Abstract
The interference of a discrete autoionized state with a continuum gives rise to characteristically asymmetric peaks in excitation spectra. The earlier qualitative interpretation of this phenomenon is extended and revised. A theoretical formula is fitted to the shape of the 2s2p1P resonance of He observed in the inelastic scattering of electrons. The fitting determines the parameters of the 2s2p1P resonance as follows: E=60.1 ev, Γ∼0.04 ev, f∼2 to 4×10−3 . The theory is extended to the interaction of one discrete level with two or more continua and of a set of discrete levels with one continuum. The theory can also give the position and intensity shifts produced in a Rydberg series of discrete levels by interaction with a level of another configuration. The connection with the nuclear theory of resonance scattering is indicated.