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--></style></head><body lang=EN-US link="#0563C1" vlink="#954F72" style='word-wrap:break-word'><div class=WordSection1><p class=MsoNormal><span style='font-family:"Arial",sans-serif;color:black'>Dear GSAS-II users,</span><o:p></o:p></p><p class=elementtoproof style='margin-bottom:8.0pt'><span style='font-family:"Arial",sans-serif;color:black'> </span></p><p class=elementtoproof style='margin-bottom:8.0pt'><span style='font-family:"Arial",sans-serif;color:black'>I am currently analyzing TOF data, at 300 K, of the Li<sub>x</sub>(C<sub>5</sub>D<sub>5</sub>N)<sub>y</sub>Fe<sub>2</sub>Se<sub>2 </sub>superconductor, measured at the GEM facility of ISIS.</span></p><p style='margin-bottom:8.0pt'><span style='font-family:"Arial",sans-serif;color:black'>I've encountered some issues with the LeBail fitting: </span></p><ol style='margin-top:0in' start=1 type=1><li class=elementtoproof style='margin-bottom:8.0pt;mso-list:l2 level1 lfo1'><span style='font-family:"Arial",sans-serif;color:black'>I've started a LeBail refinement, using a .cif file (I4/mmm) </span><span style='font-family:"Arial",sans-serif;color:black'>derived from a previous Rietveld analysis of the same material. The calculated fit is mostly a line somehow following parallel the background function. The fit also includes at different regions (underneath peaks, or not) some wave-like features of negligible intensity. This fit is particularly observed at the first two Banks. At higher Banks, the fit also displays some sawtoothlike features that don’t match the shape of the observed peaks and are still characterized by low intensity. I am wondering why the LeBail fit doesn't even account for the peaks corresponding to the unit cell of the structure. (Note: I've already verified that the peaks at the low-Q region correspond to our material, and no significant shifts were observed). I've tried also to increase the value of the histogram scale factor, but it didn’t work either. </span></li></ol><ol style='margin-top:0in' start=2 type=1><li class=elementtoproof style='color:black;margin-bottom:8.0pt;mso-list:l0 level1 lfo2'><span style='font-family:"Arial",sans-serif'>Also, when attempting to create a simulated pattern of the same phase </span><span style='font-family:"Arial",sans-serif'>(I4/mmm) using the .prm file provided by GEM, it does not work. It displayed some sharp squeezed peaks of high intensity in the very low-Q, region that don’t correspond to the unit cell provided. However, when applying to the same phase a .prm file from a synchrotron X-ray source produces the expected simulated pattern. <o:p></o:p></span></li></ol><ol style='margin-top:0in' start=3 type=1><li class=elementtoproof style='margin-bottom:8.0pt;mso-list:l1 level1 lfo3'><span style='font-family:"Arial",sans-serif;color:black'>Also I’ve tried to use the prm file provided by GSAS-II, namely the generic TOF (corresponding to a specific flight path and 2theta), but still, I cannot get a fit in the respective Bank of my data, only a weird linear line again.</span></li><li class=elementtoproof style='margin-bottom:8.0pt;mso-list:l1 level1 lfo3'><span style='font-family:"Arial",sans-serif;color:black'>On the other hand, when I tried to fit some older TOF-data, <span style='background:white'>measured </span></span><span style='font-family:"Arial",sans-serif;color:black;background:white'>at NOMAD (NOMAD .prm file used), for the parent material FeSe, the Lebail refinement worked well. </span></li></ol><p class=elementtoproof style='margin-bottom:8.0pt'><span style='font-family:"Arial",sans-serif;color:black;background:white'><o:p> </o:p></span></p><p class=elementtoproof style='margin-bottom:8.0pt'><span style='font-family:"Arial",sans-serif;color:black'>I'm wondering if the issue might be linked to the instrument file parameters or to another fundamental parameter that I haven't yet considered. Or maybe to a characteristic of the measured sample (e.g. nature/evolution/total mass)? Do you have any suggestions on how to address this problem with the GEM data in order to understand the source of the problem?</span></p><p style='margin-bottom:8.0pt'><span style='font-family:"Arial",sans-serif;color:black'>Which parameters should I focus on modifying/refining to attain a LeBail/Rietveld refinement?</span></p><p class=elementtoproof style='margin-bottom:8.0pt'><span style='font-family:"Arial",sans-serif;color:black'>Thank you for your time,</span></p><div><p class=MsoNormal><span style='font-family:"Arial",sans-serif;color:black;background:white'>Best regards,</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-family:"Arial",sans-serif;color:black;background:white'>KAITATZI Myrsini</span><span style='font-family:"Arial",sans-serif;color:black'><br><span style='background:white'>----------------------------------------------------------</span><br><span style='background:white'>PhD Candidate,</span><br><span style='background:white'>Institute of Electronic Structure and Laser (IESL),</span><br><span style='background:white'>Foundation for Research and Technology - Hellas (FORTH),</span><br><span style='background:white'>100 Nikolaou Plastira str, Vassilika Vouton,</span><br><span style='background:white'>700 13 Heraklion, Crete,</span><br><span style='background:white'>GREECE</span><br><br><span style='background:white'>Office Phone (+30) 2810 391874</span></span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-family:"Arial",sans-serif;color:black;background:white'>Lab Phone (+30) 2810 391349</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-family:"Arial",sans-serif;color:black'><br></span><span style='font-family:"Arial",sans-serif;color:blue;background:white'><a href="https://www.iesl.forth.gr/en/research/magnetic-materials">Quantum Materials & Magnetism Lab</a></span><o:p></o:p></p></div><p class=MsoNormal><span style='font-family:"Arial",sans-serif;color:black;background:white'>----------------------------------------------------------</span><o:p></o:p></p><p class=MsoNormal><span class=DefaultFontHxMailStyle><o:p> </o:p></span></p><p class=MsoNormal><span class=DefaultFontHxMailStyle><o:p> </o:p></span></p><p class=MsoNormal><span class=DefaultFontHxMailStyle><o:p> </o:p></span></p></div></body></html>