May he rest in peace. He did a great job for all the crystallographers.

Fabrizio Guzzetta
Ph.D. student, Dept. Quimica Inorganica y Organica, UJI
Castellon de la Plana
Spain

2016-07-19 14:57 GMT+02:00 Alan Hewat <alan.he...@neutronoptics.com>:

> *The passing of Hugo Rietveld, on the 50th anniversary of Rietveld
> Refinement and the 100th anniversary of Powder Diffraction*
>
> It is our sad duty to report the death of Hugo Rietveld at the age of 84
> after a short illness. He leaves behind his wife, a son and two daughters
> to whom we extend our heartfelt sympathy on behalf of the more than one
> thousand members of the Rietveld Mailing List.
>
> Hugo was born on the 7 March 1932 in The Hague and migrated to Western
> Australia with his family, where in 1957 he enrolled at the University of
> WA at the same time as Brian O’Connor and Syd Hall.  He obtained his Ph.D.
> under the supervision of Ted Maslen who had studied under Dorothy Hodgkin
> at Oxford. Hugo pioneered single crystal neutron diffraction at Lucas
> Heights Sydney with Terry Sabine, and their first paper was published in
> Nature in 1961.
>
> Clews C J B, Maslen E N, Rietveld H M and Sabine T M (1961) Nature 192 154
> <http://www.nature.com/nature/journal/v192/n4798/abs/192154a0.html>
> “X-Ray and Neutron Diffraction Examination of p-Diphenylbenzene"
>
> Hugo's experience with manual data collection and refinement convinced him
> of the need to computerise such tasks, and at Lucas Heights and the UWA he
> programmed two of the first IBM-1620 mainframes
> <http://www-03.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP1620.html> 
> in
> Fortran-II. After obtaining his Ph.D. in 1964 with Dorothy Hodgkin as
> external examiner, (she had received the Nobel Prize for her work on
> penicillin and vitamin B12), he joined the neutron diffraction group of the
> Reactor Centrum Nederland in Petten and his interest turned to powder
> diffraction because large single crystals were not available for the
> inorganic materials of interest.
>
> The young group at Petten including Bert Loopstra, Bob van Laar and Hugo
> Rietveld first addressed the problem of overlapping powder reflections by
> using a relatively long neutron wavelength (2.6 Å) with a pyrolytic
> graphite filter. This spread out the long d-spacing peaks, allowing more of
> them to be resolved, and is still a good solution for the magnetic
> structures in which they were interested. However, for structure refinement
> many peaks were still unresolved, and the shorter d-spacings needed for
> high atomic resolution could not even be seen.
>
> In a 1966 paper, Hugo already used intensities from overlapping Bragg
> peaks. Along with others with the same problem, he then tried to fit
> multiple peaks to overlapping regions, but with limited success. As well, a
> neutron powder pattern took a whole week to collect, and the local 
> Electrologica-X1
> computer <https://ub.fnwi.uva.nl/computermuseum//X1.php> was less
> powerful than the IBM-1620 - and programmed in Algol.  It was there and
> then that the brilliantly simple but profound idea arose of refining the
> crystal structure together with the parameters describing the peak
> positions and profiles all together, as published in the famous 1969 paper.
>
> Rietveld H M (1969) Journal of Applied Crystallography 22 65-71
> <http://scripts.iucr.org/cgi-bin/paper?a07067>
> “A profile refinement method for nuclear and magnetic structures”
>
> Hugo distributed his Algol refinement program
> <http://www.iaea.org/inis/collection/NCLCollectionStore/_Public/46/087/46087996.pdf>
> widely, but very few papers were initially published using the method.
> Discouraged by the limited funding available for neutron diffraction, he
> successfully applied to become head of the library department at Petten.
>
> One of us (AH), who had also completed his Ph.D. at Lucas Heights in 1970
> and who had moved to Harwell, encountered the same problems with neutron
> diffraction for structural transitions. On the advice of George Bacon, AH
> visited Hugo in 1971 and brought back Hugo's new Fortran-II version of the
> profile refinement program. A Harwell version
> <http://hewat.net/science/papers/1973_The_Rietveld_Program_for_the_Profile_Refinement_of_%20Neutron_Diffraction_Powder_Patterns_AERE_R7350-von_Dreele_annotations.pdf>,
> modified to model the anisotropic vibrations preceding structural
> transitions, was very successful, both at Harwell and with Brian Fender's
> students at Oxford, in particular Tony Cheetham and Bob von Dreele.
>
> In 1973, when the UK joined the EEC and AH moved to ILL in Grenoble,
> another Oxford student (WIFD) performed his first neutron powder
> experiments on AH's new D1A high resolution diffractometer, where a powder
> pattern took only one day to collect, and later only one hour. Again this
> work was very successful, and the number of papers using what Terry Sabine,
> in 1978, christened the "Rietveld Method" exploded, supported by new
> computer programs including those of the early Oxford-Grenoble champions
> Bob von Dreele and Juan Rodriguez-Carvajal. Yet it was not until 1977 that
> R.A. Young and colleagues applied the method to X-ray powder diffraction,
> leading to further rapid growth in the number of publications. Thousands of
> X-ray publications using Rietveld Refinement are now published every year.
>
> Perhaps the greatest acknowledgement of Hugo’s work was his receipt of the
> 1995 Aminoff Prize, awarded by the Royal Swedish Academy of Sciences, Two
> of us (AH and WIFD), along with Juan Rodriguez-Carvajal and Ivar Olovsson,
> were there to witness Hugo, accompanied by his wife and children, receive
> his accolade from the King of Sweden with typical modesty, delight and
> genuine astonishment at the pervasive influence of his Method across the
> sciences around the world. And beyond the world - in December 2012 he was
> thrilled to receive an e-mail from David Blake of the CheMin team of the
> Mars Science Laboratory rover, Curiosity, who wrote saying that *he did
> not think they could have convinced NASA to send an X-ray powder
> diffractometer to Mars without the Rietveld Method*.
>
> After almost 50 years, the Rietveld Method has returned to its origins in
> the Netherlands, with the third of us (LvE) completing a fast new high
> resolution neutron powder diffractometer (PEARL) on the Delft reactor. Hugo
> Rietveld lived to see that, and last year was the guest of honour at the
> opening of this new diffractometer. He, who had been honoured throughout
> the world for his achievement, was honoured in his own country by a new
> generation working with neutron powder diffraction and Rietveld Refinement.
>
> Having achieved all of that, and with a loving family and friends, he will
> surely rest in peace.
> Alan Hewat (AH), Bill David (WIFD) and Lambert van Eijck (LvE) July 2017
> ______________________________________________
> *   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE *
> <alan.he...@neutronoptics.com> +33.476.98.41.68
>         http://www.NeutronOptics.com/hewat
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