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Title: The anharmonic quartic force field infrared spectra of three polycyclic aromatic hydrocarbons: Naphthalene, anthracene, and tetracene

Current efforts to characterize and study interstellar polycyclic aromatic hydrocarbons (PAHs) rely heavily on theoretically predicted infrared (IR) spectra. Generally, such studies use the scaled harmonic frequencies for band positions and double harmonic approximation for intensities of species, and then compare these calculated spectra with experimental spectra obtained under matrix isolation conditions. High-resolution gas-phase experimental spectroscopic studies have recently revealed that the double harmonic approximation is not sufficient for reliable spectra prediction. In this paper, we present the anharmonic theoretical spectra of three PAHs: naphthalene, anthracene, and tetracene, computed with a locally modified version of the SPECTRO program using Cartesian derivatives transformed from Gaussian 09 normal coordinate force constants. Proper treatments of Fermi resonances lead to an impressive improvement on the agreement between the observed and theoretical spectra, especially in the C–H stretching region. All major IR absorption features in the full-scale matrix-isolated spectra, the high-temperature gas-phase spectra, and the most recent high-resolution gas-phase spectra obtained under supersonically cooled molecular beam conditions in the CH-stretching region are assigned.
Authors:
; ;  [1] ;  [2] ; ;  [3] ;  [1] ;  [4] ;  [5] ;  [6]
  1. Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands)
  2. SETI Institute, 189 Bernardo Avenue, Suite 100, Mountain View, California 94043 (United States)
  3. University of Amsterdam, Science Park 904, 1098 XH Amsterdam (Netherlands)
  4. (Netherlands)
  5. Radboud University, FELIX Laboratory, Toernooiveld 7, 6525 ED Nijmegen (Netherlands)
  6. NASA Ames Research Center, Moffett Field, California 94035-1000 (United States)
Publication Date:
OSTI Identifier:
22493320
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 143; Journal Issue: 22; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ABSORPTION; ANTHRACENE; COMPARATIVE EVALUATIONS; FERMI RESONANCE; INFRARED SPECTRA; MATRICES; MATRIX ISOLATION; MOLECULAR BEAMS; NAPHTHALENE; POLYCYCLIC AROMATIC HYDROCARBONS; RESOLUTION; TETRACENE