Photoelectron spectra of lodobenzenes

Abstract

The photoelectron spectra of iodobenzene and 1,2-, 1,3-. and 1,4-di-iodobenzene have been recorded by using He^I excitation. The electronic structure of these compounds is discussed in terms of a simple model of interaction between known orbitals of the composite parts, i.e. the molecular orbitals of benzene and the 5p atomic orbitals of iodine, taking their energy and symmetry but no spin–orbit coupling into account. The assignment is simplified by the characteristic shapes of several systems, which holds especially for the lone-pair electrons on iodine. Orbital sequences are given down to ionisation energies of 17 eV. Assignments are supported by comparison with the photoelectron spectra of 1,2,3,4-tetrafluoro-5,6-di-iodo- and 1,2,4,5-tetrafluoro-3,6-di-iodo-benzene.