Ionization of Rydberg atoms of sodium by 360–4400 eV alkali-metal ions

Abstract

Impact ionization by singly charged ions from Rydberg $\mathrm{Na}(24d)$ and $\mathrm{Na}(25s)$ states has been investigated over the reduced velocity region $\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{v}=0.5--2.2.$ The ions of ${\mathrm{Na}}^{+},$ ${\mathrm{K}}^{+},$ and ${\mathrm{Li}}^{+}$ were accelerated to energies from 360 to 4400 eV and used to bombard the laser-excited Rydberg atoms. Electrons released in the ionization of Rydberg atoms were collected from the collision volume and registered by a channel electron multiplier. Measured relative ionization cross sections from $\mathrm{Na}(24d)$ and $\mathrm{Na}(25s)$ states show maxima at $\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{v}=1.6--1.7$ and agree moderately well with classical-trajectory Monte Carlo calculations.