Infrared spectra of isolated protonated polycyclic aromatic hydrocarbons:: Protonated naphthalene

(Figure Presented) Fingerprinting: The IR spectrum of protonated naphthalene, the smallest member of the class of protonated polycyclic aromatic hydrocarbons (PAHs), has identified the Ca atom as the preferred protonation site of the isolated molecule (see the figure; IRMPD: infrared multiple-photon dissociation). Significant devia-tions from the corresponding IR spectrum of protonated benzene demonstrate the large impact of additional aromatic rings on the IR fingerprint of protonated PAHs. © 2007 Wiley-VCH Verlag GmbH & Co. KGaA.