Do Atomic Spectra Determine Energy Levels?

(Received 7 December 1994, received in final form 13 April 1995, accepted 18 April 1995)

Abstract
We examine the question of attributing energies to atomic excited states, given experimental line shapes. It is underlined that poles of the resolvant operator are not determined by peaks in cross-sections. Moreover, in the scattering of one photon by an atom, resonance energies seem to depend on final products.