Impact Ionization of Rydberg Atoms by Slow Ions.
Abstract
Ionization of n=24 sodium Rydberg atoms by Na^+ impact has been studied over a reduced velocity range tilde v = v_ion/v_Bohr = 0.9 to 2.1. The corresponding ion kinetic energy range is 0.8 to 4.4 keV. Rydberg atoms were prepared by two-step laser excitation from the ground state via 3p_3/2 to 24d. Ionization events were registered by a channel electron multiplier that received free electrons corresponding to each ionizing collision directly from the beam-intersection region. Careful shielding against secondary electrons and subtraction of blackbody-ionization background from the Rydberg target were required. The relative ionization cross section shows a peak at tilde v = 1.4 and falls rapidly toward lower velocities. Results agree well with classical-trajectory calculations by Homan(D.M. Homan, unpublished) for Na^++Na(24d).
- Publication:
-
APS April Meeting Abstracts
- Pub Date:
- April 1997
- Bibcode:
- 1997APS..APR.G1582M