Relative excitation cross sections of the lowest-lying autoionizing state 2p 5 3s 2 2 P of sodium are measured for electron impact in the range of incident energy E 0 from 1.5 keV down to the threshold. Absolute cross sections are obtained by normalization of the relative cross sections at E 0 = 1.5 keV to the theoretical cross section in the plane-wave Born approximation with accurate atomic wavefunctions. Negative ion resonances near the excitation threshold are observed and reproduced by a 26-state R-matrix calculation. The cross sections at intermediate incident energies are obtained in the distorted-wave Born approximation and are compared with the present experimental values and with theoretical values of other authors.
We have measured the alignment A20 of K*(3p54s2 2P3/2) and the ratio of cross sections R0 = sigma (3/2)/ sigma (1/2) of fine structure states K*(3p54s2 2P3/2, 2P1/2) for electron impact excitation in the range of incident energy E0 = 31.4-500 eV. We have also calculated these quantities in the distorted wave Born approximation (DWBA) and the plane wave Born approximation (PWBA). There is good agreement between experiment and the present DWBA and PWBA values for the alignment A20 whereas earlier DWBA values by Pangantiwar and Srivastava (1987) deviate systematically from experiment for E0 < 100 eV. For the ratio of cross sections R0 the present DWBA values agree only qualitatively with the experiment for E0 < 100 eV.
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