LOWEST ENERGY VIBRATIONAL MODES OF NINE NAPHTHALENE DERIVATIVES; EXPERIMENT AND THEORY
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Date
2013
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Ohio State University
Abstract
Polycyclic aromatic hydrocarbons (PAHs) have been of considerable interest since they were hypothesized as possible carriers for the unidentified infrared bands (UIBs, also known as aromatic infrared bands, AIBs) observed in a wide variety of astrophysical environments\footnotemark[3]. %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. %In contrast, the fundamental vibrations in the far-infrared (FIR) are particularly interesting since they correspond to skeletal vibrations and are more molecule-specific\footnotemark[4]. Furthermore, with the Herschel, SOFIA and ALMA astronomical facilities, a renewed attention has been given to the FIR spectral region. %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. %\footnotetext[3]{A.~Leger and J.~L.~Puget, \textit{Astron. Astrophys.} 137, L5 (1984); L.~J.~Allamandola \textit{et al.}, \textit{Astrophys. J.} 290 L25 (1985)} %\footnotetext[4]{O.~Pirali \textit{et al.}, \textit{Phys. Chem. Chem. Phys.} 11, 3443 (2009)} %\vspace{1em} \\begin{wrapfigure}[12]{r}{3.5in} \vspace{-.5cm} \hspace*{-0cm} %\includegraphics[width=7cm]{Fig} \epsfig{file=Fig-new.eps,height=1.62in,width=3.5in} \\end{wrapfigure} 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 \wn) 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.
Description
Present address: LPCA, EA 4493, Universite Du Littoral Cote d'Opale, 59140 Dunkerque, France. Present address: CEA, Iramis, Spam, Lab. Francis Perrin, 91192 Gif-sur-Yvette, France
Author Institution: Institut des Sciences Moleculaires d'Orsay, CNRS, UMR 8214, Universite Paris XI, bat. 210, 91405 Orsay Cedex, France; SOLEIL Synchrotron, AILES beamline, L'orme des Merisiers, Saint-Aubin, 91192 Gif-Sur-Yvette, France; Institut des Sciences Moleculaires d'Orsay, CNRS, UMR 8214, Universite Paris XI, bat. 210, 91405 Orsay Cedex, France.
Author Institution: Institut des Sciences Moleculaires d'Orsay, CNRS, UMR 8214, Universite Paris XI, bat. 210, 91405 Orsay Cedex, France; SOLEIL Synchrotron, AILES beamline, L'orme des Merisiers, Saint-Aubin, 91192 Gif-Sur-Yvette, France; Institut des Sciences Moleculaires d'Orsay, CNRS, UMR 8214, Universite Paris XI, bat. 210, 91405 Orsay Cedex, France.