SIMBAD references

We describe the measurement of infrared emission from excited gas-phase polycyclic aromatic hydrocarbons (PAHs) cations by an electron-impact ion beam reflectron system coupled to our ``single-photon infrared emission'' (SPIRE) spectrometer. This experiment provides for direct comparison of laboratory infrared emission spectra of gaseous ionized PAHs with the ``unidentified infrared emission bands'' (UIRs), the origin of which is still debated. We present results for the pyrene cation (C₁₆H₁₀⁺) and the dehydrogenated pyrene cations (C₁₆H₈⁺ and C₁₆H₆⁺) showing general agreement between the corresponding SPIRE bands and UIR features, although it is not a detailed match. We also discuss possible contributions from the pyrene dimer cation (C₁₆H₁₀)₂⁺.