Doubly excited quartet states in Be II

Abstract
The doubly excited quartet spectrum of Be II, produced by foil excitation of fast Be+ ion beams, has been studied in the wavelength region 600-5000 AA. On the basis of new wavelength determinations for the quartet transitions it has been possible to identify the lower lying, doubly excited levels 1s2snd 4D(n=3-5), 1s2pnd 4D degrees (n=3-5), 1s2p3p 4S, 4P and 4D, and 1s2s4p 4P degrees besides obtaining further evidence for the identification of the 1s2s4s 4S and 1s2s3p 4P degrees levels recently proposed by Mannervik et al. (1981). Recent theoretical calculations support the present identifications.