Energy variation of double K-shell photoionization of Ne
Résumé
We report on an experimental and theoretical study of double K-shell photoionization of Ne over the 2.3-8.5 keV x-ray energy range. The ratio of double-to-single K-shell photoionization cross sections was determined experimentally by measuring the relative rates of the KK − KL 2,3 L 2,3 (2 D) Auger hypersatellite and the K − L 2,3 L 2,3 (1 D) diagram Auger transitions. By scaling the hypersatellite-diagram Auger-electron ratios to KK/K cross-section ratios, comparison was made with theoretical cross-section ratios of He-like Ne 8+ determined by the R matrix with pseudostates method. The experimental Ne and theoretical Ne 8+ cross-section ratios show similar variations with energy, but the experimental ratios systematically exceed the calculated ratios and also show a lower threshold energy for double K-shell photoionization onset compared to the computed Ne 8+ threshold. The discrepancy is attributed to effects of L-shell electrons not included in the He-like Ne 8+ calculations. Quantified scaling with nuclear charge Z along the He-like isoelectronic sequence indicates that the measured 10-electron Z = 10 double K-shell photoionization cross section behaves like the computed He-like Z = 8.9 cross section, suggesting an effective nuclear screening parameter of s L = 1.1 by the additional eight outer L-shell electrons. Experimental results for the energy variations of Auger electron transitions from other multielectron hole states are also discussed.
Domaines
Physique Atomique [physics.atom-ph]Origine | Fichiers éditeurs autorisés sur une archive ouverte |
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