title: Single and double photoionizations of methanal (formaldehyde).
abstract: Single and double photoionization spectra of formaldehyde have been measured at 40.81 and 48.37 eV photon energy and the spectrum of the doubly charged cation has been interpreted using high-level electronic structure calculations. The adiabatic double-ionization energy is determined as 31.7+/-0.25 eV and the vertical ionization energy is 33 eV. The five lowest excited electronic states are identified and located. The potential-energy surfaces of the accessible states explain the lack of stable H2CO2+ dications and the lack of vibrational structure. The experimental double-ionization spectrum can be decomposed into two distinct contributions, one from direct photoionization and the second from indirect double photoionization by an inner-valence shell Auger effect.
authors.affiliation: Theoretical Chemistry Group, University of Marne-la-Vallée, Champs sur Marne, F-77454 Marne-la-Vallée, Cedex 2, France. hochlaf@univ-mlv.fr
authors.forename: M
authors.initials: M
authors.lastname: Hochlaf
authors.forename: J H D
authors.initials: JH
authors.lastname: Eland