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L'Association Européenne de Cristallographie (ECA) organise depuis 2021 des "webinaires déjeuner". Les groupes d'intérêt spéciaux (SIG) et les groupes d'intérêt général (GIG) de l'ECA organisent à tour de rôle un webinaire adapté à la communauté des cristallographes au sens large. Le 23ième webinaire sera diffusé le jeudi 5 octobre 2023 à 13h:   High-resolution X-ray powder diffraction – Application to the study of CO2 trapping in microporous materials par  Catherine Dejoie  (ESRF, Grenoble). Inscriptions ici.

Following the ESRF upgrade and the reconstruction of the storage ring in 2019, the increased brilliance allows new experiments to be carried out, with improved precision and pushing further the detection limits of subtle structural changes occurring in the materials. High-angular resolution powder diffraction, with well-defined and resolved diffraction peaks, is used generally to obtain high-quality data for complex structure refinements. The ID22 beamline of the ESRF is equipped with a Dectris Eiger2 X 2M-W CdTe pixel detector receiving the X-rays transmitted by the thirteen crystals of a custom-made multi-analyser stage [1]. A great advantage of this arrangement is the axial resolution provided by the 2D detector, which allows the effect of axial divergence, which causes the low-angle asymmetry in the peak shape of powder diffraction patterns, to be removed. A second advantage is that the axial acceptance of the detector can be increased as 2𝜃 increases, up to the 38 mm width of the detector, thus increasing the statistical quality of the high angle data while also improving the angular resolution. ID22 has implemented this approach systematically, as an automatic procedure, into its collection of high-resolution powder diffraction data. A case study developed inhouse in relation to the trapping of CO2 in microporous materials will be presented [2], benefitting from the overall improvement of the high-resolution data quality.

[1] Fitch A. et al., J. Synchrotron Rad. 30, 1003-1012 (2023).
[2] Lill J. et al., J. Phys. Chem. 126, 2214-2225 (2022).


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