We report the first observation of infrared emission from a gaseous ionic polycyclic aromatic hydrocarbon (PAH), the pyrene cation, over the range of wavelengths spanned by the ubiquitous interstellar unidentified infrared emission bands (UIRs). The complete set of pyrene cation IR emissions is observed, with relative intensities consistent with astrophysical observations, supporting the propos...

We describe the design and performance of an electron-impact ion beam reflectron system coupled to our ‘‘single-photon infrared emission spectrometer’’ for measurement of infrared emission from excited gas-phase polycyclic aromatic hydrocarbon ~PAH! cations. This experiment provides for direct comparison of laboratory infrared emission spectra of gaseous ionized PAHs with the ‘‘unidentified inf...