ENERGY LEVELS OF SINGLY-IONIZED ACTINIUM - 227AC II

The low configurations of Ac II are known in both parities from the early analysis by Meggers et al.. (57.3). They have been studied recently (Wyart (unp32)) by the parametric Slater-Condon method which led to a few changes in the theoretical assignments. The studied groups are 6d2+6d7s+7s2+5f2+5f7p and 5f6d+5f7s+6d7p+7s7p respectively. This led to reject the two levels 5f7p 3G5 and 6d5f 3H5 reported in (57.3). From the eighty lines which remained unclassified after Meggers's analysis, four upper levels have been found between 57175 and 64285 cm-1 (unp.32). The thirteen levels of the mixed group 7s7d+7p2+6d8s are expected in this energy range and no label have been given so far to these levels. The first two components of the eigenfunction are given in LS coupling, although for 5f7p, the jj coupling is more appropriate (average purity 98 %).