Journal of Crystallographic and Spectroscopic Research, Vol. 12, No. 3, 1982 Fine structure of UV photoelectron spectra of cyclic imides D. AJO and M. CASARIN Istituto di Chimica e Tecnologia dei Radioelementi del C.N.R. Corso Stati UnitL 35100 Padova, Italy G. GRANOZZI* and A. POLI Istituto di Chimica Generale ed Inorganica dell'Universith Via Loredan 4, 35100 Padova, Italy and T. PARASASSI Istituto Chimico dell' Universith Citth Universitaria, 00100 Rome, Italy (Received November 26, 1981) Abstract He(I) excited photoelectron spectra of succinimide, maleimide and their N-methyl derivatives are presented and discussed. The spectra are assigned by comparison with related molecules and analysis of the vibrational structure of the photoelectron bands. The effects of N-methyl substitution on both band position and fine structure are described. Introduction A better understanding of the relationships between structure and chemical properties of organic molecules can be gained by studying their electronic structure. /3-dicarbonyl systems have been the object of a wide number of investigations by gas-phase UV photoelectron (PE) spectroscopy, a through-bond interaction mechanism between the oxygen nonbonding (no) orbitals being proposed, leading to the linear combinations n~ and no (Dougherty et al., 1978). There are in the literature few and generally incomplete PE studies on imides. The results reported in the present paper are a part of a systematic 227 0277-8068/82/0600-0227503.00/0 9 1982 Plenum Publishing Corporation