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Theses

L'émission gazeuse des polymères aliphatiques sous irradiation : effet du pouvoir d'arrêt électronique

Abstract : This thesis contributes to a better understanding of the damaging processes, which occur in polymers under swift heavy ion irradiation. The present study is exclusively devoted to the influence of the electronic stopping power, (dE/dx)e, on the molecular emission under irradiation. The irradiated polymers are polyethylene, polypropylene and polybutene. The (dE/dx)e of the projectiles used varies from 3.5´10-3 MeV.mg-1.cm2 (electron) to 39 MeV.mg?1.cm2 (58Ni). We used two different experimental approaches in order to identify the nature of the emitted gases : mass spectrometry and infrared spectroscopy. The first technique is non selective, therefore, we could detect the emission of H2 and heavy molecules ; it also gives information on the diffusion kinetics of the molecules formed. The use of infrared spectroscopy for this kind of analysis is new and the technique was developed at the laboratory. It enables us to identify, without any ambiguity, molecules with up to three carbon atoms. The experimental spectra are analysed by using reference spectra of pure gases, measured in our laboratory. We have quantified precisely each identified gas, and we have followed the evolution of the radiochemical yields with increasing (dE/dx)e. The results, obtained at different (dE/dx)e, inform us on the different mechanisms of gas molecules formation, for example the side group departure and, at high (dE/dx)e, the fragmentation of the main chain which is due to multiple ionisation of the macromolecule.
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https://tel.archives-ouvertes.fr/tel-00003432
Contributor : Emmanuel Balanzat <>
Submitted on : Monday, September 29, 2003 - 4:32:39 PM
Last modification on : Friday, March 5, 2021 - 3:04:41 PM
Long-term archiving on: : Friday, April 2, 2010 - 7:06:23 PM

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  • HAL Id : tel-00003432, version 1

Citation

Virginie Picq. L'émission gazeuse des polymères aliphatiques sous irradiation : effet du pouvoir d'arrêt électronique. Physique [physics]. Université de Caen, 2000. Français. ⟨tel-00003432⟩

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