M. A. MARTIN-DRUMEL, O. PIRALI, Y. LAQUAIS, Institut des Sciences Moléculaires d'Orsay, CNRS, UMR 8214, Université Paris XI, bât. 210, 91405 Orsay Cedex, France; SOLEIL Synchrotron, AILES beamline, L'orme des Merisiers, Saint-Aubin, 91192 Gif-Sur-Yvette, France; C. FALVO, P. PARNEIX AND PH. BRECHIGNAC, Institut des Sciences Moléculaires d'Orsay, CNRS, UMR 8214, Université Paris XI, bât. 210, 91405 Orsay Cedex, France.
%Frequencies and relative intensities of the mid-infrared (MIR) bands of PAHs and PAHs-derivatives (such as PANHs) are similar for this entire class of molecules.
%Nevertheless, little experimental gas phase spectroscopic information is available on the low-frequency vibrational modes of PAHs derivatives preventing the ability to perform specific observational searches.
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FIR gas phase absorption spectra of nine naphthalene derivatives (azulene, quinoline, isoquinoline, biphenyl, diphenylmethane, bibenzyl, 2-, 3-, and 4-phenyltoluene) have been recorded at medium resolution (0.5 cm-1) using a Fourier transform Bruker IFS125 interferometer located on the AILES beamline of SOLEIL synchrotron. Assignments of these weak vibrational bands were performed using density-functional theory calculations carried out at the harmonic and anharmonic levels (B97-1/6-311G(d,p)). Molecular structure dependence of the FIR spectra is discussed based on the comparative study of several selected FIR modes.