We’re at a good point in our experiments. We are taking data, consistently, that we believe to be of high quality.

Actually, things are going quite well right now. We’ve got a nice rhythm going where we measure sample A for 10 hours, exchange samples (takes a couple hours), and then measure sample B for 10 hours. During the exchange a couple of people are needed, but during the measurements the experiment just collects data with the computers now automatically adjusting the various parameters. To add to this, while we measure one sample the other sample is being re-prepared. We’ve got relatively little “down time” in terms of not using the photons available due to us changing things out. And once we’re measuring, we’ve got it set to just “go.”

Aside from the welcome reduction in stress to the experimenter this provides, I think it genuinely makes for better quality data and experiments. By operating this way we (hopefully) eliminate many possible sources of change to the experiment except for the exact ones we’re looking to introduce.

In this case we’re doing x-ray scattering from a surface in electrochemical solution while it is under electric potential control. This kind of science has all sorts of interesting pieces to it related to electro-deposition of material, catalysis, and corrosion study.

What you can see above is the sample, it’s cell and support we’re using. The little gold/yellow cylinder in the middle is the actual sample of interest (at the moment at least). Here it’s a small Au (gold) crystal that we’ve got in a dilute perchlorate. By applying an electric potential from the sample surface to a counter electrode we are able to control the conditions of the atoms on the surface. This is all well studied. Our contribution is to be able to measure how faster certain processes are occurring on the surface. Some things are easy to see and have been well documented before. But other changes have been effectively invisible to conventional in-situ surface probes (or at least very difficult to measure) . However, in our case the x-rays are sensitive to such changes are we aim to record them.

To be fair, it’s not just any x-ray source that we can use. There are in fact very few places in the world where we’re capable of making such measurements.

For an anecdote, you may also notice a “strained” or hazy appearance to the above picture. That’s because of a particular ad-hoc solution that has become standard practice. Not everything is done with such precision and delicacy as most people imagine. Often times we’re faced with problems for which we have to come up with solutions on the fly. In this case it’s important to keep the entire sample cell in a nitrogen rich environment (or rather to keep it in an oxygen poor one). But we need to get x-rays in and out with minimal fuss. The solution? Ordinary sandwich bags (of the thinest variety). They are transparent to the x-rays (as well as ordinary light which makes it easier to work with), and we can simply inflate them with nitrogen. They’re non-reactive, don’t add any contaminant, are cheap, can be disposed of after a single use, and let us protect the sample cell. Granted, there’s still an ultra think polypro film covering the solution and sample. But this helps keep any outside oxygen from getting to that film. So, in addition to the ubiquitous aluminum foil we have everywhere, add sandwich bags.

Well, for now, steady as she goes.