Kathleen Lonsdale and why the material is named after her

13:15named after Dame Kathleen Lonsdale. She was a foundational X-ray crystallographer and prison reform advocate. Very very cool person, okay? She pioneered the use of X-ray crystallography. She actually did her PhD under William Henry Bragg, the dad. >> Yeah. >> Okay? And um she wanted to understand the structure of aromatic compounds. Specifically, she figured out that benzene, which is um a six-carbon ring with six hydrogens, that thing is a flat ring. >> Mhm. >> She figured out that the structure of that thing was flat. She's one of the first to actually use something called Fourier transforms, which is where you go from frequency space to

13:55position space. The real mathematics behind X-ray crystallography, she's the one first one to figure out how to quantitatively use the mathematical theory to understand even more complicated patterns with X-ray crystallography, okay? And so she laid the foundations of, for example, later on when X-ray crystallography was being used for proteins and other kinds of really weird amorphous solids or DNA, the famous DNA picture that Rosalind Franklin took of the X-ray crystallography with the X. >> Yes. >> Her theories are what laid the foundation for that kind of work. To be like, what is the kind of molecule that would give me an X? >> Yep. >> And uh Francis Crick was the one who figured out, okay, it's got to be a

14:36spiral. >> Right. >> Right? And the the spacing of the DNA of the the spacing of the dots on that photo tell you how far away nucleotides are in DNA and how far away the turn is on a helix and things like that. So incredible individual, she's one of the first to first two women elected to the Royal Society. Um she was also a Quaker, which is like you know, it's the religion that Benjamin Franklin is famous for in Pennsylvania and things like that. So she refused to register for civil defense duties during World War because they're very non- >> Yes. >> violent people, right? >> Yes. >> Um and she was in prison for a month and her experience in that prison was like she used that experience to become a

15:17passionate prison reform advocate. >> Right. >> So >> Yes. >> Yes. >> All over the place she was. Great scientific impact, great social impact, not only by being a pioneer as a woman at the time who were not allowed in these scientific spaces as a generalization, but also still being grounded to that the world is still society and it's not just the work we do in a lab. >> Exactly. Yeah, so incredible woman. This paper that comes out in 1967 by Marvin, they claim to have found the hexagonal diamond. They named it after Dame Kathleen Lonsdale. They call it

15:58Lonsdaleite. They did x-ray diffraction on this thing and they showed that it has the same pattern as something called wurtzite, which is a zinc sulfur mineral that has hexagonal symmetry. Here what you're looking at is an animation of wurtzite. Just imagine instead of the two different colors, which are zinc and sulfur, all of them are the same color cuz they're all carbon atoms. That's where all the carbon atoms would be. There's two things that are different about this compared to the cubic diamond, okay? First thing obviously is look at the unit cell. It's a hexagonal prism. Right? There's a hexagon um face on the top and the bottom. And the other thing is you're actually packing the carbon atoms closer together

16:40because the tetrahedral