Question: what graph were you doing and what was it for

Jonny Brooks-Bartlett answered on 13 Jun 2015:

You can see the plot here: https://github.com/JonnyCBB/StructureFactorCorrelations/blob/master/test/reflectionplot12_hkl-0-2-0.pdf

Basically I work with crystals that contain proteins and when you shoot them with X-rays they give spotty patterns called diffraction patterns. I was creating a plot too show how the different atoms contribute to how intense the spot is on the diffraction pattern. The big red arrow in the image is related to how intense the spot is. All of the other atoms add together from end to tip and end at the same place as the big read arrow. You can also see that the arrows for the different atoms are different sizes because some have more electrons then others (sulphur – orange arrows – has the biggest single contribution). The number of electrons determines how intense the spot is.

I hope that helps a little bit with understanding what the graph means.

The reason I’m doing this is because I want to see what changes occur to how intense the spot is if I decide to move some of the atoms in the crystal. This graph helps me visualise what changes that I see.
I hope one day to be able to predict how the intensity changes and then correct the changes when atoms move due to the X-ray damage.