One of the fun things is when science ends up (inadvertently in this case) looking like art.

It has become necessary to my upcoming experiment to simulate what our scattering patterns might look like. Below is the result :




It's the kind of picture I want to make in higher quality and then print up on giant poster sized paper.

It's not exactly what we'll see when we do our experiments, but it's something similar. In fact, the pattern is calculated in a geometry that we'll never observe (ie orientation of the crystal, beam, detector, etc), but I find it a rather striking pattern. The pattern is representative of scattering light (x-rays) through a monolayer of gold atoms. In this case, the atoms are arrange in a hexagonal pattern as you would find on top of a cubicly cut gold crystal. Instead of remaining in the cubic arrangement the atoms "reconstruct" into hexagonal patterns. Now... if you've ever tried to lay down a hexagon on top of a square, you may have noticed that there is no unique way to place the hexagon. There are two possible and equivalent ways to lay down the hexagonals. Nature is aware of this and so we end up with hexagonal arrays of atoms that are oriented 90 degrees away from each other.

What this means in the scattering pattern above, is that instead of just a single array of 6 hexagonal peaks in reciprocal space we instead find a total of 12 peaks, or two arrays rotated 90 degrees (or equivalently 30 degrees) from each other. The central bright region is from the unscattered light and the scattering due to the large scale structure of the pattern. The first set of higher ordered hexagonal peaks is also visible around the bright set of 12. Also visible is some "random" variation and faint signals. This noise is, in this case, due to the random shapes of the hexagonal domains I used (the atoms are still arrayed in hexagons, just the larger shape made by all the hexagons is a little random.