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Valine Radiolysis by H+, He+, N+, and S15+ MeV Ions

Abstract : Radiolysis of biomolecules by fast ions has interest in medical applications and astrobiology. The radiolysis of solid D-valine (0.2-2 µm thick) was performed at room temperature by 1.5 MeV H + , He + , N + , and 230 MeV S 15+ ion beams. The samples were prepared by spraying/dropping valine-water-ethanol solution on ZnSe substrate. Radiolysis was monitored by infrared spectroscopy (FTIR) through the evolution of the intensity of the valine infrared 2900, 1329, 1271, 948, and 716 cm −1 bands as a function of projectile fluence. At the end of sample irradiation, residues (tholins) presenting a brownish color are observed. The dependence of the apparent (sputtering + radiolysis) destruction cross section, σ d , on the beam stopping power in valine is found to follow the power law σ d = aS e n , with n close to 1. Thus, σ d is approximately proportional to the absorbed dose. Destruction rates due to the main galactic cosmic ray species are calculated, yielding a million year half-life for solid valine in space. Data obtained in this work aim a better understanding on the radioresistance of complex organic molecules and formation of radioproducts.
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Contributor : Hermann Rothard <>
Submitted on : Tuesday, December 1, 2020 - 10:30:32 AM
Last modification on : Friday, April 23, 2021 - 3:15:34 AM
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Cíntia A. P. da Costa, Gabriel S. Vignoli Muniz, Philippe Boduch, Hermann Rothard, Enio F. da Silveira. Valine Radiolysis by H+, He+, N+, and S15+ MeV Ions. International Journal of Molecular Sciences, MDPI, 2020, 21 (5), pp.1893. ⟨10.3390/ijms21051893⟩. ⟨hal-03032962⟩



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