F. G. Kellert, K. A. Smith, R. D. Rundel, F. B. Dunning, and R. F. Stebbings Space Physics and Astronomy Depanment. Rice University. Houston. Texas 77001 (Received 20 August 1979; accepted 23 October 1979)
In thermal collisions between Xe(nf) Rydberg atoms and NH3 collisional depopulation of the nf state occurs through at least three distinct mechanisms: n -changing collisions. I-changing collisions. and ionizing collisions. Using selective field ionization we have measured the total collisional depopulation rate constants kd for laser-excited Xe(nf) atoms in the n range of 22 to 39. The magnitudes of kd are large, corresponding to reaction cross sections comparable to the geometric size of the Xe(nf) atom at n – 22. In the n range of 25 to 40, Xe + ion production provides an absolute measure of the rate constants for collisional ionization. Approximate rate constants for n – and I-changing collisions are also presented for the 31f state. In these experiments we find that the state-changing collision rate constants are fairly independent of n and are determined largely by the I-changing collisions. The collisional ionization rate constants measured are smaller than the state-changing rate constants and increase with increasing n. ranging between 0.2 and 4.6 X 10- 7 cm3 /sec for n between 25 and 40. The present results are compared to those of recent theoretical calculations .•
EFS Comments: Speaks to exited state equilibrium effects.
