Radiative cascades from doubly excited He states - art. no. 040501

Resonance profiles of spectroscopically resolved radiative transitions from (2pnd)P-1(o), (sp,2n +)P-1(o), and (sp,2n -)P-1(o) doubly excited He state s with n = 3,...,7 were investigated. The (2p3d)P-1(o)-(1s3d)D-1(e)-(1s2p)P -1(o)-1s(2) S-1(e) cascade transitions were observed using photon induced f luorescence spectroscopy in the vacuum ultraviolet and the visible spectral range. The (2pnd) levels populate predominantly (1 snd)D-1 levels, while f or the (sp,2n+or-) levels, n(1)S levels are populated as well. The experime nts demonstrate that further quantitave branching ratio measurements are ne eded in order to test matrix elements for radiative transitions from He**.