Ultraviolet irradiation of naphthalene in H2O ice:: Implications for meteorites and biogenesis

The polycyclic aromatic hydrocarbon (PAH) naphthalene was exposed to ultraviolet radiation in H(2)O ice under astrophysical conditions, and the products were analyzed using infrared spectroscopy and high-performance liquid chromatography. As we found in our earlier studies on the photoprocessing of coronene in H(2)O ice, aromatic alcohols and ketones (quinones) were formed. The regiochemistry of the reactions is described and leads to specific predictions of the relative abundances of various oxidized naphthalenes that should exist in meteorites if interstellar ice photochemistry influenced their aromatic inventory. Since oxidized PAHs are present in carbon-rich meteorites and interplanetary dust particles (IDPs), and ubiquitous in and fundamental to biochemistry, the delivery of such extraterrestrial molecules to the early Earth may have played a role in the origin and evolution of life.