Theoretical study of 2s shell photoionization and subsequent Auger decay in atomic sodium

The 2s inner shell photoionization (PI) of Na and Auger decay of 1[s.sup.2]2s2[p.sup.6]3s state in Na+ were investigated using single-configuration and multiconfiguration (MC) approximation methods. The PI cross sections from MC calculations showed excellent agreement with experimental and previous theoretical values. The configuration interaction between 1[s.sup.2]2s2[p.sup.6]3s and 1[s.sup.2]2s2[p.sup.6]4s states was essential in predicting PI cross sections. Moreover, configuration interaction played a prominent role in determination of the Auger lifetime widths of [Na.sup.+] 1[s.sup.2]2s2[p.sup.6]3s ([sup.1][S.sub.0]) compared with the experiment. Key words: photoionization, Auger decay, lifetime width, configuration interaction, multiconfiguration Dirac-Fork. Utilisant les methodes approximatives a configuration simple et multi- configurations (MC), nous etudions la photoionisation (PI) dans la couche interne 2s du Na et la desintegration Auger de l'etat 1[s.sup.2]2s2[p.sup.6]3s dans le [Na.sup.+]. Les sections efficaces PI obtenues des calculs MC montrent un excellent accord avec les valeurs experimentales et avec d'autres calculs theoriques. L'interaction de configuration entre les etats 1[s.sup.2]2s2[p.sup.6]3s et 1[s.sup.2]2s2[p.sup.6]4s est essentielle pour predire correctement les sections efficaces PI. De plus, l'interaction de configuration joue un role capital dans la determination des largeurs de temps de vie Auger de 1[s.sup.2]2s2[p.sup.6]3s ([sup.1][S.sub.0]) dans une comparaison avec l'experience. [Traduit par la Redaction] Mots-cles: desintegration Auger, photo-ionisation, largeur de temps de vie, interaction de configuration, methode Dirac-Fock multi-configurations.
1. Introduction Photoionzation (PI) cross sections are needed in modeling laboratory and astrophysical plasmas [1]. PI of atomic ions is an important process in determining the ionization balance and abundances [...]