title: The anharmonic quartic force field infrared spectra of five non-linear polycyclic aromatic hydrocarbons: Benz[a]anthracene, chrysene, phenanthrene, pyrene, and triphenylene.
abstract: The study of interstellar polycyclic aromatic hydrocarbons (PAHs) relies heavily on theoretically predicted infrared spectra. Most earlier studies use scaled harmonic frequencies for band positions and the double harmonic approximation for intensities. However, recent high-resolution gas-phase experimental spectroscopic studies have shown that the harmonic approximation is not sufficient to reproduce experimental results. In our previous work, we presented the anharmonic theoretical spectra of three linear PAHs, showing the importance of including anharmonicities into the theoretical calculations. In this paper, we continue this work by extending the study to include five non-linear PAHs (benz[a]anthracene, chrysene, phenanthrene, pyrene, and triphenylene), thereby allowing us to make a full assessment of how edge structure, symmetry, and size influence the effects of anharmonicities. The theoretical anharmonic spectra are compared to spectra obtained under matrix isolation low-temperature conditions, low-resolution, high-temperature gas-phase conditions, and high-resolution, low-temperature gas-phase conditions. Overall, excellent agreement is observed between the theoretical and experimental spectra although the experimental spectra show subtle but significant differences.
authors: Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, The Netherlands.
authors: Cameron J
authors: CJ
authors: Mackie
authors: Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, The Netherlands.
authors: Alessandra
authors: A
authors: Candian
authors: SETI Institute, 189 Bernardo Avenue, Suite 100, Mountain View, California 94043, USA.
authors: Xinchuan
authors: X
authors: Huang
authors: University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands.
authors: Elena
authors: E
authors: Maltseva
authors: Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, The Netherlands.
authors: Annemieke
authors: A
authors: Petrignani
authors: Radboud University, Toernooiveld 7, 6525 ED Nijmegen, The Netherlands.
authors: Jos
authors: J
authors: Oomens
authors: NASA Ames Research Center, Moffett Field, California 94035-1000, USA.
authors: Andrew L
authors: AL
authors: Mattioda
authors: University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands.
authors: Wybren Jan
authors: WJ
authors: Buma
authors: NASA Ames Research Center, Moffett Field, California 94035-1000, USA.
authors: Timothy J
authors: TJ
authors: Lee
authors: Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, The Netherlands.
authors: Alexander G G M
authors: AG
authors: Tielens