Nanotechnology

Nanotechnology, the science and engineering of the small or, equivalently, the study and manufacture of devices of nanometre scale, has the potential to impact profoundly on our way of life. Nanoparticles, with properties distinctly different from those of the bulk material, can be exploited in a multitude of of potential technological applications, such as non-linear optical switches. Accordingly, funding agencies worldwide are allocating considerable resources towards nanoscience and, in Australia, the Australian Research Council has designated nanoscience as priority research area.

Synchrotron based powder diffraction combined with x-ray absorption spectroscopy (XAS) is the ideal technique, potentially the only technique, for structural parameter determination of nanoparticles at the atomic scale.

Many nanomaterials have a disordered structureand conventional powder diffraction is unsatisfactory, so it is necessary to use pair distribution function (PDF) analysis. Such analysis requires the data to be collected to a much higher q-range than is possible with a conventional powder diffractometer and high energy synchrotrons are emerging as the only source capable of this.

XAS also provides information on long range order and disorder and studies using this technique have been initiated by Australian scientists to study both semiconducting and metallic nanoparicles in a variety of matrices for application to photonic devices and chemical catalysis, respectively. Given that both the optical and catalytic properties are governed by the structural properties, XAS structural determinations have the potential to yield fundamental insights into the unique nature of science at the nanoscale.

In addition, the ability to focus the x-ray spot size down to the order of 0.1 micron in microfocus spectroscopy means that for the first time it will be possible to analyse the chemical composition of individual nanoparticles.

There is clear overlap in biotechnology and nanotechnology where biological molecules are used for non-biological purposes. Knowledge of the three dimensional structure of antibody molecules obtained through the use of synchrotron based techniques is leading to the development of biosensors that are able to detect both biological and other chemical moieties. Rapid developments in the field of diagnostics are enabling the design and construction of biosensor chips using these anti-body molecules as the detection front-end to facilitate the diagnosis of cancer and other disease states. This is proving useful in particular for future medical diagnostics "point of care" technology. There is also an increasing interest in using biological moleucles as sensors for the detection of chemicals and pathogens. This has particular relevance in the area of the detection of chemical and biological weapons. Currently there are programs with CSIRO and CRCs that are directed twowards finding solutions to these goals.

Devices exploiting nanotechnology developments such as biosensors, usually require micro-machined substrates to support the nano-layers, and provide intelligence or other functions such as microfluidics. Synchrotron based lithography provides unequalled capability to produce such substrates with truly deep three dimensional structures and optically flat surfaces, and will become an essential tool as nanotechnology develops.

The chemical compatibility and reactivity of surfaces is also an important factor in producing nano-layers, and the synchrotron-based soft x-ray techniques will be important for characterizing these surfaces as well as the layers.