The high-energy band in the photoelectron spectrum of alkanes and its dependence on molecular structure

In the model for the ionization energies of the C2s-electrons in saturated hydrocarbons, put forward by Heilbronner et al., the energy levels are calculated as eigenvalues of the line graph of the hydrogen-filled molecular graph. It is now shown that in the case of alkanes, these energy levels are related to the Laplacian eigenvalues of the molecular graph. A few rules are formulated, relating these ionization energies with molecular structure.