The first microscopes gave humans the ability peer deep into the microscopic world, allowing us to see cells and microbes in unprecedented detail. Using the latest electron microscopes we are now able to see detail down to single atoms.
In fact, materials scientists can detect impurities in their latest compounds, atom by atom, using powerful electron microscopes aided by sophisticated modelling of what happens when the electron beam hits the material.
Dr Adrian D’Alfonso and a team of theoretical physicists at the University of Melbourne have developed these models and they are already helping groups around the world look at and understand nanomaterials in a way they haven’t been able to before.
“The biggest challenge facing electron microscopy has been in image interpretation—the image you record may not reflect the structure of the object that you are imaging,” Adrian says. “But using our technique you can tell what kind of atom you’re looking at and, most importantly, where it sits in relation to other atoms and what groups might be attached to it.
“And you can now tell apart a silicon atom and a phosphorous atom if they are next to each other in a material—something you couldn’t do before.”
For example, cerium-zirconium oxides are used in catalytic converters to convert toxic car exhausts into less lethal substances—but until recently the exact structure of these catalysts was disputed because the catalysts were too small to use crystallography or traditional electron microscopy.
“Working with Spanish colleagues from the University of Cadiz, we used our technique to determine the actual structure of the nanoparticle with the aim to better understand the particle’s catalytic properties,” says Adrian.
In 2011, his research won Adrian the Australian Institute of Physics Bragg Gold Medal for best PhD thesis.