Photoelectron spectra and valence shell electronic structure of zinc and cadmium difluoride

Abstract

The He(I)α and He(II)α photoelectron spectra of zinc and cadmium difluoride have been recorded in the vapour phase using a pseudo-molecular beam technique. The spectra were interpreted with the aid of ab initio SCF m.o. calculations on ZnF2. Two different basis sets were used in the calculations and ionization potentials were predicted by both Koopmans' theorem and the ΔSCF method. The electronic structure of the Group IIB difluorides studied was found to be similar to that of the heavier halides except that the ligand-localized m.o.s. appear to have the order σgπuσuπg rather than σgσuπuπg as in the heavier halides. A comparison of the valence electronic structure of the Group IIA and IIB dihalides was made. The d-shell metal-localized ionizations of the Group IIB difluorides studied were observed to be core-like and ligand field effects for the d–1 ionization in the zinc dihalides were considered. In all cases, observations were consistent with largely ionic structures.