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| Naji, M. |
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| Motta, Antonella |
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| Aletan, Dirar |
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| Mohamed, Tarek |
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| Ertürk, Emre |
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| Taccardi, Nicola |
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| Kononenko, Denys |
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| Petrov, R. H. | Madrid |
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| Alshaaer, Mazen | Brussels |
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| Bih, L. |
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| Casati, R. |
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| Muller, Hermance |
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| Kočí, Jan | Prague |
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| Šuljagić, Marija |
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| Kalteremidou, Kalliopi-Artemi | Brussels |
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| Azam, Siraj |
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| Ospanova, Alyiya |
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| Blanpain, Bart |
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| Ali, M. A. |
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| Popa, V. |
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| Rančić, M. |
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| Ollier, Nadège |
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| Azevedo, Nuno Monteiro |
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| Landes, Michael |
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| Rignanese, Gian-Marco |
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Carrez, Ph.
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Topics
Publications (3/3 displayed)
- 2008Evidence from numerical modelling for 3D spreading of [001] screw dislocations in Mg2SiO4 forsteritecitations
- 2004Laboratory Studies of the Ion-irradiation of Dust Analogs: Application to the Evolution of Interstellar Silicates
- 2001Structural and chemical alteration of crystalline olivine under low energy He<SUP>+</SUP> irradiationcitations
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document
Laboratory Studies of the Ion-irradiation of Dust Analogs: Application to the Evolution of Interstellar Silicates
Abstract
We present the results of experiments aimed at simulating the interaction of silicate grains with atoms ionized and accelerated during the propagation of supernova-generated shock waves. Such an interaction is a potentially important process for the silicate evolution in the diffuse interstellar medium (ISM). Olivine, enstatite and diopside were irradiated with low energy (4-50 keV) H<SUP>+</SUP> and He<SUP>+</SUP> ions with a maximum fluence of 10<SUP>18</SUP> ions/cm<SUP>2</SUP>. The irradiated samples were analyzed by transmission electron microscopy, X-ray photoelectron spectroscopy and infrared micro-spectroscopy, allowing us to study changes in the mineral stoichiometry, structure and spectral characteristics induced by the irradiations. Irradiation of these three minerals leads to their total amorphization for ions fluences ≤ 10<SUP>18</SUP> ions/cm<SUP>2</SUP>. This amorphization is accompanied by the implantation into the target mineral of incident ions which form bubbles and modify the compactness of the mineral. Furthermore at 4 and 10 keV, stoichiometric changes were observed in the studied sample, olivine, which is deficient in oxygen and magnesium after the irradiation. These physico-chemical modifications are translated into important changes of the infrared spectral characteristics of the minerals, which, after the irradiation, consist of two broad and structureless bands at ̃ 9.8 and 18 μm, characteristic of amorphous materials and qualitatively similar with the spectrum of the interstellar medium. Since the experimental conditions used in this study are compatible with the interstellar case, the interaction of grains with ions accelerated in high velocity supernovae-generated shock waves appears to be an important process for the dust evolution and may be responsible for the absence of crystalline silicates in the ISM....