Resonance enhanced multiphoton dissociation of polycyclic aromatic hydrocarbons cations in an RF ion trap

We present a novel method for recording the absorption spectra of cations of non-volatile molecules using resonance enhanced multiphoton dissociation of trapped ions. Ions are produced through a 2-laser desorption/ionization process in an RF ion trap mass-spectrometer. A third tunable visible laser induces fragmentation of the trapped ions with a yield dependent on the absorption cross-sections of the ions. Using this method we have recorded the visible absorption spectrum of two PAH isomers, phenanthrene and anthracene.