Inter-subshell correlations and two-electron detachment in the 4d spectrum of In I

Abstract

The absorption spectrum of In I between 320 and 1000 Å has been recorded for the first time. Over 100 new transitions have been observed, of which the most intense can be ascribed to excitation from the 4d subshell. Numerous series due to simultaneous excitation of two electrons from the 5s 2 5p subconfiguration are also detected in the vicinity of the more intense 4d → p transitions. Intensity peculiarities suggest that the two-electron series arise through inter-subshell correlations. ‘Quenching’ of the series due to excitation of one electron from the 4d subshell is observed as the threshold for detachment of two electrons is approached.