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 2-1aser 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. (C) 2003 Elsevier Science B.V. All rights reserved.