Orbital interpretations of carbonyl shake-up spectra

Non-empirical calculations of carbon and oxygen core-electron shake-up spectra have been performed for a series of carbonyl containing hydrocarbon molecules. An orbital interpretation is surprisingly successful in reproducing the salient as well as many of the detailed features of the spectra. Energy positions and intensities of the C-1s and O-1s spectra show rapidly converging and simplifying trends with respect to the size of the hydrocarbon chain. In the long chain limit only one compound internal carbonyl- and one charge transfer pi-pi* band is predicted in the oxygen case, while two spin-split internal carbonyl bands are predicted for the carbon spectra.