Ion scattering from state-selected Rydberg atoms

Classical-trajectory Monte Carlo calculations have been performed for collisions of protons with state-selected hydrogenic Rydberg atoms. The examples investigated were Rydberg atoms in the $n=10\mathrm{}$, $l=9\mathrm{}$ level with $m_l=0\mathrm{} \mathrm{and} 9$. The collision velocity range was 0.1 to 1.0 a.u. (2.2×${10}^7$ to 2.2×${10}^8$ cm/s). The ionization cross sections were found to be relatively insensitive to changes in the $m_l$ levels. However, the charge-transfer cross sections showed considerable enhancement if the Rydberg electron is orientated in a plane which is parallel to the direction of the incident projectile.