Correlation effects in fluorescence decay of doubly excited states in helium

According to the recent calculations the fluorescence lifetimes of low-lying doubly excited states in helium below the second ionization threshold converge to series specific value generally larger than the fluorescence lifetime of 2p → 1 s transition in He+. To study this phenomena we generated various probability densities from the correlated doubly excited state wavefunctions. The different fluorescence rates may be clearly associated to the behavior of the unconditional probability density of a single electron close to the nucleus. The degeneracy is destroyed by the Stark effect occurring in the body-frame when the outer electron polarizes the inner one into specific linear combination of 2s and 2p orbitals. (author)