Half-collision model for triple photoionization of lithium

Abstract

We present a simple half-collision model that allows the approximate calculation of absolute cross sections for triple ionization as well as cross-section ratios ${\ensuremath{\sigma}}^{3+}/{\ensuremath{\sigma}}^{2+}$ of lithium by photon impact. The model decomposes the three-electron breakup process into a double ionization of the two inner electrons followed by electron-electron half-scattering of the receding electrons at the residual ``spectator'' $2s$ electron. We find surprisingly good agreement with recent experimental data.