Optical Properties of Polycyclic Aromatic Hydrocarbons

'In a pair of articles that appeared recently in The Astrophysical Journal (Vol 629, 1183-1187 and 1188-1210) Astrochem lab scientists Mattioda, Allamandola, and Hudgins presented the largest collection anywhere of near-IR (lab) spectra of ionized PAHs and a model that explains why even in areas of low UV flux astronomers have observed mid-IR emission from PAH ions. The answer: absorption in the NIR'

Comparison of the Li & Draine (2002) model (green line) with the experimental average NIR cross section (black line) for the PAH ions measured by MHA05. This comparison shows that ionized PAHs absorb with substantial strength at significantly longer wavelengths than predicted for the modeled generic 'astronomical PAHs.' Also shown are the NIR model spectra described by eqs. (5) (blue line) and (6) (red line) in the text. The asterisk denotes an artifact introduced by the spectrometer¹s beam splitter.

Mattioda, A. L.; Allamandola, L. J.; Hudgins, D. M. (2005) The Ultraviolet to Near-Infrared Optical Properties of Polycyclic Aromatic Hydrocarbons: A Semiempirical Model. [PDF]


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