Experimental study on the interference of autoionizing states of He

The interference of the low-lying doubly excited autoionizing states of helium (2s2(1S),2s2p(3P),2p2(1D) and 2s2p(1P)) is studied. In this paper we concentrate on the interference of the direct and indirect ionization (He+1s-1) in the neighborhood of the critical energy (93.15 eV) of the possible state-to-state interference of the 2s2(1S) and 2p2(1D) resonances. The spectra of autoionizing and scattered electrons measured in three angular ranges at around 87-97 eV primary energy are shown with the computer fitted parameters of the peaks.