The pace of modern technological development - from microelectronics to catalysts, to coatings - is driven by fundamental breakthroughs in fabricating novel nano-structured materials. Such materials often promise unique or enhanced physical characteristics, such as strong magnetisation or unusual reactivity. These characteristics will derive from, but can also be compromised by, subtle, atomic-scale structural variations. In each case, nano-resolved characterization is essential and full understanding of a material demands multiple state-of-the-art experimental probes. The probes used in my research include beams of electrons, atoms, ions, and photons, as well as physical devices such as the tip of an atomic force microscope. Each probe has its advantages and its limitations and the best studies of nanostructured material combine the results from several probes in order to develop a complete description.

A selection of my recent projects is given below. The uppermost projects derive from my time in Glasgow, whilst some of those below are based on collaboration with colleagues in Cambridge, where more information can be found.

• Pulsed Laser Deposition
• Nanoparticle characterization
• Structural characterization of nanomaterials
• Analytical electron microscopy
• X-ray spectroscopy
• Atom interferometry
• Development of Scanning Helium Microscopy
• Studies of thin film growth
• Medium energy ion scattering
• Gas detection via field ionisation from carbon nanotubes

Structural analysis via Medium Energy Ion Scattering

Medium energy ion scattering (MEIS) uses a collimated beam of high energy ions to probe surface structure with extremely high precision and elemental discrimination. I have been involved in several studies of thin film growth processes, most recently looking at the deposition and alloying of magnetic thin films. Experiments are conducted at the UK MEIS facility at Daresbury, now run by the Science and Technologies Facilities Council. In a typical MEIS experiment, the sample is illuminated with 100kV He or H ions, using low-index scattering geometries that are chosen to afford surface-specific structural information. By exploiting the fact that substrate atoms are shadowed by their overlying neighbours in certain crystallographic orientations, it is possible to determine the interlayer spacing, atomic arrangement and layer-wise composition with great accuracy. The sensitivity of MEIS to atomic mass is particularly valuable as it affords elemental discrimination. Each element appears as a separate band in the two-dimensional data sets (see figure, left); data sets are then analysed by means of best-fitting to structural simulations in order to triangulate the position of surface atoms. Publications: 9,11,13.