Photoelectron spectra and electronic structure of the dihalides of Mn, Fe, Co and Ni

Abstract

He I/II ultraviolet photoelectron spectra are presented for molecular MnX₂, FeX₂, CoX₂, NiX₂ and MnI₂ where X = F and Br. Using the results of an existing photoelectron study of the chlorides of these metals, analyses of the photoelectron spectra are developed which appear to be consistent for the various possible groups of molecules, i.e. for a given metal with different halogen atoms or for a given halogen with different metal atoms. The proposed analysis is discussed in terms of both the available ab initio molecular-orbital calculations of the energies of the singly ionized molecules and in terms of intensity changes observed between spectra recorded with He Iα and He IIα radiation. These can be related to the metal d parentage of the ionized orbital.