Extraction of accurate autionisation widths from the emission spectrum of doubly-excited He

Abstract

The autoionisation width of the 2s2p 3P0 level in He I has been determined through measurements of the widths of three different optical transitions, namely 2s2p 3P0-2p3p 3Pe, 2s3p 3P0-'2p3p' 3De and 2s2p 3P0-'2p4p' 3De giving the results 7.12+or-0.12, 8.36+or-0.08 and 8.32+or-0.15 meV respectively. As a tentative explanation for the extra broadening of transitions with 3De states as initial states the authors suggest that 3De states but not 3Pe states have an unusually large fine-structure splitting.