[Diffraction cohérente des rayons X en physique du métal]
En conditions de diffraction cohérente des rayons X, on observe les interférences entre les ondes diffractées par lʼéchantillon. Cela conduit à lʼobservation de tavelures là où une expérience classique donne une intensité diffuse ou une raie de Bragg élargie. Les tavelures correspondent à la configuration locale du désordre dans le volume irradié.
Dans cet article, après une brève description des techniques mises en oeuvre pour observer des tavelures dans une expérience de rayons X, quelques exemples dʼobservation de leur dynamique temporelle sont donnés. On discutera dʼabord le cas de fluctuations réversibles et ensuite de lʼutilisation de cette technique pour étudier la dynamique irréversible de la décomposition dʼalliages à démixtion ou à mise en ordre. On décrira quelque sepériences dʼimagerie des défauts et on discutera des voies ouvertes par lʼapparition des lasers à électrons libres.
In a coherent x-ray scattering experiment, interference of the waves diffracted across the sample is observed. This gives a speckle pattern in the observed scattering intensity, whereas a standard experiment leads to diffuse intensity or to broadening of a Bragg peak. Speckles correspond to the disorder configuration of the irradiated volume and their dynamics provide microscopic information of the time evolution of the sample microstructure.
After a brief description of the techniques used for the observation of speckles in an x-ray experiment, some examples of measured time dynamics are given. These concern reversible fluctuations and irreversible decomposition of unmixing or ordering alloys. A few experiments in defect imaging are described and the studies opened by free electron lasers are briefly discussed.
Mot clés : Diffraction cohérente, Spectroscopie de correlation des photons X, Dynamique des fluctuations
@article{CRPHYS_2012__13_3_227_0,
author = {Fr\'ed\'eric Livet and Mark Sutton},
title = {X-ray coherent scattering in metal physics},
journal = {Comptes Rendus. Physique},
pages = {227--236},
publisher = {Elsevier},
volume = {13},
number = {3},
year = {2012},
doi = {10.1016/j.crhy.2011.11.009},
language = {en},
}
Frédéric Livet; Mark Sutton. X-ray coherent scattering in metal physics. Comptes Rendus. Physique, Volume 13 (2012) no. 3, pp. 227-236. doi : 10.1016/j.crhy.2011.11.009. https://comptes-rendus.academie-sciences.fr/physique/articles/10.1016/j.crhy.2011.11.009/
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