An analogue to koopmans' theorem for the problem of vibrational structure in electron detachment spectra

The vibrational structure in electron detachment spectra is calculated using a formalism recently developed. In this formalism only date from the molecule are used; no data of the ion are required. The vibrational structure in the photoelectron (PE) spectrum of H₂O is well reproduced using only the first order one-body coupling constants. Especially the interpretation of the structure of the third band which is not well resolved in the experimental spectrum is clarified.