| Summary: | Recently there has been considerable interest in studying the interactions of orbitals which were formerly thought of as localized and isolated. The technique of Photoelectron Spectroscopy (PES) is well suited for this and PE spectra are presented here for the series of five membered ring molecules consisting of tetrahydrofuran, γ-butyrolactone, 2,5-dihydrofuran, γ-crotonolactone, 1,3-dioxolane, ethylene carbonate, vinylene carbonate, 4-cyclopentene 1,3-dione, maleimide and maleic anhydride. In these spectra the IP's of the carbonyl oxygen lone pairs and the higher π levels have been assigned and trends in these IP's established in the series. For the carbonyl oxygen lone pair, the shift in IP caused by various groups (oxygen atoms α to the carbonyl, double bonds in the ring and additional carbonyl groups β to the one in question) are found to be approximately additive, which suggests that inductive effects are important. However, the pattern of π IP's must be rationalized in terms of both inductive and resonance effects. Finally some correlations with UV spectra for the last three molecules are presented. === Science, Faculty of === Chemistry, Department of === Graduate
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