title: Ultraviolet photostability of adenine on gold and silicon surfaces.
abstract: The adenine molecule is a DNA nucleobase, an essential component of genetic material. Because of the important role of DNA nucleobases in terrestrial biochemistry, we have studied the molecular adsorption, orientation, and chemical binding of adenine on metallic and semiconducting surfaces, such as gold and silicon, respectively, and their stability toward ultraviolet radiation by X-ray photoelectron spectroscopy (XPS) and reflection absorption infrared spectroscopy (RAIRS) techniques. We have exposed the adenine surface system to UV radiation (200-400 nm) under a high-vacuum environment (10(-7) mbar) to study the photostability and photochemistry of adenine on different surfaces. After 10 or 24 hours of exposure under interplanetary space conditions, UV radiation induces desorption and partial dissociation of the molecule, which is dependant on the nature of the surface. The electronic excitations, induced in the material by UV absorption, play a major role in the photodestruction of the absorbed molecules on the solid surfaces.
authors: Centro de Astrobiología (CSIC-INTA), 28850-Torrejón de Ardoz, Madrid, Spain. mateome@inta.es
authors: Eva
authors: E
authors: Mateo-Martí
authors: Claire-Marie
authors: CM
authors: Pradier
authors: Jose-Angel
authors: JA
authors: Martín-Gago
mesh_terms: D000225:Adenine / Q000737:chemistry*; D000327:Adsorption / Q000528:radiation effects; D006046:Gold / Q000737:chemistry*; D007259:Infrared Rays; D012825:Silicon / Q000737:chemistry*; D013057:Spectrum Analysis; D013499:Surface Properties / Q000528:radiation effects; D013816:Thermodynamics; D013997:Time Factors; D014466:Ultraviolet Rays
chemical_list: D006046:Gold; D000225:Adenine; D012825:Silicon