EPSRC project for chemical crystallography and fibre diffraction using the ILL diffractometer D19

An award from the UK Engineering and Physical Sciences Research Council (EPSRC) has provided resources for a new large area position-sensitive detector on the D19 diffractometer at the Institut Laue Langevin (ILL). The modified instrument will have a detection solid angle that is larger by a factor of ~25 than in the current configuration. In addition to providing vast enhancements in quality for experiments of the type that are currently carried out, the upgraded instrument will allow completely new science to be undertaken. This development is of broad interest for neutron crystallography and fibre diffraction and for applications of these methods in chemistry, biology and physics. These communities have identified a clear need for a flexible monochromatic instrument that can carry out rapid neutron diffraction analyses to high resolution. The large increase in detection solid angle means that it will be possible to study the small single crystal samples most frequently encountered in this field and by exploiting tighter incident beam coIlimation, to investigate larger unit cells. For fibre diffraction work there will be the added advantage of being able to measure continuous diffraction.

The new detector

The new detector is being built by the ILL Detector Group and will be commissioned in mid 2005. The drawings shown below summarise the design and show how the detector will be installed.

Pictures showing the drawings of the new detector in place on instrument D19. Also shown is a photograph of a prototype device having the same basic design; Jean-Francois Clergeau shows Judith Howard (Durham - the PI for the project) how the wires are arranged. Alan Hewat (ILL) looks on.

Below: the complete detector (all except the electronics) just before being sealed in its vacuum vessel. Seen with it are Jean-Francois Clergeau, Sax Mason, Clive Wilkinson, Arsen Goukassov.

Applications

Chemistry & Materials

Charge density analysis

Accurate structure determination for crystal engineering

Studies of transition metal catalysis

Structural studies of new organic materials

Characterisation of weak intermolecular interactions involving hydrogen

Structure-property studies of opto-electronic/magnetic materials

Synthetic polymers

Biology

Biopolymers :

nucleic acids
filamentous viruses
cellulose
chitin
amyloid fibres

Biological crystallography :

Small proteins
Oligonucleotides

Examples

Single crystal neutron structure showing hydrogen bonding in a phosphonium aryl oxide (carbon, hydrogen, oxygen and phosphorus shown in dark grey, light grey, red and green, respectively). Broder et al (2002).

Revised structure for Kevlar, based on neutron fibre diffraction analysis (Gardner, English, Forsyth, Macromolecules 37, 9654-9656 (2004) )

Structures of [Cu2(m-O2CMe)4(O2HCMe)2] determined as part of an investigation of the effect of strong intra- and inter- molecular hydrogen bonding on molecular geometry in carboxylate coordination complexes (Vives et al (2001).

Hydrogen bonding in cellulose determined by neutron fibre diffraction (Nishyama et al, 1999; Langan et al, 1999)

References

Ahrens B, Davidson MG, Forsyth VT, Mahon MF, Johnson AL, Mason SA, Price RD, Raithby PR, J. Am. Chem. Soc., 9164-9165, 123, (2001)

Broder CK, Davidson MG, Forsyth VT, Howard JAK, Lamb S, Mason SA, Cryst. Growth Des., 163-169, 2, (2002)

Gardner,K.H., English, A.D., Forsyth, V.T., Macromolecules 37, 9654-9656 (2004).

Langan, P. , et al, J. Am. Chem Soc. 121 (43) 9940-9946 (1999).

Nishiyama, Y. , et al, Int. J. Biol. Macr. 26 (4), 279-283 (1999).

Vives,G., Mason, S.A., Prince, P.D., Junk, P. Steed, J.W., Crystal Growth & Design, 3, 699 (2003)

Thermal neutron diffractometer for single-crystal and fibre diffraction D19