Abstract
Abstract The photoionization cross section of sodium has been calculated for radiation of wavelength greater than 160 A. In the case of the 3s-ep transition the bound and free wave functions were based on a potential described by Biermann and Lubeck(1) in which a polarizability term and a term to allow for exchange are included. The contribution to the cross section from the L-shell electrons was estimated by means of the approximate formulae of Bates(2) using Hartree-Fock wave functions for the initial states and Coulombic wave functions for the final states. Both the dipole length and the dipole velocity 3s-ep transition matrix elements were evaluated. The results obtained are in good accord, the former matrix elements leading to an absorption cross section of 13.6 × 10−20 cm2 at the spectral head, the latter 12.6 × 10−20 cm2. A comparison is made with the experimental results of Ditchburn et al.(3), and the Hartree-Fock calculations of Seaton(4).
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