Interstellar dust polycyclic aromatic hydrocarbons

The polycyclic aromatic hydrocarbons (PAHs) have been inferred to exist in the interstellar dust by the correlation of their general infrared spectral characteristics with observed celestial infrared emission bands [13-15]. 

The study of the effects induced by ion irradiation of solid materials, in particular solid carbons, is relevant in many fields of science and technology. Here we focus on its relevance in astrophysics. Solid carbon-bearing species are extremely abundant in space both in the gas and in the solid phases. A wide variety of solid carbons are observed in the interstellar and circumstellar medium as well as in many objects of the Solar System including those collected at or nearby Earth (interplanetary dust particles and meteorites). Observed and/or predicted carbon-bearing solids (or large molecules) include species with different hybridizations (sp, sp, sp" ) such as amorphous carbons, polycyclic aromatic hydrocarbons, fullerenes, nanodiamonds, graphite, and carbon chain molecules. The literature in the field is enormous interesting reviews can be found in a recent special volume of Speetroehimica Acta [1]. 

X 10 kg. Analyses of interstellar dust clouds and heavenly bodies fotmd on Earth, such as the Murchison meteorite, showed the presence of a variety of important prebiotic compotmds. such as amino acids, ureas, alcohols. aldehydes, purines, polycyclic aromatic hydrocarbons (PAH), and organic acids,"" highlighting the significance of extraterrestrial carbon delivery to Earth. 

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