HIGH-RESOLUTION PHOTOELECTRON-SPECTROSCOPY OF CH2F2, CH2CL2 AND CF2CL2 USING SUPERSONIC MOLECULAR-BEAMS

Molecular beam photoelectron spectroscopy using He I radiation (584 Angstrom) 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.