Study of Rydberg-atoml-changing collisions using selective field ionization

The excited products of collisions between xenon atoms and Na(nd) atoms with $n=37$ and $n=42$ have been investigated by use of selective field ionization (SFI). It is observed that, at an ionizing-field slew rate of {~} 10⁹ V/cm sec, most of the collision products follow predominantly diabatic paths to ionization which occurs at field strengths consistent with those predicted by quantum mechanical tunneling calculations. Detailed analysis of the SFI data indicates that the collision products have a wide (possibly complete) range of values of l and mⱼ, although it is not clear whether the observed distribution results from single or multiple collisions. No evidence of n-changing collisions was seen. Similar data for collisions involving Xe(nf) atoms are briefly discussed.