Photoelectron spectra of fluorotribromomethane and fluorotrichloromethane

High resolution He(I) photoelectron spectra are reported for fluorotribromomethane CFBr3 and fluorotrichloromethane CFCl3. The assignments are based on CNDO/2 calculations, symmetry arguments, the fine structures of the bands, and comparison with the photoelectron spectra of related compounds. Linear relationships have been found between the Pauling electronegativity values for the halogen atoms and the observed vertical ionization energies corresponding to a2 of a2′ orbitals of CFX3 and related compounds CHX3, OPX3, BX3 and PX3 (X = F, Cl, Br, I).