Configuration interaction in the spectrum of Kr II

Abstract
The 4s24p44d+4s24p45s+4s4p6 configurations of Kr II have been investigated theoretically, including configuration-interaction effects. The investigation has been carried out by fitting the observed energy levels to theoretical energy expressions using the least-squares technique. The calculated energy levels show much better agreement with the experimental values than those calculated without configuration interaction. The 4s24p4(1D)4d2S1/2 level is found to interact strongly with the 4s4p6 2S1.2 level, and to a lesser degree with the 4s24p4(1S)5s 2S1/2 level. The energy parameters obtained from the least-squares fit are in agreement with the results of parametrized central-field calculations.