Things are progressing in many ways better than expected, though we're still struggling to get to the point of doing science.

By the start of the second day, we had the sample in the diffractometer, and everything was aligned. The surface was even "kind of" located. Not bad for doing an experiment at a place where such kinds of experiments are not common.

This afternoon we made the first attempt at in-situ heating our sample. It both worked and didn't work. It worked in that things got hot. It didn't work in that I ended up melting the grounding wire. Without a grounding wire a charge will build up on the sample from the x-rays ionizing the metal atoms. A charged sample is a bad sample, hence the grounding wire.

After some discussion about how best to fix it, we settled on wrapping a small Pt wire around the sample and its pedestal. The wire then connects onto the rotation stage. This took an hour to do and a few more hours to re position the sample from the effort.

Howdy again,

We're back running at the APS doing another set of experiments. This time, however, the experiment is my own baby. We're attempting a different kind diffraction experiment from metal surfaces.

I don't have time to write much. More or less all I can say is that we're extremely busy. This is a rather new kind of an experiment, it's being done with a new chamber, and being done at a beamline where we've never worked before. Top it off with the fact that the beamline isn't optimized for a full diffraction experiment (it is however highly optimized for coherent x-ray scattering!). All together, this is somewhat ambitious.

The experiment began a few days ago in fact. The initial work had to be done in our own lab. It also means that we're going to get one shot at this, maybe two. There is a fair amount of risk involved in that statement. Preparation began with the sample and chamber in the materials science division. Aside from the usual work of preparing a sample (cleaning, degreasing, annealing) and getting equipment together (debugging, writing code, packing, testing), we actually assembled the chamber and its essential elements in our own lab. This included actually getting the sample in the chamber.

Why, might you ask, did we do all this?

In order for this experiment to work, we have to arrive at the beamline with a fully oriented sample. Or at least oriented to within a few degrees. So the whole chamber (sample and all), must be mounted on our diffractometer prior to our APS visit. It must then be removed from MSD and transported intact to the APS. This was not exactly easy. However, we made it.

Here you can see the chamber (the silver ball that has some glowing orange parts)mounted on our diffractometer(the green-blue thing). This allows us to scatter x-rays (from a source off to the right side) through our sample. By correctly positioning the sample and observing where the x-rays are scattered, we can determine the relative position of the crystal sample.




Here's something of a closer look at the inside of the chamber. The crystal is held, inverted on a long quartz pedestal. Yes, it really is held upside down. The erie glow just happens to be the light behind the chamber.