Habib, Reinhard has nailed it – no need for a larger discussion as these artifacts are well understood. The late William Parrish published a paper describing these sort of artifacts ages ago (maybe 1950’s?).
Andrew ----------------------------------------------------------------------- Dr. E. Andrew Payzant, FASM Distinguished R&D Staff Member Leader, Materials Engineering Group Neutron Scattering Division Mailing Address: Oak Ridge National Laboratory P.O. Box 2008 Building 8600, MS 6475 Oak Ridge, TN, 37831 Cell: (865) 235-4981 Email: payza...@ornl.gov<mailto:payza...@ornl.gov> https://www.ornl.gov/staff-profile/e-andrew-payzant From: rietveld_l-requ...@ill.fr <rietveld_l-requ...@ill.fr> on behalf of Reinhard Kleeberg <kleeb...@mineral.tu-freiberg.de> Date: Monday, September 4, 2023 at 10:47 AM To: Habib Boughzala <habib.boughz...@ipein.rnu.tn> Cc: rietveld_l-requ...@ill.fr <rietveld_l-requ...@ill.fr>, rietveld_l@ill.fr <rietveld_l@ill.fr> Subject: [EXTERNAL] Re: Step-like basline Habib, obviously your instrument is equipped with a not cooled solid state 1D detector (maybe Bruker Lynxeye?) and a Ni filter what is used for "selective" absorbtion of the Cu K beta radiation. What you see in the pattern is mainly a significant part of the tube emission spectrum, diffracted at the Si 111 plane, and modified by the Ni K absorption edge. The peak at ~ 25.8 ° is the remnant Si 111 diffracting the Cu Kbeta1 wavelength 1.39223 A. The edge is the Ni K absorbtion edge (I don't know the wavelength of the edge exactly, ~ 1.49 A), and the doublet at ~ 28.4 ° is the Si 111 diffracting the Cu K alpha1 and alpha2, 1.54059 and 1.54443 A, respectively. The asymmetric slope of the background on the rigth side of the peak is the unfiltered part of the Bremsstrahlung, their low energy part what is not more cut by the Ni absorbtion. As your wafer is a perfect Si 111 plane you get extreme intensity and < 1 % intensity effects become clearly visible. Maybe you have seen a Si powder pattern what appeared to be "clean", but if you would have measured the powder pattern with better counting statistics, your Si 111 region would look quite similar. Greetings Reinhard Zitat von Habib Boughzala <habib.boughz...@ipein.rnu.tn>: > Dear all, > I would like to send you my witness related to this kind of observation. > I can assure that our Bruker D8 is clean and optimized! > > In many cases of well conditioned thin film (spin coating or > controlled diffusion) material this kind of phenomenon is visible > around the highest reflection, especially when the preferred > orientation is drastically present. > > So, in my opinion, Reinhard and Alan are right, and what is > observed is just like reflections broadening, asymmetry, shifting > ...etc ... and can be related to the material behavior. > Now, what is the physical (crystallographic!) property responsible > of this phenomenon? let's open the floor for a large discussion. > > > Habib -- TU Bergakademie Freiberg Dr. R. Kleeberg Mineralogisches Labor Brennhausgasse 14 D-09596 Freiberg Tel. ++49 (0) 3731-39-3244 Fax. ++49 (0) 3731-39-3129
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