Interpretation of photoelectron spectra of hydrocarbons using semi-empirical SCF MO calculations

Abstract

It is possible to attain improved agreement between photoelectron-spectroscopic ionization potentials and theoretical orbital energies simultaneously for all electrons in small hydrocarbons by a suitable parametrization of INDO in its modified form, MINDO. The changed parameters concern mainly the resonance integrals, in which the interaction is treated differently for different situations of overlap. The new procedure will be referred to as SPINDO (Spectroscopic-Potentials-adjusted INDO) or, due to its preliminary status, better as SPINDO/1. The photoelectron spectra of hydrocarbons of different types (allene, cyclopropane, norbornadiene, naphthalene, and styrene) are discussed. The conformation of styrene is determined.