Ion radiation in icy space environments: synthesis and radioresistance of complex organic molecules (Topical Review)
Prudence C.J. Ada Bibang1, Aditya N. Agnihotri1,*, Basile Augé1, Philippe Boduch1, Charles Desfrançois2, Alicja Domaracka1, Frédéric Lecomte2
Bruno Manil2, Rafael Martinez3, Gabriel S.V. Muniz1,**, Nicolas Nieuwjaer2, and Hermann Rothard1
1Centre de Recherche sur les Ions, les Matériaux et la Photonique, Normandie Univ, ENSICAEN, UNICAEN, CEA, CNRS, CIMAP, 14000 Caen, France
2Laboratoire de Physique des Lasers (LPL-UMR CNRS 7538), Université Paris 13 Villetaneuse, France
3Departamento de Física, Universidade Federal do Amapá, Macapa, Brazil
Received January 14, 2019, published online April 26, 2019
Ices are omnipresent in cold regions in space on, e.g., comets, dust grains, transneptunian objects, surfaces of planets and their satellites. The dominant molecule in such ices is water, but also other small molecules or even complex organic molecules (COMs) may be present. Ionizing radiation (UV photons, electrons, ions from cosmic rays or solar wind) induces several physico-chemical processes such as radiolysis. The fragmentation of initial molecules followed by chemical reactions between radicals may lead to formation of new molecules. Furthermore, also implanted projectiles can contribute to chemistry by forming new molecular species. Other observed effects include structural changes (compaction, amorphization) and desorption (sputtering) of particles from the surface. At CIMAP (Caen, France), using the different beam lines of the GANIL facility, and at GSI (Darmstadt, Germany), the interaction of swift highly charged heavy ions with astrophysical ices has been studied in a wide projectile energy range from keV to GeV. Here, two examples of our studies on astrophysical and astrochemical applications will be discussed in detail: 1) the synthesis of COMs under irradiation of ices made of small molecules, and 2) radiosensitivity of COMs such as pyridine, glycine and adenine, both for isolated molecules in the gas phase and in condensed phase. Special emphasis is given on pyri-dine and pyridine in water matrix.