Indexing TEM diffraction patterns from cubic single crystals
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- Опубликовано: 3 окт 2024
- This is the (long overdue) follow-up to the video I created a couple years ago discussing zone axis alignment when performing S/TEM. In this video (as always, filmed raw, unedited, uncensored, and uncut), I cover indexing TEM (parallel beam) diffraction patterns from several common cubic single crystals and answer that all important question: how do I determine the zone axis for the diffraction pattern?
If you did not already see the original video on zone axis alignment when performing S/TEM, I recommend you watch that video first before watching this video: • Zone axis alignment wh...
Thanks for watching! Please like, subscribe, and share and let me know if you have any questions or comments. Video topic requests are always welcome and appreciated; I enjoy making these videos and wish I could make them more frequently, but the demands of my job make it tough to do so; I’m in charge of 3 S/TEMs, 2 dual FIB/SEM systems, and 1 SEM and this keeps me very busy!
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E-mail me directly:
ngr@ufl.edu
Hi everyone: as @DW-iq8lt correctly pointed out, from 11:10 to 20:40 was stuck on slide 3 (I think I had the wrong window selected Zoom); I'm sorry for the confusion and hopefully the audio alone provides enough explanation for when I pick things back up again at slide 10 (and there is a quick look at slide 9 so you can see the 4mm point symmetry I'm referring to regarding cubic crystal B = zone axis families). Unfortunately, things like this sometimes happen when you film raw, unedited, uncensored, and uncut (ha ha).
The key points from the missing slides (all said by me, but not shown): R1 and R2 are the measured distances (e.g., mm or in) of g1 and g2 on the DP. Using the camera equation, it follows that R1/R2 = g1/g2, so it is not necessary to know the actual values of g1 and g2 if the crystal structure is already known. Furthermore, for cubic crystals, g can be calculated in a relative sense as sqrt(h^2+k^2+l^2) independent of the lattice constant, so any g1/g2 depends only on the hkl indices of g1 and g2.
What you have been doing is truly a great contribution to the TEM community. Thank you! I think it's safe to say that you're the mentor to all TEM-related graduate students.
You're very welcome, and thank you for all of your support!
For the last eight to ten years i have not worked for graduate students .......... neither do i intend to work for graduates or any post graduate students ..... this is only a self learning ........tool
Reliable archives of wikipedia !!!
Dear Dr. Nick,
One of the most awaited videos! Thank you so much for your efforts and contributions to the EM community. Once again, many thanks.
Best regards.
Thank you, Deepak.
I was waiting for this video for a very long time. Great video! thanks
You're welcome.
Amazing work! Well done!
Thank you.
Hi everyone: there have been quite a few requests about a tutorial for indexing DPs from hexagonal crystals; I'm on winter break until January 2 so my goal is to get this done over the break. Happy holidays, everyone.
Great video! Would love to see one about polycrystalline samples!
Hi Liam: indexing polycrystalline sample DPs is much easier than indexing single crystal sample DPs since you no longer have the trouble of defining a zone axis. Thanks for the topic suggestion and I'll see what I can do.
Thank you Nick !
You're welcome; glad to see you here on my YT channel.
Great video. Could you maybe make a tutorial on determining the nature of dislocations (e.g., edge vs. screw)?
Dear Dr. Nicholas your lectures are very helpful. Thank you so much. Please can you upload Matlab code which you used in this lecture video?
Glad to hear my videos are helping you! Please send me an email and I will email you back with the MATLAB code.
May I ask the slide which disappear from 11.40 to 20.40?
Hi Leon: yeah, so, this is the unfortunate reality of doing "raw" filming; sometimes things don't go according to plan (ha ha). Anyways, what happened was that I didn't have the right window activated when I was recording in zoom, so the presentation didn't get recorded for those slides as a result. If you email me, I can send you a copy of the slides so you aren't missing anything.
BTW, a few slides you mentioned were not recorded successfully (from 11:10 to 20:40)
Thank you for pointing this out and adding the timestamps; I actually discovered this myself late yesterday when I had a chance to re-watch the video. I added a pinned comment so hopefully this will alleviate some of the confusion.
FFT of HRTEM can be indexed same way?
@qmtv5772 yes, FFTs may be (and often are) indexed and solved exact same way as DPs; this is particularly useful when you are trying to index a DP from an area that is much smaller than your smallest possible selected area aperture; doing HR-TEM or atomic-res STEM and then indexing the FFT becomes more feasible and makes more sense; a deeper dive into FFTs would be a great video topic; thanks again for the comment!
Hello, may i get this Matlab code?
Sure, please send me an email.
you blabber too much, get to the point