Nicely explained. Best lecture ever. We can throw these solid state physics books away that keep talking about Fourier analysis because it is simply not practical.
I agree with you: Clear and concise lecture! By the way, the probability for me to find a comment from a former IFM "colleague" on a youtube lecture video was quite low :) Make steel strong again
Would it be accurate to think of reciprocal lattice points as imaginary apertures which, if passed through by a diffracted X-ray beam, correspond to observed diffraction spots?
Yes - this is absolutely fair. In fact, this is how a TEM works. You can place the detector at 1 position and image the diffraction pattern (i.e., a slice of reciprocal space), or you can position it differently to observe a microscopic image. AND, you can take an actual aperature and block out all your electrons except those passing through a specific diffraction point, and only use those electrons to make the image (this is called SAED, or selected area electron diffraction).
Thanks very much for your vedio. At 10:06, your vocal "2theta angle" in fact means the "theta" angle right? as the angle between incident beam and the plane normal (230) should be 90-theta...
You are exactly right! mis-speak on my part. at 8:30, the angle you're talking about is identified as "theta". So used to thinking about diffraction results, which we usually plot in terms of "2 theta"...
Hi ! This was really clear thanks. I have a question: Why doest the screen detect the constructive interference only when the points intersect the Ewald's sphere ? Satisfaction of Bragg's law is something that happen depending on the structure of the crystal (In terms of phase and plane distance), but constructive interference is something that happen inside the 3D space beyond the crystal right ? How is this phenomenon related to Ewald sphere ? Sorry if i've not been very clear ☺️
Hey great Video! I do not quite understand what is meant with the angle beta it just seems to be in the room and I am also not sure how to determine the direction of the second vector. Is it just the formula of reciprocal vectors?
Beta is the crystallographic angle (i.e., the angle between the two lattice vectors). This *could* be 90 degrees for a rectangular lattice, but does not have to be. We chose beta here because, by convention, the non-90 deg angle in a monoclinic lattice is beta.
