Steric inhibition of resonance studied by molecular photoelectron spectroscopy. Part 2.—Phenylethylenes

Abstract

Some aspects of the HeI photoelectron spectroscopy of substituted phenylethylenes and related molecules are presented. The interpretation of the variation of the photoelectron π ionization energies with substituents allows the separation of steric from electronic effects. Interaction of semi-localised π molecular orbitals incorporated within a Hückel type theory provides a means of estimation of the dihedral angles.