Anharmonicity and the infrared emission spectrum of highly excited PAHs

Abstract

Aims. Infrared (IR) spectroscopy is a powerful tool to study molecules in space. A key issue in such analyses is understanding the effect that temperature and anharmonicity have on different vibrational bands, and thus interpreting the IR spectra for molecules under various conditions. Methods. We combined second order vibrational perturbation theory and the Wang-Landau random walk technique to produce accurate IR spectra of highly excited PAHs. We fully incorporated anharmonic effects, such as resonances, overtones, combination bands, and temperature effects. Results. The results are validated against experimental results for the pyrene molecule (C16H10). In terms of positions, widths, and relative intensities of the vibrational bands, our calculated spectra are in excellent agreement with gas-phase experimental data.

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Cited by in corpus (6)

• Probing computational methodologies in predicting mid-infrared spectra for large polycyclic aromatic hydrocarbons
• Experimental Approach to the Study of Anharmonicity in the Infrared Spectrum of Pyrene from 14 to 723 K
• Orion Bar as a window to the evolution of PAHs
• The infrared bands of polycyclic aromatic hydrocarbons in the 1.6-1.7 μm wavelength region
• Aromatic Species in the Molecular Universe
• Anharmonic infrared spectra of cationic pyrene and superhydrogenated derivatives