Absolute cross-section measurements for ionization of He Rydberg atoms in collisions with K.

Abstract

Absolute cross sections for ionization of 1.5--10.0 keV/amu Rydberg helium atoms in principal quantum states 12\ensuremath{\le}n\ensuremath{\le}15 due to collisions with potassium have been measured. The data are compared with the free-electron cross section at equal velocity. Our results for the collisional ionization cross sections (${\mathrm{\ensuremath{\sigma}}}_{\mathit{i}}$) agree both in shape and absolute magnitude with the data available for the total electron-scattering cross sections (${\mathrm{\ensuremath{\sigma}}}_{\mathit{e}}$) and support recent theoretical models for ionization of Rydberg atoms with neutral perturbers.