Chemistry at the Synchrotron

Meera –One place the path of chemistry is being paved is the Diamond Synchrotron, where everything from designer molecules, pitting corrosion and solar cells are being investigated. Diamonds Director of Physical Sciences, Trevor Rayment, explains the importance of this versatile subject...

Trevor – As a chemist, my passion and my background over many years, you won’t be surprised if I say that I think it’s the central science. It’s the science that so many other topics interface to and without which they wouldn’t succeed. So I think of it spanning into physics where high temperature superconductors came out of a chemistry background, solid state chemistry. I think of biology, chemists are the people who actually make the molecule that go to form drugs. Oh there are all sorts of areas such as catalysis, the clean cars, and new sources of energy, in all of those cases, a knowledge of chemistry is vital and in fact, chemistry makes all of these things possible. So perhaps you can see that I’m biased, but actually it’s a great subject and it’s central to so many other subjects.

Meera – And your own research within all if this is the use of chemistry and its role towards the field of materials science?

Trevor – Yes, I’ve been working on methods for many years that look at materials under their real operating conditions, looking at their surface chemistry and what I’m doing at the moment is working with a close colleague in Birmingham, Alison Davenport, to use those skills to look at corroding layers. To look at pitting corrosion, where little black dots in stainless steel corrode, it’s quite an important form of corrosion. Looking at the chemistry of those corroding pits.

Meera – And what have you been able to find out about them so far and is it the aim to then prevent this occurring?

Trevor – What we’ve learned is that the chemistry at the bottom of these corroding pits is important and for the first time we’ve identified the compounds, chemical compounds, that are found at the bottom of a corroding pit and now what we’ve discovered, or it’s Alison’s group that have really discovered, is how that chemistry influences the rate of corrosion. Often it is very difficult to prevent corrosion and so what you really want to understand is ‘how long will it be before it is really important and that is where the work is really progressing; taking the insights that we get from chemistry to predict the lifetime of a device. The lifetime, for example, of a canister that might store radioactive waste. The data that we’re providing, Alison’s group are providing, is allowing us to have really good models of how they might corrode over a period of a decade, 20 years, 10 thousand years.

Meera – Now you did mention that chemistry stems into a variety of fields such as biochemistry and physics as well, so what perhaps is some of the more current research taking place here at Diamond that stems into these areas?

Trevor – I think I’d like to point out 2 areas; one is the general field of energy. There is, as everyone knows, a real pressing need to reduce the amount of energy we use and reduce the impact of our industrial processes on the environment that we live in. So if we think about energy itself, then we might think about hydrogen storage. There has been a great deal of work over many, many years to improve methods for storing hydrogen and one of the favoured topics at the moment, one of the favoured areas, is the so-called metal organic frameworks. Central to all of this is designing frameworks of molecules that will absorb hydrogen and it turns out that the synchrotron is the ideal place to determine the structure of these complex materials. On the other hand there’s a lot of interest in designing solar cells. We’re all familiar with solar cells on roofs, they’re made of silicon and it’s very good, but silicon is an expensive material and it using quite a lot of energy to process it and the thought has been ‘can we make lighter weight, cheaper, solar cells made of polymers, plastics?’ and what matters there is knowing the structure and the behaviour of those layers, which are very thin, studying that and determining that and synchrotrons are ideal for that.

Meera – Now that work is done by David Lidzey who we’ve had on the podcast in the past and I think an interesting thing with that research is that although the efficiency may not be as great as the photovoltaics, the fact that they’re cheaper and more flexible and perhaps have a wider array of uses means that they’re quite important.

Trevor – If you’re trying to create new energy sources, then ultimately you have to compete with other sources on economic terms and into that equation come lots of things like the original cost, the efficiency, ease of installation, so it’s really quite complicated. And into an environment like that, having control of the chemistry is really important.

Meera – And so you’ve touched on these areas that chemistry stems into but what about, I guess, more fundamental chemistry, that’s looked into here?

Trevor – Another area that stems out of the control that chemists have over the shape of molecules is the notion that if you take a small molecule that is simple to make, how can you use that? Well one way of doing it which is very attractive is simply to take that small molecule, as like a Lego brick, and make it sufficiently clever that it’s got bumps and holes in it, so that those bricks will automatically assemble if you put them together. That notion of building big molecules from small molecules by using specially designed locks and keys is in fact the area of supramolecular chemistry.

Meera – That was Trevor Rayment, Director of Physical Sciences at Diamond Light Source.