Distorted-Wave Calculation of Electron Impact Excitation of the Rare Gases

Abstract

A distorted-wave (DW) formulation with exchange is given for the electron impact excitation of the rare gases from ${\left(n_{0}p\right)}^6$ to ${\left(n_{0}p\right)}^5\mathrm{nl}$ configurations. A practical form employing the pure $\mathrm{LS}$-coupling scheme is used in conjunction with the phenomenologically determined independent-particle model (IPM) and the DW potentials of real central forms to compute cross sections averaged over fine structures. Numerical work is carried out for $\mathrm{Ne} 2p\to 3s$ and $\mathrm{Ar} 3p\to 4s$ electron impact excitations. The distorted generalized oscillator strengths (DGOS), which converge to the generalized oscillator strengths (GOS) in the limit of the Born approximation, as well as integrated cross sections, are obtained over a wide range of energies, so that the systematic variation of the cross sections in relation to the results of the Born approximation can be studied. The results of the angular distributions at lower energies are in reasonable agreement with the data by Nicoll and Mohr.