Scanning Electron Microscopy (SEM) Lecture: Principles, Techniques & Applications

[@AsmaAttariabad]

Great lecture with a lot of information

[@zombiemaniac_3955]

Great video. I am in High school and have have been restoring an old SEM from the 1980s, so this has been very helpful in teaching me the general concepts. Thanks!

[@julius4026]

Great lecture. This summarizes pretty well a 4month course on electron microscopy. One could easily spend 1 week talking about vacuum systems, 1 week on electron guns, 2 weeks on electron-matter interaction, etc.. SEM is a very complex tool-system involving a lot of fundamental physics as well as top engineering... the effort and clarity put in this lecture is awesome. Thanks.

[@raoul__duke]

This lecture is a masterpiece, finally I understood all the detailes about SEM principles I needed. I am sure I will get much better images after getting this knowledge. Thanks a lot, Dr. Hunt!

[@sonyporter]

Excellent lecture, this is the first step for the freshman who is going to understand EM.

[@jacobhudis2024]

Great job! I am sure this has helped a lot of people, I know it helped me!

[@ahsanulkabirsumon2249]

Great lecture in detail. Thank you very much for keeping it open source.

[@RaiNivesh]

Very well illustrated. One of the best lectures on the topic out there!

[@nuray4717]

great lecture i listened every second of it carefully.thanks for sharing this awesome explanation video, you made my day.

[@anastasiyahamdi7524]

Great lecture! Beautifully summarized. Fantastic Lecturer!

[@ravanansathesh]

Very detailed lecture..Really helpful &Thanks for the slides..

[@DrMeowScience]

This is excellent!! Thanks so much for sharing your knowledge!! Very informative and helpful resources from the specialist!

[@aliansarihamedani8057]

A very nice lecture. Good luck

[@gcr100]

a total masterclass thank you for posting ths

[@sheralishanu9657]

excellent explanation ,,,,, Thank you.

[@Scott21]

Thank you for making this!!!

[@radhakrishna.kalluri7192]

Great lecture....

[@ChenTyler-i5m]

Excellent lecture

[@user-zv6wm8yl7v]

I thank you very much. I loved my specialist after hearing your lecture

[@dahcari6548]

Hi The Kavli Nanoscience Institlute at Caltech, I have question about your video 1/ Could SEM see nano materials, clearly or blur ? (I mean it's a normal SEM, not FE-SEM or high resolution SEM). 2/ Which is the best method, cheap and convenience for characterizing (shape and size) nano materials? I hope I would receice your answer soon. Thanks The Kavli Nanoscience Institlute at Caltech so much.

[@janusaher7615]

VERY GOOD

[@Heroofutopia]

Thank you

[@arupghoshal5814]

The fesem machine stops running due to the lockdown period. And the electron gun is turned off for 10 months. After starting now it seen that the emission current is changing fast. before lockdown it was around 38microampere at 15kv. Now it's 15.8 microampere at 15kv. Yesterday we start running the machine. Want to know the cause of the emission current decrease. Please help

[@hyunsulim188]

I think gun tip is bended.. because machine was turned off too long so gun tip cool downed and it makes permanent deformation of tip shape. If possible, try to increase the extractor voltage.. It could be a temporary solution..

[@andymouse]

@@hyunsulim188 Could be the only option but it is a last resort !

[@nooryaseen9388]

If I want to assess the structure of cement concrete, I will have to dehydrate the samples, which indicates that I am going to visualize the structure without the important hydration products such as CSH (calcium silicate hydrate) and CH (calcium hydroxide). Don't you think it does not portray a good message in the field of concrete or cement? (Nevertheless, if you search about SEM of cement- or concrete-based samples, you will come across a myriad of papers incorporating SEM testing of these products.)

[@matthewhunt1674]

You could use what's called an Environmental SEM (ESEM), which uses a backing pressure of water vapor in the chamber and should prevent the sample from drying out and the morphology from changing. I talk about this at this point in the video (kzbin.info/www/bejne/kJmVYqemaMaDe9k) and you can find more information on this technique online elsewhere

[@felixkorolev284]

very cool

[@scriewy]

look look all at the phenomenon, on most "common people" youtube videos you always get 10-20% thumbs down no matter if it's 1000 votes or 300,000, but here it's totally skewed. only 1.42% thumbs down, means 98.58% of all viewers of this video are not normal people.

[@samuellin9217]

Lol

[@hailfire27]

Lecture is too detailed. Does not describe fundamentals that well. Need to show the purpose of each component.

[@preciousamaechi689]

Your comment doesn’t seem to make sense. If the lecture is too detailed, how then did it not describe fundamentals well? What then was the “too detailed” doing while ignoring detailing out fundamentals and purpose of each component?

[@andymouse]

"Lecture is to detailed" what a laugh ! that means it's a level to high for you just drop down a few chapters where they will use crayons.

[@MarySmith-gu5nb]

Your lecture is not clear. For example, when you refer to coating the tungsten coil with zirconium oxide to further increase the emitted ions from the tungsten tip, you simply say "That allows us to increase the ions from the tungsten tip" when it would have been more informative to say how it does that. Why zirconium oxide? Who figured that out? When you refer to the condenser lenses you say "Allow us to demagnify the electron beam" but you never explain or clarify that statement. Much of what you say is like this ---- not explanatory, only internally repetitive.

[@sollinw]

but my book is also like this pretty much, quite frustrating. maybe it's not ceven clear for the brightest of us

[@matthewhunt1674]

Yeah, I'm sorry if it's not entirely clear. I was trying to keep all of this material in a one-hour lecture so couldn't explain every mechanism in detail. The ZrO2 lowers the work function of the tip, which makes it easier for electrons to escape the surface, leading to more electron emission. Over time, the ZrO2 evaporates from the tip (the tip is very hot, as this is field-assisted thermionic emission) and so you run out of ZrO2 and need to replace the tip eventually (it also mechanically drifts/deforms, necessitating a change). Now, that's how it has been explained to me. Curiously, though, the electron emission tends to *increase* as the FEG tip ages so there must be some other mechanism underpinning the change in overall emission... or maybe it's just that the emission profile changes (more emission overall, but not from an optimally small area of the tip, leading to a larger virtual source, and a need to change). I've actually never been entirely clear on this myself. This would be a good question for people at Zeiss, JEOL, Hitachi, Thermo Fisher, etc who have developed these FEG sources. I'm sure there are also papers on this from decades ago that could be studied. As for the demagnification via the condenser lenses, this needs to be investigated with equations in optics (not necessarily electron optics, just lens optics in general). There is some treatment on this in the SEM book that I like to use (www.springer.com/gp/book/9781493966745) though it's not super rigorous. If you've seen the equation "1/f = 1/p + 1/q," that is at the heart of this, where magnification, M = q/p, and demagnification, m = p/q. You have to study ray diagrams to understand how this all works out mathematically, but can be done and you could readily find resources on this online just by googling things like "magnification equation optics." I applaud you for wanting deeper explanations. They are out there if you want to dig, I assure you!

[@andymouse]

Ungrateful person, isn't it obvious we are talking about the 'work function'