Thursday, 16 April 2015

Lab work, or what I did with my summer (2013)

This summer proved to be an interesting experience. For the first time, I was permitted to work in a research laboratory, doing experimental science. Not the stifled, predictable, has a correct answer work done in undergraduate laboratories but the open ended field of research science. I had agreed with Professor Andy Ellis of the University of Leicester to work in his laboratory over the summer, and the experiment was much more chemical physics, than physical chemistry. We were synthesising nanoparticles in helium nanodroplets. The first time I'd ever been able to do any such work and certainly an interesting experience. 

The door to the "office"

The helium nanodroplet experiment is an interesting area of research. The droplets themselves are cooled to a temperature of 0.37K, and hence the helium is superfluid. This means two things, the first being that molecules are free to move about inside of the droplets and also that due to the low reactivity of helium they don't form interactions with the helium nanodroplet and thus provides a fantastic way of capturing and holding particles to perform tasks like spectroscopy. This is aided by helium's transparency to most forms of radiation. An off shoot of this is the fact that the size of the droplets can be controlled and thus the size of particles within these meaning that the helium nanodroplet systems provide a novel and interesting method of synthesising nanoparticles with very tight size control.

One of the first tasks we had to do was test the oven we were using to introduce metal into the helium beam. This was done on an ultra high vacuum rig to simulate the conditions that the oven would be operating under. This also ensured that most of the water that had built up on the metal surface would be dissipated by evaporation. 

The oven in operation

The rig it was operating inside of

Eventually this was moved to the main rig. Normally, at this point I would show a picture of the main rig that was being worked on but unfortunately I couldn't find a good enough picture to show it off. It's a big piece of kit - kind of 2.5-3m long apparatus.

We produced nanoparticles fairly quickly containing aluminium. It was especially interesting to see these under a TEM however I cannot post them here as they are publication pending. Eventually we turned our attention to what we were seeing in our mass spectrum.

Now, a few years ago, some German scientists published a paper saying that aluminium atoms trapped in helium nanodroplets were separated by layers of helium and hence would not cluster together. Now, I know of work done that shows that excited electronic states of aluminium tend to the surface of the droplet and I also know of work done that shows that ground state aluminium does not. They had very limited evidence for their claim that these layers of helium existed. But one thing is certain, clusters would not be seen in the mass spectrum.

Yet, this is exactly what we saw!!!  Imagine our surprise. Even more interestingly was that these followed a near magic number progression! Even more interesting. The findings were published then in the Int. J. Mass Spectr. in 2014 and my name was on the paper!! Hopefully the first of many scientific papers in my name!!

It was a great summer and I was keen to repeat the experience again! Even if there were some ups and downs.

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