A1258567809ZHylP

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LAUE DIFFRACTION The key for NEUTRON DIFFRACTION
from submillimetric SINGLE CRYSTALS
? The new Laue diffractometer VIVALDI at the
ILL M.H. L-C1, G.J. McIntyre1 and C.
Wilkinson1,2 1 Institut Laue-Langevin, Grenoble
France 2 Chemistry Dept, Durham University UK
ECRYS-2005, Cargèse France
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Why scientists need LAUE NEUTRON DIFFRACTION ?
Actual trends in condensed matter research -
New materials with more and more highly
sophisticated composition ? chemical contrast
(H, light elts) ? delicate synthesis -
Magnetism - Complex external conditions (high
pressures, very low temperatures ) - Out of
equilibrium phenomena
With interest for structural properties but also
for electronic properties, The coupling between
both appearing to be more and more crucial,
Indeed it has appeared in the last decade that it
is more interesting to look to non-linear
interaction which have the advanteg to enhance in
a much more efficient way properties (inetrest
for the potential applications with materiels
wich can be able to excute different tasks with a
much smaller amount of energy)
ECRYS-2005, Cargèse France
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M. von Laue, Nobel Lecture Stockholm
(1915) Detection of X-ray interferences
- white beam diffraction technique - Fixed
2-dimensional detector - single crystal
ECRYS-2005, Cargèse France
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Fundamentals of Laue diffraction - white beam
diffraction technique - fixed detector - single
crystal
Problem of multiple scattering
but not for 83 of spots (with ?min lt ? lt
2?min)
Ewald sphere
Multiple scattering but not for 83 of
spots (with ?min lt ? lt 2?min)
Laue suite http//www.ccp4.ac.uk/main.html
ECRYS-2005, Cargèse France
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Laue diffraction white beam ? end position on
neutron guide
- LADI for proteins (cold neutrons )
- VIVALDI Very Intense Vertical Axis Laue
DIffractometer
- OrientExpress crystal testing instrument
(historical neutron Laue diffractometer J.C.
Marmeggi)
ECRYS-2005, Cargèse France
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VIVALDI Very Intense Vertical Axis Laue
DIffractometer - white beam for maximum flux -
thermal neutron for maximum reflectivity (0.8 lt ?
lt 5.2Å) - large image plates (Gd2O3 in
BaFBrEu2) for 8 sterad (288 horizontally x
104 vertically) - high resolution (200x200?m2)
and large dynamics range (108) - vertical
geometry to allow complex sample environments ?
factor 10 to 100 gain over monochromatic data
collection (as fast as powder diffraction!) ?
possibility to study small crystals
ECRYS-2005, Cargèse France
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• Data reduction of conventional structures
  (mostly) by programs of the CCP4 X-ray Laue suite
• www.dl.ac.uk/SRS/PX/jwc_laue/laue_top.html

! Cell parameters known from e.g. powder
diffraction
Vitamin B12 10 000 reflections in each 8-hour
exposure, mean I/?(I) 10, 6 mm3 crystal G.
McIntyre, S. Mason, Wagner, Luger
ECRYS-2005, Cargèse France
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First experiments on VIVALDIVery fast data
collection over all of reciprocal space for very
small samples
10 kbar TiZr pressure cell !!
ECRYS-2005, Cargèse France
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Concluding remarks You want to have precise
informations (light elements) You want to
work under complex environment conditions (high
pressure, very low temperature, magnetic
field) Neutron diffraction can do a lot for
you even if you do not have large single
crystals !
ECRYS-2005, Cargèse France
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