Soft X-ray emission spectroscopy of polycyclic aromatic hydrocarbons

High-resolution CK X-ray emission spectra of polycyclic aromatic hydrocarbons (PAH) were measured using synchrotron radiation. The main peak energies in the PAH X-ray spectra shifted to a higher energy region as the ratio of hydrogenated outer carbon atoms to the non-hydrogenated inner carbon atoms increased. Discrete variational (DV)-Xalpha molecular orbital calculations provided theoretical confirmation that the spectral features depend on the ratio of hydrogenated/non-hydrogenated carbon atoms, which suggests that the features around the main peaks provide the information of the degree of hydrogenation in PAH compounds. (C) 2004 Elsevier B.V. All rights reserved.