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Shock-wave processing of C60 in hydrogen

Biennier, L and Jayaram, V and Suas-David, N and Georges, R and Singh, Kiran M and Arunan, E and Kassi, S and Dartois, E and Reddy, K P J (2017) Shock-wave processing of C60 in hydrogen. In: ASTRONOMY & ASTROPHYSICS, 599 .

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Official URL: http://dx.doi.org/10.1051/0004-6361/201629067

Abstract

Context. Interstellar carbonaceous particles and molecules are subject to intense shocks in astrophysical environments. Shocks induce a rapid raise in temperature and density which strongly affects the chemical and physical properties of both the gas and solid phases of the interstellar matter. Aims. The shock-induced thermal processing of C-60 particles in hydrogen has been investigated in the laboratory under controlled conditions up to 3900 K with the help of a material shock-tube. Methods. The solid residues generated by the exposure of a C-60/H-2 mixture to a millisecond shock wave were collected and analyzed using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman micro-spectroscopy, and infrared micro-spectroscopy. The gaseous products were analyzed by Gas Chromatography and Cavity Ring Down Spectroscopy. Results. Volatile end-products appear above reflected shock gas temperatures of 2540 K and reveal the substantial presence of small molecules with one or two C atoms. These observations confirm the role played by the C-2 radical as a major product of C-60 fragmentation and less expectedly highlight the existence of a single C atom loss channel. Molecules with more than two carbon atoms are not observed in the post-shock gas. The analysis of the solid component shows that C-60 particles are rapidly converted into amorphous carbon with a number of aliphatic bridges. Conclusions. The absence of aromatic CH stretches on the IR spectra indicates that H atoms do not link directly to aromatic cycles. The fast thermal processing of C-60 in H-2 over the 800-3400 K temperature range leads to amorphous carbon. The analysis hints at a collapse of the cage with the formation of a few aliphatic connections. A low amount of hydrogen is incorporated into the carbon material. This work extends the range of applications of shock tubes to studies of astrophysical interest.

Item Type: Journal Article
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Additional Information: Copy right for this article belongs to the EDP SCIENCES S A, 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE
Department/Centre: Division of Chemical Sciences > Inorganic & Physical Chemistry
Division of Mechanical Sciences > Aerospace Engineering (Formerly, Aeronautical Engineering)
Date Deposited: 19 May 2017 10:39
Last Modified: 19 May 2017 10:39
URI: http://eprints.iisc.ernet.in/id/eprint/56681

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