Radiolysis of astrophysical ices by heavy ion irradiation: destruction cross section measurement

• Published in: Физика низких температур
• Date: 2012
• Main Authors: de Barros, A.L.F., Boduch, P., Domaracka, A., Rothard, H., da Silveira, E.F.
• Format: Article
• Language: English
• Published: Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України 2012
• Subjects: Low Temperature Spectroscopy and Radiation Effects
• Online Access: https://nasplib.isofts.kiev.ua/handle/123456789/117431
• Journal Title: Digital Library of Periodicals of National Academy of Sciences of Ukraine
• Cite this: Radiolysis of astrophysical ices by heavy ion irradiation:
 destruction cross section measurement / A.L.F. de Barros, P. Boduch, A. Domaracka, H. Rothard, E.F. da Silveira // Физика низких температур. — 2012. — Т. 38, № 8. — С. 953-960. — Бібліогр.: 44 назв. — англ.

Many solar system objects, such as planets and their satellites, dust grains in rings, and comets, are known to
 either be made of ices or to have icy surfaces. These ices are exposed to ionizing radiation including keV, MeV
 and GeV ions from solar wind or cosmic rays. Moreover, icy dust grains are present in interstellar space and
 in particular in dense molecular clouds. Radiation effects include radiolysis (the destruction of molecules leading
 to formation of radicals), the formation of new molecules following radiolysis, the desorption or sputtering of
 atoms or molecules from the surface, compaction of porous ices, and phase changes. This review discusses the
 application of infrared spectroscopy FTIR to study the evolution of the chemical composition of ices containing
 the most abundant molecular species found in the solar system and interstellar medium, such as H₂O, CO, CO₂
 and hydrocarbons. We focus on the evolution of chemical composition with ion fluence in order to deduce the
 corresponding destruction and formation cross sections. Although initial approach focused on product identification,
 it became increasingly necessary to work toward a comprehensive understanding of ice chemistry. The
 abundances of these molecules in different phases of ice mantles provide important clues to the chemical processes
 in dense interstellar clouds, and therefore it is of importance to accurately measure the quantities such as
 dissociation and formation cross sections of the infrared features of these molecules. We also are able to obtain
 the scaling of these cross sections with deposited energy.