We have carried out photon irradiation study of naphthalene (C10H8), the smallest polycyclic aromatic hydrocarbon (PAH) in water and ammonia ice mixtures. Photons provided by a synchrotron radiation light source in two broad-band energy ranges in the ultraviolet/near extreme ultraviolet (4-20 eV) and the extreme ultraviolet (13-45 eV) ranges were used for the irradiation of H2O+NH3+C10H8 = 1:1:1 ice mixtures at 15K. We could identify several photo-products, namely CH4, C2H6, C3H8, CO, CO2, HNCO, OCN-, and probably quinoline (C9H7N) and phenanthridine (C13H9N). We found that the light hydrocarbons are preferably produced for the ice mixture subjected to 4-20 eV photons. However, the production yields of CO, CO2, and OCN- species seem to be higher for the mixture subjected to EUV photons (13-45 eV). Therefore, naphthalene and its photo-products appear to be more efficiently destroyed when high energy photons (E > 20 eV) are used. This has important consequences on the photochemical evolution of PAHs in astrophysical environments.
|Title of host publication||Advances in Geosciences|
|Subtitle of host publication||Volume 7: Planetary Science (PS)|
|Publisher||World Scientific Publishing Co.|
|Number of pages||13|
|ISBN (Print)||981270986X, 9789812709868|
|State||Published - 1 Jan 2007|