A situation like you are describing can happen in small molecule and power diffraction. If you explain what you are actually doing, it might be possible to speculate...
Best, BR -----Original Message----- From: CCP4 bulletin board <CCP4BB@JISCMAIL.AC.UK> On Behalf Of Kamil Krawczyk Sent: Tuesday, December 22, 2020 14:27 To: CCP4BB@JISCMAIL.AC.UK Subject: [ccp4bb] Relationship of crystallographic planes and reflections, e.g. (200) and (400) Hi all, As an experimental physicist slowly becoming more acquainted with crystallography, I have a bit of clerical issue visualizing this particular problem in my head: For example, the 400 and 200 reflections in a diffractogram are related to the 100 family of crystallographic planes; I'd imagine, that in real space, the higher order plane (e.g. the 400) corresponds to atoms 'closer' to the center of the crystal/unit cell. I have an interesting observation where I am seeing the 400 peak intensity go down (likely due to increased RMS motion), whereas the 200 reflection does not really change in its intensity. Furthermore, I see a shift in the 200 peak, implying an expansion (a shift to lower q), but no abnormal change in the 400 peak position. What I am having a really hard time wrapping my head around is how these two events can be occurring simultaneously; I would naively say that since the 400 reflection is showing an increased RMS, the 400 peak should likely shift - not the 200. Does anybody have an easy way to visualize this? I am trying to look at crystallographic vectors in VESTA on a model system, but sadly have not been able to see the light just yet. Thank you! And sorry for dropping all the parentheses on reflection names, it saved me some typing :p ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a mailing list hosted by www.jiscmail.ac.uk, terms & conditions are available at https://www.jiscmail.ac.uk/policyandsecurity/ ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a mailing list hosted by www.jiscmail.ac.uk, terms & conditions are available at https://www.jiscmail.ac.uk/policyandsecurity/
