PHOTODEGRADATION OF ASTROPHYSICAL ICES INDUCED BY SYNCHROTRON RADIATION
F.A. RIBEIRO1*, G. C. ALMEIDA1, E.F. MENDOZA2, T. MONFREDINI2, S. PILLING3, D.P.P. ANDRADE3, H.M. BOECHAT-ROBERTY2 AND M.L.M. ROCCO1
1Universidade Federal do Rio de Janeiro, Instituto de Química
2Universidade Federal do Rio de Janeiro, Observatório do Valongo
3Universidade do Vale do Paraíba – Instituto de Pesquisa e Desenvolvimento (IP&D)
Acetonitrile (CH3CN), formamide (HCONH2) and acetone (CH3COCH3) are relevant pre-biotic molecules. All these molecules have been identified by their radiofrequency emission toward Sagitarius B2 molecular cloud, a chemically rich region of gas and dust in the vicinities of the Milky Way core. Acetonitrile was also detected in the Kohoutek comet, as well as formamide was found to be present in Hale-Bopp comet and tentatively identified in young stellar objects, such as W33A and NGC 7538 IRS9. All these environments are exposed to ionizing agents, in particular photons, electrons and cosmic rays, causing fragmentation and further desorption of neutral and ionic species, leading to the formation of more complex molecules. In order to simulate the astrophysical reality under laboratory conditions, astrophysical ice analogs of acetonitrile, formamide and acetone were condensed at 10 K in situ inside and ultra-high vacuum chamber. These ices were exposed to zero order synchrotron radiation (non-monochromatic) in the Spherical Grating Monochromator beamline (SGM) of the Laboratório Nacional de Luz Síncrotron (LNLS). The ice degradation was monitored by Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy at the nitrogen and oxygen K-edge. Destruction cross-sections were derived for each molecule as a function of the photon fluence.
Financial Support: LNLS, CNPq, CAPES and FAPERJ; Area: Chemistry;
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