Photoelectron spectra and orbital assignments by sum rule consideration: Ethyl and n-propyl fluorides

The He I photoelectron (PE) spectra of C₂H₅F and n-C₃H₇F have been obtained. The PE spectra indicate that the first ionization potentials are about 0.4 eV higher than those of the parent alkanes owing to the inductive effect of fluorine. All the PE bands obtained here have been interpreted in terms of appropriate p-type localized MO's using the sum rule described previously by the authors. Orbital energy diagrams involving the inductive effect of fluorine are illustrated. The semi-empirical CNDO/2 and MINDO/2 methods were also employed to help confirm the present orbital assignments.