free” electron model, although the degree of spatial overlap between the wave functions associated with the initial and final states may also be important.
In recent years many studies of state changes in thermal collisions between Rydberg atoms and various atomic and molecular targets have been reported. These studies were undertaken in near-zero electric fields. However, atoms in high Rydberg states are significantly perturbed by even relatively small electric fields such as are present in many environments, e.g., plasmas, where collisions occur. It is therefore of interest to study the influence of an applied dc electric field on state-changing collisions. In this paper we describe the results of such an investigation, considering as a specific example Xe(31f)-Xe collisions. The collision products are analyzed by selective field ionization (SFI). The data show that the presence of even a modest applied dc electric field results in marked changes in both the rate constant for collisional state changing and in the final-state distribution. These changes are consistent with those expected from consideration of energy-transfer arguments based on the “essentially-free” electron model. However, the data also suggest that the spatial overlap between the wave functions associated with the initial and final states may be important.
