Dear all, I have been following this conversation with a lot of interest over the last few days, I did not know much about the early days of powder diffraction and how profile refinement methods were born and evolved and I have learnt many things. I just want to thank everyone who contributed to the conversation for sharing their stories, viewpoints and experiences.
Best, Marco ________________________________ Da: [email protected] <[email protected]> per conto di Alan Hewat <[email protected]> Inviato: sabato 18 agosto 2018 12:22 A: [email protected] Cc: [email protected] Oggetto: Re: Rietveld > As I get older, I believe less and less in legends (AH) > ...the aristocracy of powder diffractionists is displaced (AleB) I don't believe in aristocracy either :-) After Bill David, Lambert van Eijck and I published Hugo Rietveld's glowing obituary<https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fjournals.iucr.org%2Fj%2Fissues%2F2016%2F04%2F00%2Fes0421%2F&data=02%7C01%7C%7C5f8b089e12274e89097208d604f4b001%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636701846301998770&sdata=hvORMZva8k0zJDlsy3%2BKGIbCvPwEuquMVTEh4yyEyMQ%3D&reserved=0>, I received a rough draft of the vL&S paper<https://eur03.safelinks.protection.outlook.com/?url=http%3A%2F%2Fjournals.iucr.org%2Fa%2Fissues%2F2018%2F02%2F00%2Fib5058%2F&data=02%7C01%7C%7C5f8b089e12274e89097208d604f4b001%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636701846301998770&sdata=wc2FDF7TcotSvx7P1mx9Vf5KhXczQPo2s3GY5TubhnY%3D&reserved=0>, and was frankly shocked. But after finding that others shared those views, I suggested a re-write of the paper to make it (perhaps) less controversial and more historical, supported where possible with evidence from the literature. Still, the paper seemed to address questions I myself had about the legend. 1) How could a young man, educated as a classical crystallographer (Bragg peaks, structure factors, Fourier transforms...) produce the revolutionary idea of simply refining the structure to fit the observed profile ? None of the professional crystallographers I knew accepted that idea - only physicists and chemists who used crystallography as a tool. It was a naive physicist's approach. 2) How could Rietveld (1967) in his first paper not emphasise this revolutionary departure from classical crystallographic techniques ? It was almost as if he didn't consider that refining magnetic moments and atom displacements was real crystallography, just a refinement problem where compromises had to be made to get a required result with an inadequate computer. 3) Why did Rietveld leave science in 1974 if he thought that he had achieved something remarkable ? He had a permanent job at a well funded laboratory and a technique that would eventually revolutionise powder diffraction. Ordinary people like me couldn't even get a job at Cambridge (thanks Mike :-) and had to live with a succession of 3 year contracts in foreign countries. When I first knew Hugo, he was a modest, unassuming man, unlike Loopstra who apparently pushed hard. When he saw that "The response was slight, or, rather, non-existent" perhaps like other crystallographers for 20 years he himself doubted the value of profile refinement. And no I don't think the crystallographic establishment should get to name it. Everyone knows what "profile refinement" means. On Sat, 18 Aug 2018 at 11:29, Le Bail Armel <[email protected]<mailto:[email protected]>> wrote: Hi, >As I get older, I believe less and less in legends. In the IUCr 1999 issue >that I cited, I should have also mentioned that there is an interesting >article on p.4 called "The Powder Diffraction >Handicap<https://eur03.safelinks.protection.outlook.com/?url=http%3A%2F%2Fww1.iucr.org%2Fnews%2Fv7n4%2F7-4.pdf&data=02%7C01%7C%7C5f8b089e12274e89097208d604f4b001%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636701846301998770&sdata=69s33ntMgaupjJSK8ktv0pBspV0Q3hrs7%2FzH6KCLDQU%3D&reserved=0>" > by Armel le Bail :-) Indeed, "never say never" is verified again. The powder diffraction handicap (overlapping) can be considered as suppressed by XFEL https://www.xfel.eu/<https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.xfel.eu%2F&data=02%7C01%7C%7C5f8b089e12274e89097208d604f4b001%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636701846301998770&sdata=HEff3HVx0smjSYIlEE7lTYtr95qqa2QbLRN0%2BJVFjpk%3D&reserved=0> where each single microcrystal of the powder produces 3D diffraction data, and all data are recombined ! But for solving too simple problems, you will not have access to that overloaded machine and will have to continue to use your laboratory powder diffractometer and (now) classical approaches. So, once again, the aristocracy of powder diffractionists is displaced, this time from third generation synchrotron to XFEL, amusing, new legends will be built, probably. Best, Armel ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Please do NOT attach files to the whole list <[email protected]> Send commands to <[email protected]<mailto:[email protected]>> eg: HELP as the subject with no body text The Rietveld_L list archive is on http://www.mail-archive.com/[email protected]/<https://eur03.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.mail-archive.com%2Frietveld_l%40ill.fr%2F&data=02%7C01%7C%7C5f8b089e12274e89097208d604f4b001%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636701846301998770&sdata=FtC%2FKA%2FGklrjbBQGcaRquFj5H1UXbLaAidj1WmcxIAM%3D&reserved=0> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -- ______________________________________________ Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE <[email protected]> +33.476.98.41.68 http://www.NeutronOptics.com/hewat<https://eur03.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.NeutronOptics.com%2Fhewat&data=02%7C01%7C%7C5f8b089e12274e89097208d604f4b001%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636701846301998770&sdata=lRf4Ta0H4SxzDGmpKSW2ci8M7XoDVEVSHMiGQ%2BXycTo%3D&reserved=0> ______________________________________________
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Please do NOT attach files to the whole list <[email protected]> Send commands to <[email protected]> eg: HELP as the subject with no body text The Rietveld_L list archive is on http://www.mail-archive.com/[email protected]/ ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
