Small Angle X-Ray Scattering (SAXS)
It also acts as a bridge to the Australian National synchrotron, the ultimate X-ray analysis tool, which the New Zealand government recently invested in. Both instruments have had co-investment from other Centres of Research Excellence (CoREs) and are strengthening links across the New Zealand science community.
About the Instrument:
SAXS gives you information about structure on the scale of 1 to 150 nanometres – the next scale up from the Spider Diffractometer. Rather than describing the way single atoms pack together to form crystals, it tells you about the size and shape of larger structures such as macro-molecules, nano-particles or droplets of oil in emulsions. It can also tell you how these individual structures pack together in solid, liquid or film samples. The SAXS has two imaging systems – a line collimated system, suitable for analysing materials with uniform structure in all directions, and a second ‘point source’ system which can tell you about the direction or orientation of structure in materials. The point source system was purchased by the Riddet Institute for food, nutrition and health research.
The SAXS fills a very important gap in scale for nanotechnology. Chemist Kate McGrath came to the MacDiarmid Institute after spending her PhD and two post-doctoral fellowships studying SAXS at top overseas universities. Back in New Zealand without the equipment, she had to give it up but now all her experience is coming to the fore. Kate’s group are using the SAXS to analyse self assembling liquid systems such as emulsions, liquid crystals and mono-layers. The technique is also a perfect complement to electron microscopy for the many researchers in the Institute that synthesise nanostructures. While electron microscopy gives you a localised picture of the nano-structure, the SAXS provides averages across the sample. This kind of statistical information is essential for developing applications. “If you are doing anything with those particles then you need to have the big picture,” says nano-particle researcher Conrad Lendrum. Conrad has been using the SAXS to analyse a type of nanoparticle with a shell made of one material and a core made of a different material. Using electron microscope images with SAXS measurements has enabled him to work out how thick the shell is compared to the core. He believes the SAXS will improve the quality of papers considerably and give researchers a competitive edge over many international groups who use electron microscopy alone.
“This is a technique for New Zealand,” Kate explains, “it’s just a matter of getting people to understand what they can do on it and getting them to try it out.” She is happy to help them work out how SAXS could augment their research program. The technique shows particular promise for biological systems, which are rich in structure at the nano-scale. MacDiarmid biologist Juliet Gerrard from Canterbury University is already using the instrument to study protein and enzyme self-assembly. With co-investment from both the Riddet Institute and the MacDiarmid Institute, the SAXS has strengthened relationships within the New Zealand science community and it’s bound to spur many more cross-disciplinary collaborations in the future.
When someone says they are studying soft materials, you may think of cuddly toys or velvet cushions, but to MacDiarmid researchers it means the long chains of molecules that make up cellulose fibres, dairy-based casein micelles and protein filaments in hair or food. These biomaterials form an intermediary hierarchy between the atomic and single molecule […]