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I work in a Chemistry department but I’m not often found wearing a labcoat.  I do very simple experiments to grow my crystals, but spend most of my time using big equipment to allow me to look inside crystals and see the arrangement of the atoms and molecules.  Atoms and molecules are too small to see with the eye and even with the most powerful optical microscope in the world!  We just can’t see them using light.  So we have to use X-rays instead which we can’t see with our eye and we need to use a computer to turn the X-ray pattern into a picture of the atoms and molecules.  You can learn more about what this means by watching these youtube cartoons.  https://www.youtube.com/watch?v=uqQlwYv8VQI  https://www.youtube.com/watch?v=Z7hXiKiZZPs

Or you can find out more about crystallography here.

I am trying to understand how molecules are connected together inside the crystal and how this affects the way that they work.  For instance, some of the substances that I make change colour when you heat them up and cool them down.  These could be useful as temperature sensors.  Others change colour when you put them under pressure.  I also shine lasers at crystals and this can change things like the colour, the luminescence, the way it behaves when you flow an electrical current through it or the way it behaves when you apply a magnetic field to it.  We are working to make things that are useful as sensors, data storage materials, colour changing devices (e.g. colour changing paint for your car!), or to find ways to make medicines more effective at getting into your bloodstream.  All of this is just by playing tricks about how we get things into a solid, without changing the way that the atoms are connected together into molecules.

In the lab, I try and grow crystals that we can use in our experiments .  The is exactly the same as if you have ever tried to do using a crystal growing kit, we dissolve the solid up in a liquid (we call it a solvent) and we let the liquid evaporate off slowly to try and give us nice, single crystals.  We can tell that they are single by looking at them under a microscope and if they are fairly transparent with a regular shape and clear edges, there is a good chance that it will be good enough to use in an experiment.

A crystal is special because the atoms and molecules are arranged very regularly inside it much like a three dimensional brick wall.  You can see an example of how the atoms are arranged in things like salt by this jelly baby and cocktail stick model or by looking at this model which is a scaled up version of the inside of a crystal of 3,5-dinitrobenzoic acid

We put the crystals on a diffractometer which is a machine which fires X-rays at the crystals. We usually cool the crystals down using liquid nitrogen to make the atoms move around less .  We have a detector which works a bit like a CCTV camera but it sees X-rays instead of light.  We see a pattern on the detector as demonstrated by my duck, quackers .  By looking at the places where we see spots, we can do some maths using a computer and get a three-dimensional picture of the arrangement of the atoms and molecules inside the crystal.  By looking at the arrangement of atoms and molecules in the crystal, we can work out how the solid does the job that it does.

Sometimes because we are trying to do a complicated experiment, or because the crystals are too small, we go to a synchrotron like Diamond Light Source to do experiments.  This creates very high powered X-rays and means that we can do our experiments faster and on smaller crystals .  These X-rays are so strong though, that they often burn holes in the crystals!

In our lab in Bath, we can shine LED lights onto our crystals or squeeze the crystals between two diamonds, or heat and cool them.  This helps us to understand how the materials might be useful for storing information or as sensors for temperature and pressure.  We can observe the crystals under a microscope as we do this too so that we can see any changes like colour changes which would be useful indicators.  If we want to get more extreme, we can zap the crystals with lasers but we have to go to Diamond Light Source to do that and the experiments take several days to set up and then several more to collect the data!

I spend a lot of time either at a microscope or at a computer.  My desk isn’t very tidy but it has everything I need around it, including a good supply of different types of tea which I use to fuel my days!  I will typically collect some data, then analyse the data and try and understand why the arrangement of the atoms and molecules is helping or preventing an interesting property of the solid material.  There is often a lot of head scratching!  I also look after a PhD student so we often talk together about what the we are seeing.