Excitation of K^*(3p⁵4s²²P_3/2,²P_1/2) by electron impact in the range from near threshold to 500 eV: alignment and cross section ratios

Abstract

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.

Fluorescence of polarized atoms excited by polarized electrons

“…2 show that DW alignment parameters of 3 p 5 4s 2 2 P 3=2 state of K excited by electron impact are in good agreement with experimentally determined ones [18] for the energies of the projectile electron larger than 70 eV. For comparison, two cases of calculated data from [18] are presented. DW-6 was obtained by using the optical potential V opt ¼ V st ðrÞ þ V ex ðE; rÞ and the ground state electron density.…”

“…3p 5 4s 2 2 P3=2 transition for K excited by non-polarized electrons. Experimental (squares) and theoretical (DW-6 and DW-7) data are taken from Matterstock et al [18]. Table 1 The asymmetry parameter b of the angular distribution and polarization degree P of linearly polarized radiation following the excitation of Na and K atoms to np 5 ðn þ 1Þs 2 the excitation of non-polarized atoms by non-polarized electrons is presented.…”

“…1 and 2 together with experimental data for Na measured for impact electron energies from the threshold to 80 eV [3] and for K measured in the range of incident electron energy 31.4-500 eV [18], respectively. Theoretical R-matrix and DW method results are also presented for Na [3] and K [18], respectively. For the excitation energies exceeding the threshold twice, the calculated alignment parameters for Na in the 2p 5 3 s 2 2 P 3=2 state (Fig.…”

Heteroepitaxial Growth of 4′-Nitorobenzylidene-3-Acetamino-4-Methoxyaniline on the Single Crystal of 4′-Nitrobenzyliden-3-Ethylcarbonylamino-4-Methoxyaniline

“…the second step of process (1b) and is, in general, dependent on the decay amplitudes of the different ejected autoionizing electron partial waves. However, in the case of (1b) only one autoionizing electron wave is emitted which reduces α 2 to a pure geometrical factor (Cleff and Mehlhorn 1974, Berezhko and Kabachnik 1977, Matterstock et al 1995. For the decay of (1b) we have α 2 = −1.…”

“…An account of the work done so far on this subject has been given by Pangantiwar and Srivastava (1987). Further details can be obtained from the two recent experimental papers from the Freiburg group, Germany (see Matterstock et al 1995, Feuerstein et al 1998. Their measurements are, in fact, the first reliable data on the study of electron impact excitation of the lowest autoionizing levels in K and Na atoms which can be compared directly with the available theoretical cross section results.…”