State changing in collisions of Rb(ns) Rydberg atoms with HF.

Rate constants for state changing in collisions of Rb(ns) Rydberg atoms (40less than or equal tonless than or equal to48) with HF molecules have been measured and have been calculated using a semiclassical approach. Agreement between the total rate constants measured experimentally and derived theoretically is very good. The results point to the near-resonant nature of n-changing collisions, but indicate that the rate constants for such reactions are less dependent on energy imbalance than suggested by calculations based on the impulse approximation.