Zone axis alignment when performing S/TEM
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- เผยแพร่เมื่อ 10 ธ.ค. 2024
- When doing any type of high-resolution imaging of a large single crystal specimen, you will always get the most detail in your images by aligning the sample along a major crystallographic zone axis; but what is a zone axis and how do we align to it when performing S/TEM?
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 beam FIB/SEM systems, and 1 SEM and this keeps me very busy!
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ngr@ufl.edu - วิทยาศาสตร์และเทคโนโลยี
Gosh! This video is so helpful! I'm so grateful for the simplicity and you're so on point! Thank you!
Glad to hear my video was helpful to you; thank you very much for your support.
You save me really！I felt quiet confused about this topic across the whole semester . I got it in your video. Thanks again.
You're welcome, I'm glad you found the video useful!
Very good narration and explanation. Good Job. Thanks -Premkumar , India
You're welcome!
Hi everyone:
I uploaded a (long overdue) video tutorial on indexing TEM diffraction patterns from cubic single crystals (as many of you have requested); you can find it here:
th-cam.com/video/8dPL72GGQRk/w-d-xo.html
Thanks Nicholas, this video is very useful analyze materials using TEM, please show lot's of video like this in series.
Thanks for your support! I will continue to make videos as long as people are interested!
Good explanation sir, thank you very much!!
You're welcome.
Thank you Nicholas, your videos are very helpful!
Hi Duaa: you're welcome, glad you find the videos helpful.
It was a tiny video but very powerful. I understood two things; I realized the effect of having in zone axis on the HR imaging and secondly, the iterative process of obtaining it. I have some queries; i) How Kikuchi pattern is being used to align to zone axis?, ii) When you have nanoparticle sample where each particle has its own arrangement then how to effectively deal with multiple fixing of zone axis for each? Finally, thank you very much for providing this information. With this, I can have better quality results coming out of my hands.
You can also use Kikuchi lines to assist with zone axis alignment (this is actually a good topic for another video) but if your sample is very thin there won't be any Kikuchi lines. If you have nanoparticles, then you can align along a zone axis for an individual particle (which is very challenging if the particle is very small) but you wouldn't be able to get multiple particles aligned at the same time since they are usually randomly oriented. The usual practice when imaging nanoparticle samples is to simply search around until you find ones that are giving nice lattice fringes, rather than trying to manually align to a zone axis for a single particle (though it is possible to do this if you are careful and patient).
@@NicholasRudawski thank you for sharing
@@urwashigupta3142 You're welcome
You can have experimental kikuchi maps in which you can identify poles and once you coincide your 000 spot with a pole in kikuchi map, then your ZA orientation corresponds to the indices of the pole.
Dear Nicholas, Thank you very much. Your videos are very informative and useful.
You're welcome, glad you find the videos useful!
Thank you so much for your wonderful videos.
You're welcome.
Thank you very much for a clear explanation, I would like to know how I can I use apply this to FFT pattern.
You're welcome! It is a little more difficult to use the FFT to assist with zone axis alignment, though you can indeed see changes in the FFT as the zone axis alignment changes. The issue with the FFT is that opposite spots will always have the same intensity, regardless of how close the alignment is to the zone axis, so this is much less helpful compared to the DP. That being said, the spots will become more intense and you will see more spots farther away from the center of the FFT as the zone axis alignment improves, so these also indicate the precision of the alignment. If you compute the FFTs of the two HR-TEM images of Si that I showed, you will see this (actually, this would be good to post as a video).
thank you very much. it would be very nice to see such a video (simple explanations as this is and step by step procedure ) with comparison and highlights in similarities and differences between DP and FFT. also how to determine zone axis from FFT. and also not only cubic phase where the rings are relatively easy, but some other structures as well. thanks again.
I appreciate your effort , very useful
Hi Anamika: you're welcome; thanks for stopping by to watch and glad you find the videos useful.
Thank you for the nice videos! do you plan to upload a cross-sectional TEM imaging?
Great video, thank you
You're very welcome!
Great. Many thanks for this.
Very informative! Would you also please teach the alignment of STEM, especially how to get the Ronchigram image?
Hi Biva: glad the video was helpful for you. Please see this video about STEM alignment using the Rochigram:
th-cam.com/video/oZ45seme5cA/w-d-xo.html
Hi Nicholas, many thanks! I found that.
@@bivatalukdar8143 You're welcome.
Excellent video, I understood very well what it is a zone axis, why it is important to obtain good quality high resolution images and how the alignment of the zone axis is carried out. However, since I am new to this field, I am trying to relate it to Bragg's law and I cannot relate it, since if the beam is parallel to all those planes that are in the zone axis, there would be no diffraction; those planes will not produce diffraction. My question is how the diffraction is generated in all those parallel planes with the beam?
Beam is parallel to the zone axis direction but diffraction occurs because of the interference where the atoms in the planes behave as the slit... So even if they are parallel to a particular direction but still there are atoms behaving as slit...
Thank you so much, your video was very informative. I have one question, how did you decide that its 110 alignment to the ZA? why not another like 11-2 or etc. Please write some words about this?
You're welcome, and sorry for the late response! I know the ZA = from experience from working with this material (and zone axis) so extensively for so many years, so it's a bit of hand waiving on my part here. If I didn't know this, I would need to solve it by indexing (solving) the diffraction pattern by hand. Solving single crystal diffraction patterns is definitely something that I could dedicate a whole video on (and others besides you have also asked about this, too). Hopefully, I will get to this at some point in the near future!
Thank you so much for the video series! I have questions about the alighments, could you introduce us in detail, how to align a TEM to a good stand?
Hi Season; I'm not exactly sure what you mean by align to a "good stand"; could you please elaborate on this?
@@NicholasRudawski Thanks for your reply! I am a rookie on TEM and right now I have so many problems in alignments. For example, how can I confirm, ob the sample is overfocus or underfocus? And do we need to iterate the alignment procedure? Becauseat first align the gun tilt, but the Pvot is not correct. And after we align the Pvot, do we need to reverse back and correct gun tilt again? Thanks again!
@@seasonzhang2985 I suggest looking through the first video I posted about general operation; your question about over/underfocus is a good one and actually gives me an idea for a future video
Thanks. This helps my thesis. May I get the textbook about zone axis alignment you metioned?
Hi Fan: you're welcome; please see here for information about the textbook:
doi.org/10.1017/CBO9780511615092
Thank you so much for the useful video.
Do you have any tricks to find the zone axis you really want? For example, when I go to the diffraction mode, I see a kikuchi pole, go to it very easily and find it to be [112] in fcc, but what I really want is [110]. So how can I decide which direction I should go further and how big the step should be? Could you please share some experience? Thank you very much!
Hi Xingpu; I'm glad you found the video useful! Generally speaking, when you are working with a single crystal specimen, you prepare the specimen for imaging along a specific zone axis. If you want to image along a different zone axis in the same sample, this can be tough do depending on tilting limitations; your best course of action may be to just make a new sample prepared for viewing along a different zone axis. If you are working with a polycrystalline sample, things get even tougher because you likely don't have any idea about which zone axis you are close to for a particular grain before you make the sample unless you do something like EBSD beforehand. If you are finding the [112] zone axis but want to tilt to the [110], the two zones share a common 2-20/2-20 Kikuchi band pair so you would need to identify that band and follow it (tilt) to get from one zone axis to another. That said, the angle between [112] and [110] is about 55 degrees, which is pushing tilt limits of most TEMs.
Thank you very much for your valuable videos!. Can you make a video on nanobeam diffraction, please?
You're welcome; please look for the video on my channel about CBED.
Hi! I just want to ask, for the case of single crystalline sample, how many zone axis should be checked during the TEM analysis? And should I expect different planes on the different SAED patterns obtained at different zone axis? Thank you!
Hi Jeanne: I'm very sorry I didn't see this until now. As far as how many zone axes to check, it depends on what you are trying to do with the sample. With a single crystal, you are usually only concerned with the zone axis that is aligned with the electron transparent direction of your sample. Usually, you prepare the sample to target a specific zone axis. You are correct that if you tilt to other zone axes you will most certainly encounter other sets of planes, though it is possible (even likely) that there are some common planes between two different zone axes.
Nice video! Could you explain more specially the zone axis allignment process. I have tried to allign the zone axis, but I am still not sure the direction of the ± alpha tilt and ± bata tilt. And is it better to do the alpha tilt firstly?
Thank you! How you need to tilt (alpha versus beta, negative versus positive) based on the appearance of the diffraction pattern to align to the zone axis varies from instrument to instrument, but for all instruments it is possible to figure this out a create a diagram so you know what to do. This would actually be a good thing to post as a short video: how to make a "zone axis tilting guide".
Just a reminder for this short video...
Nicholas...
"Tilting Guide"
Please make the video for tilting guide
Hi Nicholas, Thanks for your very informative videos. I am still little doubtful that how do we label the zone axis like [110] etc?
Hi Sourav: I'm glad you find the videos informative. Your question about how to assign indices is related to the broader topic of indexing single crystal diffraction patterns. This would be a great topic for a future video. In the case of Si, using [110] is partially arbitrary, as I could use any equivalent direction, like [101], [011], [1-10], etc. and still be correct due the inherent symmetry of the material.
A simple way to identify ZA is to index the diffraction spots and take the cross product of any to indices and that will give you ZA.
Thank you for your videos.
What is the tilt range of alpha for single tilt holder? Can I tilt Beta when using single tilt holder?
Hi Sara: this was actually an important detail that I somehow left out of the video; you need a double tilt holder to use the beta tilt, so it's practically impossible to perform zone axis alignment with a single tilt holder; the alpha tilt range on our Tecnai with the S-TWIN lens is +/- 60 degrees; the beta tilt range is +/- 30 degrees; depending on the lens type, these values can be different.
Thank you. Would you be able to make a video about sample preparation by FIB?
@@saraa2636 I definitely plan on it; I just uploaded a video about operating our FIB, so that will be the "prequel" to the lamella prep video!
Can you please tell me how can I know the zone axis of the crystal from the given diffraction pattern and indexing diffraction pattern? I read more about this point and I can't understand it ?
Hi Mostafa: what you are describing is called "indexing" (or solving) the diffraction pattern. When you do this, you figure out the zone axis of the pattern and the indices for each of the spots. This is definitely a topic that deserves a video to discuss it properly, and I hope to do this eventually.
Thanks
How to calculate ZA from diffraction pattern
Hi Chinnam: to figure out the ZA, you need to index the pattern; a simple answer, but can be more complicated in practice; a "how-to" video on diffraction pattern indexing is definitely on my to-do list, so please be on the look out for that.
A simple way to identify ZA is to index the diffraction spots and take the cross product of any two indices and that will give you ZA.