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Transport d'ions hydrogénoïdes rapides dans les solides : mise en évidence de l'écrantage dynamique

Abstract : Study of the transport of projectile excited states allows to test the ion-solid interaction, in particular to probe the response of the medium. Two kinds of phenomenon are involved in ion-solid collisions : the succession of ion-atom binary collisions, and the interaction between the ion and the electric field (“wake field”) induced in the medium. We built up the master equation for the density matrix of the core excited states of a swift heavy ion in a solid, taking both physical processes into account. We studied quantitatively the influence of the parameters involved in the description of the transport. In particular, the wake field is responsible for a coherent mixing of quasi degenerate levels. Experimental manifestation of this mixing bring information on the excited state population and the medium response. Using high resolution X-ray spectroscopy, we observed the evolution of np levels (2 < n < 5) as well as some fine structure (n=3) population of the projectile as a function of the target thickness. We present the full experimental study of the systems Kr35+ sur C and Al (E = 60 MeV/A), where excited states are initially populated by simple excitation. The master equation model reproduces faithfully these experimental results as well as those from precedent studies where excited states are populated by mechanical electron capture (MEC). On one hand, experiment-theory comparison allows access to crucial parameters of the excited states evolution, like the wake field value (around 1e9 V.cm-1) and its spatial variation on the atomic orbital scale. On the other hand, it allows to test initial conditions before the transport, in terms of cross sections and collisionnal coherences (excitation and MEC).
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https://tel.archives-ouvertes.fr/tel-00002358
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Submitted on : Wednesday, February 5, 2003 - 4:05:27 PM
Last modification on : Wednesday, December 9, 2020 - 3:13:12 PM
Long-term archiving on: : Friday, April 2, 2010 - 8:04:24 PM

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  • HAL Id : tel-00002358, version 1

Citation

Claude Fourment. Transport d'ions hydrogénoïdes rapides dans les solides : mise en évidence de l'écrantage dynamique. Physique Atomique [physics.atom-ph]. Université Pierre et Marie Curie - Paris VI, 2000. Français. ⟨tel-00002358⟩

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