PS157 Research Project on the topic of Laue Diffraction

3.10.2020

As part of our PS157 Physics Laboratory II module we are given a project that we must research, carry out any necessary experiments before finally giving a presentation on what we learned, how the experiment went and any of the information we obtained from our experiments. Me and my lab partner were given the topic of Laue Diffraction to research as well as to try and replicate. Although the experiment and presentation part of the project didn't go ahead due to colleges being closed down, we still managed to do a large portion of research needed to begin our project and I thought it would be a good idea to at least include that part of the project in a blog post.

One of the first questions we had when undertaking this project was 'What even is Laue Diffraction', to which we found a pretty satisfactory answer, as well as some good visual representations through google. Laue Diffraction is essentially the result that happens when you point an incident beam of radiation at a substance with a photographic film behind it, the substance which is being bombarded gives off a pattern which then appears on the photographic screen behind it, this pattern can then be used to determine characteristics about the material in question.

One of our first tasks for the research project was to come up with a simple simulation of this Laue Diffraction, before we even got to work with radiation and photographic film we were expected to use general items found in a physics lab to represent the theory behind the experiment. Our research supervisor Dr. Henry Barry was able to point us in the direction of an article published in 'The Physics Teacher' titled 'Optical Simulation of Debeye-Scherrer Crystal Diffraction', This article essentially described two researchers who had successfully attempted to do the exact Optical simulation in an inexpensive way. Instead of using a source which produced radiation we would instead use a visible laser beam and instead of a sample material we would use a crushed up diffraction grating, this way if we placed an ordinary screen behind the crushed diffraction grating and let the laser light shine through we would get a pattern that would be reminiscent of what you would expect to see in Laue Diffraction.

As well as coming up with ideas for an optical simulation that could replicate the experiment, research had also begun on fun facts about Laue Diffraction which could make our presentation way more engaging, as well as potentially giving some insight into what we should expect from our results. Since we were never able to give the actual presentation, I thought it would be good to list some of the interesting things we found.

1) Laue Diffraction is named after German physicist Max von Laue who received the Nobel Prize in Physics in 1914 for his discovery of the diffraction of X-rays by crystals.

2) A famous female Irish chemist Kathleen Lonsdale was mostly known for her work on X-ray crystallography and Laue Diffraction, she's also the chemist who the Lonsdale building in DCU is named after. She was also the first female Professor at the University College London.

3) Laue Diffraction also comes with a set of equations known as 'Laue equations' which describe the scattering of waves at a lattice.

4) There are actually many methods of carrying out Laue Diffraction, there is a Rotating crystal method, a Laue method, Back reflection method, Transmission Laue method and a powder method.

5) In 1935 the German government prohibited its citizens from recieving or keeping any Nobel Prize after a German journalist who heavily critiqued the nazi party won a Nobel Peace Prize that year. Max von Laue sent his Nobel Prize to Niels Bohr's Institute of Theoretical Physics in Copenhagen so he didn't lose it.

If you're interested in seeing any more of the research we did into this project, you can read the 1 page progress report we submitted under the Lab Reports heading, or you can read this 12 page document we created where we haphazardly included information we had found online as well as summaries of some of the concepts we would be exploring in detail.