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arXiv · 1407.2010

Polycyclic Aromatic Hydrocarbons with armchair edges and the 12.7 μm band

A. Candian·P. J. Sarre·A. G. G. M. Tielens
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Abstract

In this Letter we report the results of density functional theory calculations on medium-sized neutral Polycyclic Aromatic Hydrocarbon (PAH) molecules with armchair edges. These PAH molecules possess strong C-H stretching and bending modes around 3 μm and in the fingerprint region (10-15 μm), and also strong ring deformation modes around 12.7 μm. Perusal of the entries in the NASA Ames PAHs Database shows that ring deformation modes of PAHs are common - although generally weak. We then propose that armchair PAHs with NC >65 are responsible for the 12.7 μm Aromatic Infrared Band in HII regions and discuss astrophysical implications in the context of the PAH life-cycle.

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A. Candian, P. J. Sarre, A. G. G. M. Tielens. 2014-10-08. Polycyclic Aromatic Hydrocarbons with armchair edges and the 12.7 μm band. https://doi.org/10.1088/2041-8205%2F791%2F1%2Fl10

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