High resolution photoelectron spectroscopy of CH₂F₂, CH₂Cl₂ and CF₂Cl₂ using supersonic molecular beams

Abstract

Molecular beam photoelectron spectroscopy using He I radiation (584 Å) has been used to study the electronic structures of CH₂F₂, CH₂Cl₂ and CF₂Cl₂. The spectra obtained at a resolution of 13 meV show a number of new features, in addition to those reported earlier in the literature. Accurate values of the ionization potentials were obtained, and many new vibrational progressions were resolved and assigned. The first four ionic states are discussed in more detail on the basis of reported configuration interaction calculations and photoionization measurements. Ambiguities regarding the ordering of these states have been resolved. Although the agreement between theory and experiment is good in CF₂Cl₂, there are significant differences in CH₂F₂ and CH₂Cl₂.