Plasmon excitation in polycyclic aromatic hydrocarbons studied by photoionization

The photoionization efficiency curves of phenanthrene, anthracene, fluoranthene, pyrene and triphenylene have been measured by VUV photoionization. All spectra show a similar resonance peak at around 17 eV. This phenomenon can be explained as being due to autoionization via a giant plasmon resonance. Autoionization has a negligible contribution to fragmentation processes which occur in the same energy range.