I dedicate this post to Dr. Brent Rudyk and Nathaniel O’Coin.
The other day Nathaniel asked me “What is the Canadian Light Source?” He has a friend who was recently doing research at the CLS and didn’t know what it was. His friend was doing near-edge x-ray absorption spectorscopy. I hit a communication block: how do I explain this? I mean, I know what the technique is; I had a number of colleagues while I was in grad school making trips to the CLS and yet I found myself struggling to explain what CLS and near-edge x-ray spectroscopy is. I mentioned it on facebook and my friend, Dr. Rudyk, came back with a GREAT explanation: “CLS is a synchrotron, where highly intense, tunable x-rays are created by bending near light speed electrons. X-ray absorption near-edge spectroscopy (XANES) is the process of promoting a core electron into conduction states and analyzing the resulting “edge-jump” and the general vicinity of the jump.” I was excited. I couldn’t have said it better. I immediately recalled the classes I discussed it in. But here’s the problem: Nathaniel still didn’t quite understand. See he has no chemistry or science background, meaning that the terms “conduction state”, “edge-jump” still didn’t help him understand what was going on.
This whole situation really demonstrates the challenge in communicating science to a non-technical audience. My friend Brent is a wonderful teacher, easy to talk to, and is a great communicator, and yet, his perfect description of XANES and CLS still didn’t help Nathaniel understand. How do we, as scientists, make our explanations more accessible to non-technical audiences without coming off as condescending? This is what the mission of Curiosity Science is all about. I hope that those of you who follow with interest bare with us as we learn to talk about science most accessibly and I hope that other scientists interested in contributing to the project recognise the challenge and the wonderful opportunity that we have.
So with all of this in mind: here is my attempt at explaining the CLS and XANES-really I am just editing Brent’s answer because it really is one of the best explanations I have read. The Canadian Light Source is located at the University of Saskatchewan in Saskatoon, Saskatchewan. It is a synchrotron, which is a source of light generated by accelerating electrons to nearly the speed of light (2.99 x 10^8 m/s) and then bending these electrons using very powerful electro-magnets. As the electrons bend, they emit intense, highly focused beams of light. This light is at different energies: some are x-rays, others are infrared or ultraviolet. These beams that come off allow scientists to do various experiments depending on the wavelength of light.
Different wavelengths of light have different energies. X-ray is much more intense energy than infrared. When an atom absorbes an x-ray, there is enough energy to kick an electron that is closer to the nucleus of an atom to a higher energy state (excited state). These are the core electrons and require a lot more energy to excite or remove compared to electrons located farther away from the nucleus of an atom. The different types of electrons have very specific energies that are required to excite them, this gives rise to the “absorption edge” because in the actual spectrum it looks like a vertical line, like the edge of a cliff. The specific “edges” that one would see in a spectrum are element specific. You can therefore tell what elements are present, what their oxidation state is etc.
So there you go. There is a little bit about the CLS and what you can do with it. The CLS is a pretty cool, state of the art research centre. It is definitely a claim to fame for the University of Saskatchewan and the City of Saskatoon.
Also, Thanks Brent, for helping me in trying to explain XANES to the world. Let me know if I missed something!