Experimental and computational study of the radiation-induced decomposition of formaldehyde. Implications to cometary nuclei |
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Authors: | Rafael Navarro-González Susana Castillo-Rojas Alicia Negrón-Mendoza |
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Affiliation: | (1) Instituto de Ciencias Nucleares, U.N.A.M., Circuito Exterior, C.U., A. Postal 70-543, 04510 México D.F., México;(2) Present address: Laboratory of Chemical Evolution, Department of Chemistry and Biochemistry, University of Maryland, 20742 College Park, Maryland, USA |
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Abstract: | The radiation-induced decomposition of aqueous solutions of formaldehyde was studied at 298 and 77 K in order to obtain an insight into the possible role of ionizing radiation on cometary chemistry. Aqueous solutions of 1.0 mol dm–3 formaldehyde were exposed to -radiation in the dose range from 0.01 kGy to 1.2 MGy. The radiation chemical yield of decomposition of formaldehyde was determined to be: G(–CH2(OH)2)=26.3±1.2 at 298 K and G0.48 at 77 K.Based on previous estimates of the total dose of ionizing radiation that comets have accumulated over 4.6 billion years, we predict a radiation-induced depletion of formaldehyde as a function of depth in comet nuclei: 100% destruction in the outer layers (0–20 m) and 10% destruction in the interior layers.A Portion of this work was presented at the XXVIII COSPAR Plenary Meeting (MF. 7) held at the Hague, The Netherlands on June 25–26, 1990. |
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