SuperSTEM is funded by the Engineering and Physical Sciences Research Council (EPSRC) and has three electron microscopes that UK scientists can use. The newest was unveiled last month: a £3.7 million ($5.5 million) Nion Hermes Scanning Transmission Electron Microscope that EPSRC says is one of only three in the world. It can image objects a million times smaller than a human hair.
A facetted nano-void in diamond. SuperSTEM was used to understand the origin of brown colour in natural diamond. Image
“Essentially we’re able to look down at materials or most things that we put in the microscope all the way down to the atomic scale,” said Quentin Ramasse, scientific director of the SuperSTEM lab. “So we can regularly see single atoms and atomic columns.”
That’s because electron microscopes use a beam of electrons rather than photons, as you’d find in a regular light microscope. As electrons have a much shorter wavelength than photons, you can get much greater magnification and better resolution.
HAADF micrograph of a copper and silver rich precipitate in an aluminium-based alloy. Image:
Why would you even want to see something in that much detail? The most obvious, Ramasse said, is because we’re always trying to miniaturize devices, which means we need to miniaturize parts like transistors and semiconductors—“and that means you need to design materials or materials’ components that are really smaller.”
It gets to a point where modifying a material even by an atom or two could change its properties. Think about wonder material graphene, for instance: a 2D sheet of carbon atoms. Add another atom here or there and you’ve changed the material and potentially modified what it can do. Keeping an eye on the exact structure is therefore important.
HAADF micrograph of a plain, pure graphene sheet. Each dot in this image is a single carbon atom. Image:
One project SuperSTEM has been involved with centres on another 2D material, molybdenum disulphide. This can be used as an industrial catalyst, for example to remove sulphur from fossil fuels. Danish chemical company Haldor Topsoe used the electron microscopes to explore how rearranging its atoms could affect its catalysis properties.
To some extent, it’s simply a matter of being able to see what’s actually there.
Other applications could include nanomedicine—Ramasse gave the example of needing to check that a drug molecule is sufficiently attached to a nanoparticle acting as a drug delivery vehicle, as “you want to make sure the link is solid so it doesn’t disappear in the body.”
And while the most obvious applications are in chemistry, he said the microscopes are also used for some things “a little bit more out there,” like looking at the crystalline structure of dust particles from meteorites. It’s a close-up for the far-out.
This story is part of The Building Blocks of Everything, a series of science and technology stories on the theme of materials. Check out more here: