Diamond Synchrotron, News

Cooling the ‘excited state’

Well I find myself, borrowing a few minutes to write the blog before going to bed at 10am on a Saturday morning….would be height of totally decadence if I hadn’t been hold-up in a room the size of a storage container for the last 17 hours !!

It’s not as bad as it sounds, yesterday John, Asheley and our host, Fred Mosselmans had great fun with liquid nitrogen while I slept the day away reading for the night shift. I was very disappointed to miss all the full with liquid nitrogen. OK, a little chemistry background…sorry but this is a science blog. Our experiments rely on us using an x-ray beam to ‘excite’ the metal ions we wish to characterise and as they return to there normal state they emit fluorescence with very specific properties and it is this fluorescence that allow us to do tell where and in what ‘form’ the metals are in, in the biological tissues. Unfortunately, some metals get too ‘excite’ and generate damaging side products (free radicals), that can destroy the very chemistry you are investigating. As Fred predicted, Manganese is one of these challenging metals.

So this gives a bunch of Professors the perfect excuse to play with liquid nitrogen….we use the liquid nitrogen to cool the sample to -196oC (77 Kelvin) to try to prevent it from getting too ‘excited’ (probably a solution my mother would have liked to have had when I was a child !!). But there’s a hitch, cool most things, including super glue down to these temperatures and it becomes very brittle….so John and the guys had great fun playing with accessories that look like an endoscope made for an elephant which steams with liquid nitrogen….I love science (pictures to follow).

Camera 360


But, unfortunately for me, by the time I got up the excitement was over. Cooling to -196oc had not work, the samples were still getting too ‘excited’. This is where we are glad that the beam line scientists with which we work here at Diamond are some of the best in the world. They have very recently developed a new method of acquiring the data we need while only exposing the sample to 0.15 seconds of x-ray at one time (this is repeated so that the total excitation time does not exceed 8 seconds). In addition this method lets us not just map where the metal is but also map the state of the metal, this innovation is called XANES mapping (not scanning a single point, that is old hat, mapping your speciation using XANES mapping, believe me this is very cool!!). So I spent a very happy and productive night XANES mapping Snail digestive glands….and I will post pictures later but for now I have to sleep…..night night.