Meeting Report - Small Angle Scattering Special Interest Group

2 - 3 July 2007 ILL, Grenoble

Link to Programme and abstracts.

This meeting was organised by Richard Morris (Morris Analytical X-ray), Dave Taylor (ICDD) and Jeremy Cockcroft (UCL) and hosted by the ILL and ESRF on the joint site at Grenoble. Arriving in Grenoble, the first impression is of how stunningly beautiful the scenery is. Lying in a valley, surrounded by the Alps, this would certainly be a pleasant setting to live and work. On to the site itself and after the briefest of stops at security we settled into our en suite rooms at the guesthouse.

Day 1 - 2nd July

Photographs above inside ILL are Copyright : ILL / Artechnique©

Photographs above of beamline D11 are Copyright : ILL / Artechnique©


Photographs above of beamline D22 are Copyright : ILL / Artechnique©

After coffee, we got down to the real business of the day. Peter Laggner (Institute of Biophysics and Nanosystems Research, Graz) gave a broad overview of the techniques of SAXS and SANS, starting with the basic theory of scattering. A brief history of the development of these techniques led into a discussion of systems suitable for SAXS/SANS analysis and the "4 limiting cases" for the treatment of data from such studies. Improvements in laboratory based SAXS equipment were presented and the point made that many studies could now be conducted, more conveniently, in the laboratory without having to travel to a central facility such as the ESRF.

This was followed by Françoise Ehrburger-Dolle (Laboratoire de Spectrométrie Physique, CNRS-UJF) who described smectic ordering in side-chain liquid crystal polymers (LCPs) and in LCP-silica nanocomposites. She described the types of polymers that can form liquid crystals and the phenomenon of inter-digitation. A series of SAXS experiments at different temperatures showed clear changes in the crystal layer spacings at specific temperatures. This was attributed to a change in the degree of inter-digitation within the system. Results from further studies, in which the LCP's were confined within a silica xerogel, suggested that this change was inhibited for LCP's residing in the smaller pores where they may not have the space to rearrange.

Richard Görgl (Materials Centre, Leoben) presented the NanoSTAR system from Bruker, a laboratory solution for SAXS studies. Recent improvements to this system were reported, including a new microfocus X-ray source and a radiation-hard detector that requires no beam-stop. A study of crack propagation in polyvinylidene fluoride (PVDF) films, using this system, was presented and a comparison made with similar data collected using a synchrotron source.

Left to right: Peter Laggner, Richard Goergl, Françoise Ehrburger-Dolle, Darren Spruce (Chair)

An excellent lunch was followed by a presentation by Charles Dewhurst (ILL) on D33 - a third Small-Angle Neutron Scattering (SANS) instrument to be installed at ILL. The new instrument will be capable of experiments in high magnetic field strengths, something previously impossible at its predecessor D22 due to that instrument's proximity to extremely sensitive spin-echo experiments. Combined with a neutron polariser, D33 will be a superb instrument for the study of magnetic materials and superconductivity phenomena.

Adrian R. Rennie (Uppsala) presented results of in-situ studies of flowing samples with SAXS and SANS. The example given was surfactant templated synthesis of mesoporous silica. Contrast matching techniques were used to remove the effects of silica from the scattering data and reveal the structure of surfactant micelles present in the system. It was shown that, while the micelles have a strong influence, there is a densification step late in the crystallisation process that determines the final structure. Further experiments showed that the addition of salts to the synthesis could affect the structures obtained by modifying the surfactant micelles.

Alberto Saiani (Manchester) then talked about creating 3D-networks and hydrogels from self-assembling peptides. This study was based on synthetic octa-peptides, which were designed to self-assemble into rod-like structures solution. Changing the octa-peptide was shown to alter its self-assembly behaviour in solution, longer or shorter rods could be obtained. Hydrogels formed by these differing systems had markedly different morphologies. The longer rods gelled by simply entangling like spaghetti, while the shorter rods formed a true 3-dimensional network with branching points.

Left to right: Jeremy K Cockcroft (Chair), Alberto Saiani, Charles Dewhurst.

Alexis Deschamps (SIMAP, France) summarised some of the recent progress made in characterising precipitates in metallic alloys using small-angle scattering. The microstructure of these precipitates has a strong influence on the mechanical behaviour of the metal. This was illustrated with a study of Aluminium-Zirconium-Scandium alloys, in which precipitates of ZrSc are found, with a Scandium rich core surrounded by a shell that is relatively rich in Zirconium. SAXS was used to characterise these precipitates in terms of their size, composition and thickness of the shell.

This was followed by Andrew Harrison (ILL) who discussed applications of microwaves in materials science. The ability of microwaves to selectively heat one component of a system was presented. This effect could be utilised for "quick-start" catalytic converters in which the catalytic metal particles are rapidly raised to their operating temperature, increasing the efficiency of the converter. The effects of microwaves on biological materials were also discussed. It was shown that microwaves, at wavelength used by mobile phones, had a small heating effect on phospholipids (which form cell membranes within the body). Is this bad news for the telecommunications industry? Probably not, the size of the effect is too small and mobile phones simply don't emit enough microwaves.

Jennifer Hiller (Diamond Light Source Ltd) followed this with details of I22, the new beamline at Diamond. Specifically designed for work on non-crystalline systems, I22 is now ready to receive its first users and Jennifer extended an invitation to all for applications for beam-time. This came with the caveat that Diamond is still a very new facility and that early users should expect some teething problems.

Peter Laity (Cambridge) ended the day with details of recent work using SAXS to investigate the deformation of polymeric powders undergoing compaction. Understanding this process is of particular importance to the pharmaceutical industry for the making of pills. The use of SAXS to study powder compaction has not previously been reported in the literature. After a discussion of possible mechanisms for the compaction of powders when loads are applied, Peter demonstrated that powder compaction can be understood in terms of the packing of the particles at low pressures, followed by so-called affine deformations in which the particles change shape to give greater interfacial contact and hence better bonding between neighbouring particles.

Left to right: Richard Morris (Chair), Jennifer Hiller, Peter Laity, Alexis Deschamps, Andrew Harrison.

The evening provided an opportunity for socialising with the conference dinner. A short coach ride into town brought us to "La Panse" where we were able to enjoy some of the cuisine for which the region is justifiably famous. This was accompanied by plenty of good red wine, a most welcome and enjoyable end to the first day.

Day 2 - 3rd July

The second day was kicked off by Jean-Paul Simon (SIMPAP) who spoke about ultra low k dielectrics for microelectronics. In order to reduce "cross-talk" between the copper tracks on integrated circuit boards, nanoporous materials have been developed to make use of the very low dielectric constant of air. Jean-Paul spoke about how the pores in these materials are produced and the use of grazing incidence SAXS (GISAXS) to characterise them.

Christian Riekel (ESRF) followed this with an introduction to small- and wide-angle X-ray scattering (SAXS/WAXS) using micron- and submicron-sized synchrotron radiation beams. The small size of these beams allows scanning of a sample to build up a composite "image". This was demonstrated with a study of starch grains showing the internal morphologies. The high flux of synchrotron radiation allows for time resolved studies, once again demonstrated with starch, this time determining the kinetics of starch hydration. One of the stranger applications of this technique was a study of spider silk, drawn directly from the spider's spinnerets. We were assured the spider did not mind being strapped to a table, inches from a synchrotron x-ray beam.

Next, Tim Wess (Cardiff) discussed structural hierarchies in biological molecules. The properties of biological materials depend strongly on the arrangement and interactions of the molecules that comprise them. Using the example of fibrillin, an elastic component of connective tissues, Tim showed how the arrangement of the molecules could be elucidated from SAXS data and how this related to the mechanical properties of the tissue.

Left to right: Adrian Rennie (Chair), Christian Riekel, Jean-Paul Simon, Tim Wess.

Vladimir Kogan (DANNALAB & PANalytical BV, The Netherlands) presented the results of SAXS evaluation on nanoparticles, polymers and biological macromolecules conducted on the conventional X'Pert MRD diffractometer equipped with dedicated collimation system, optics and source.

Wim Bras (ESRF) then gave an entertaining talk titled "The Joy of SAXS and other toys". Using the example of crystallization in glass ceramics, Wim demonstrated the enormous benefit of combining SAXS data with that garnered from other techniques when elucidating structures and determining kinetics. Ideas that are suggested by one set of data can be confirmed or rejected based on other results.

Finally, Richard Morris (Morris Analytical X-ray) gave an overview of the history of Morris Analytical X-ray and shared some his knowledge of surfactant meso-phases.

Left to right: Wim Bras, Dave Taylor (Chair), Vladimir Kogan, Richard Morris.

To close the meeting, Dave Taylor, thanked all speakers and delegates for making the BCA's first foray onto foreign soil such a success. Thanks were also given to the meeting's sponsors, without whom we would all have gone hungry on Monday night.

After the meeting proper, there was an optional tour of the ESRF located just next door to the ILL. Having heard so many talks about synchrotron SAXS experiments, I was keen to see the sort of kit used to perform them. Inside the synchrotron building, there is the same sense of massive complexity as at the ILL but a much more enclosed feeling due to the curvature of the ring. Wim Bras once again demonstrated his enormous enthusiasm for his work whilst describing the features of his own beamline (DUBBLE).

Andy Smith
UCL

A French bursary students impression on BCA's meeting on small-angle scattering

     Everything started at the gate of the joint site of ESRF and ILL in Grenoble. After the control check point, delegates were to meet on the main building of ILL site, in order to receive a few security advises and to start the meeting by a tour of the facility. A few minutes later, they were separated in two groups leaded by the two heads of line D22, I. Grillo and C. Dewhurst. Just a few seconds to talk with delegates and we were entering the airlock between the main building and the reactor. Heart bumping, air pumping and that's it we're in! Just behind these heavy concrete walls, uranium is producing high energy neutrons directed to more than 20 lines running through 50 meters long for some of them. All around is crowded with huge instruments, spectrometers, monochromators, lines being constructed…
     Before we even knew it, the tour of the experimental hall was finished, back to the airlock, and contamination check…3, 2, 1, all right no neutrons on my body let's go to the neutrons guide halls. Both these guide halls are amazingly huge, around 100 meters long for each and are housing lines dedicated to SANS and WANS, diffraction, reflectometry, spectrometry all of these accessible to researchers from all around the world (be prepared to wait a few months though). The tour finished it's time for a coffee break and to start working, but before take the time to notice the amazing mountains surrounding the joint site.

     After an exhaustive introduction about SAXS and SANS by Prof. Laggner, researchers presented the various applications of the X-rays or neutrons scattering. Coming from a material speciality, I was only aware of a few of them but one would be really surprised witnessing all the possibilities of scattering on the study of soft and hard matter. Of course, you can estimate the size and the volume fraction of a given population inside your sample whether it be a metal, a powder, a polymer liquid or not, or a living tissue such as spider web! But you can also get some information about ordering in your system, do some in-situ experiments on flowing fluids or on living tissues such as cornea muscle fibres, identify the interacting groups of a polymer chain and even model the effect of microwaves generated by cell phones on the proteins of our brains. Finally one would discover less known techniques such as GISAXS used to study thin layers and EXAFS.
     Added to that, the partners of the meeting presented us with some of their products for small and wide angle scattering to be used in the lab and overall, the details of the project of a construction of an additional small angle beam line at ILL, the D33 line, and the different steps of the mise-en-route of the beam for a new small angle line at Diamond (UK) were given. Finally a tour of several lines of the ESRF was also proposed at the end of the meeting.

     Delegates were also given the occasion to discover French cooking and wines at the conference dinner whom organisation was courtesy of the meeting sponsors. This very informal meeting was a real success, with some really good presentations, and excellent reception and organisation from the joint site. I can only invite you to keep informed on the next meeting of BCA's on small-angle scattering or at least to take one of the annual tours organized by the joint site to discover the joys of small angle scattering.

Benjamin Decreus
SIMAP - INPGrenoble-CNRS-UJF