Electron-impact excitation of atoms in high-lying doubly excited states: Correlation effects in collision dynamics

Abstract

Based on the hyperspherical approach, we have calculated the generalized oscillator strengths and the electron-impact-excitation Born cross sections from the initial ${}_{}{}^1{}_{}{}^{}\mathrm{S}_{}^{\mathrm{e}}{}_{}{}^{}$ high-lying doubly excited states to the final ${}_{}{}^1{}_{}{}^{}\mathrm{P}_{}^{\mathrm{o}}{}_{}{}^{}$ and ${}_{}{}^1{}_{}{}^{}\mathrm{D}_{}^{\mathrm{e}}{}_{}{}^{}$ high-lying doubly excited ones. Together with the previous results on the ${}_{}{}^1{}_{}{}^{}\mathrm{S}_{}^{\mathrm{e}}{}_{}{}^{}$ ${\mathrm{-}}^1$ ${\mathrm{S}}^{\mathrm{e}}$ excitation processes, we have found a simple propensity rule that the excitation processes with Δ$n_2$=0 are most likely to take place within each manifold, i.e., the S-S, S-P, or S-D excitation process where $n_2$ is the radial bending quantum number, i.e., the number of the nodes of the bending vibrational wave functions on the body fixed frame based on the rovibrator model of the doubly excited states. In addition to the propensity rule, Δ$n_2$=0, we have also found a set of propensity rules, i.e., Δv=ΔT=0 for angular correlation and ΔA=0 for radial correlation according to the rovibrational model where v is the bending vibrational quantum number, T is the vibrational angular momentum, and A is the radial correlation quantum number.