How do Electron Microscopes Work? 🔬🛠🔬 Taking Pictures of Atoms

I still can't believe that this content is available for free, provided the amount of research and hardwork this video would have taken.

I’m a PhD Candidate in Bio-Nanotechnology and I will say that your channel is my favourite. It takes so much effort to understand all those aspects and you are just making seem like it’s simple logic. Lastly the quality of your content is so insanely high that makes me goosebumps.

This is the absolute best TEM and SEM video I have ever seen. I actually worked at Thermo Fisher Scientific on SEMs and dual beams and they never even showed us videos which were this good. Great work and super accurate. Amazing!

Seriously I can't get over how good this content is. The graphical side is perfect, the research and voice over is perfect. Plus the fact that every detail is covered and literally every time you explain something, you answer any question I have immediately after. Everything is covered and thoroughly. I can't believe this is free

This is one of the channels that should be MANDATORY in schools, period. Even those who do not interest in this still can think about it generally and those who want dig deeper and continue to learn deeper math & science to become future scientists.

Electron Microscopes are a rather complicated topic, and we're sure you have many questions. Feel free to ask them, and we will do our best to answer them. Here are some questions from other users. Q: What would it look like to look at an electron beam? [@rage9067] A: The electron beam viewed from a side is invisible to the naked eye. However, it can be observed indirectly, by its interactions with matter. For example, if the beam hits air molecules in the atmosphere, it ionizes them and they glow as they recombine back. In different conditions, these effects are known as glow discharges, electrical arcs and sparks and can generate plasma. If the electron beam hit the retina of your eye directly, it would likely be perceived as a very bright flash followed by local tissue damage and wider-area tissue damage from the generated x-rays. Q: If the electrons pass through the objects, then how is it possible for an image to be created? [@dinev9, @Billyce18] A: At the nanoscopic level, objects are emptier and fuzzier than they appear macroscopically. The electrons passing through atoms usually don’t hit anything directly like billiard balls. But rathe pass through “clouds” of electrical charge from the electron shells bound to the atom nucleus. In doing so, they get deflected by electrical forces from both the nucleus and the electron shells, and deviate from their original direction. That’s how the specimen gets imprinted into the electron beam. Then, more electrons hit one part of the detector and fewer hit the others. That’s how the resulting image contrast gets created. Q: Can we speed up electrons even faster than 70% the speed of light? Would it improve the images? [@kusura43] A: Yes we can. The most common speeds correspond to kinetic energies of 100-300 keV, so 55-78% the speed of light. Higher energies for imaging are rare, as they generate a very large number of x-rays that need to be shielded, require stronger magnetic fields for focusing and generally bring only very little improvement in terms of image clarity or resolution. Historically, there were experimental microscopes with electron beams of up to 2 MeV (2 000 keV), so 98% the speed of light, but they were as big as a building and generally not worth the trouble and costs in terms of performance. Q: Who was the first person to build an electron microscope? [@MrSimonw58] A: German physicists and engineers Ernst Ruska and Max Knoll. There’s a bit more info on the history in the Creator’s comments (English/Canadian subtitles) now. Q: Couldn’t AI clear up or upscale the image? [@user-if1ly5sn5f] A: Yes, to a degree. A fair amount of image processing techniques, both classical and AI-based, can be used to “improve” the raw images. However, you typically need more images from the same area of interest under slightly different conditions, to make sure you’re getting additional real information. Instead of artifacts of the used method. For radiation-sensitive specimens, this may be a problem as each additional image changes and degrades the selected area of the specimen. Q: Can anything be imaged by an electron microscope? Are there any induction effects like eddy currents or atom bond-breaking in a 100 nm thick specimen (e.g. from metal)? [@ramit_arko] A: In general, yes, any thin enough specimen can be imaged with an electron microscope. However, some are radiation-sensitive (typically biological specimens) and they quickly degrade under electron illumination. Their atomic bonds indeed break. Another interesting category is magnetic samples – these require the objective to be turned off in a special mode, so that its magnetic field doesn’t influence and change the domains in the specimen. This results in lower resolution and magnifications. The eddy currents are not a problem for two reasons: First, the electron beam is typically stationary, not pulsed, so the no electromagnetic induction takes place in the specimen. Second, the specimen is so thin that these currents are suppressed even in the rare case of pulsed-beam operation. Q: Can the cameras give us a live feed one day, to not only take images, but also videos? [@-Nuke-] A: They absolutely can, even now! Depending on camera type and its resolution, you can take videos with a framerate ranging from a few tens of frames per second, up to several hundred! In order to look at even quicker events, you need specialized detectors and pulsed beam operation, typically achieved in combination with femtosecond lasers or other techniques. These can give amazing resolution not only in space, but also in time. There’s a bit more on that in the Creator’s comments (English/Canadian subtitles) now. Q: Is there some way to “invert” the image contrast by directly manipulating the electrons? Also, how do you focus electrons with a hole (aperture)? Are the apertures made of specially compressed material, so that they can stop the electrons? [@orrotem7860] A: The electrons in the beam are affected not only by the specimen, but also all the optical elements in the column – lenses, apertures, deflectors, correctors, imperfections and disturbances etc. They together make up what’s known as optical transfer function, or more specifically contrast transfer function. This is what describes the “inversions” and also blurriness and other effects in image contrast on objects (like atoms or clumps of material) of certain sizes. There are some ways to counter these effects by directly manipulating the electrons, one of them being the use of phase plates. As for the other questions, the holes (apertures) are not used for focusing, but mostly filtering. Either of image spatial frequencies carried by electrons far from the optical axis, or of stray electrons scattered by something else than the specimen. The material of the apertures – typically gold, platinum or other dense metals – does not have any special treatment. It’s just thicker, so it stops even the high-energy electrons. A bit more on both these topics is in the Creator’s comments (English/Canadian subtitles) now. Q: Can we combine a particle accelerator and an electron microscope to image using quarks (or other particles) for even higher resolution and magnifications? [@user-cz9jf1ec8s] A: There would be a lot of impracticalities for such approach. Quarks, as far as I know, cannot exist as individual particles at common energies, but only in bound states: either quark-antiquark pairs (mesons) or in trios (baryons) like protons or neutrons. These composite particles are very heavy, making them significantly more damaging to the specimen. So even though they would have a smaller wavelength than electrons at comparable energies, their larger momentum and interaction cross-section would destroy the specimen (and likely also the camera) very quickly. If we go the other way, to lighter particles, there’s not much else either: Neutrinos lack electric charge and almost don’t interact with regular matter. Light with very short wavelengths (typically x-rays) is used for imaging, but difficult to focus or optically control, and requires a lot of shielding for safety. Plus, typically fairly large (building-sized) synchrotron sources. Taking all this into account, electrons are actually pretty good particles for imaging the nanoworld, all things considered. It seems more practical to work on optical aberration correctors for electrons if we want to reach higher resolution and magnification, rather than to look for a different carrier particle. Q: How is the 50 000x zoom of the projector lenses achieved? [@krissn8111] A: It is just the cumulative effect of 4 lenses gradually magnifying the image created by the objective lens. The total magnification is the product (so, multiplication) of the individual lenses’ magnifications. Q: How is it possible that the specimen holder material does not interfere with the scanning? [@JuanCruzAvila] A: The specimen is usually placed on a thin carbon foil, either continuous or with holes, supported by a thicker copper grid. Alternatively, it can be welded (using micromanipulators and a focused ion beam) to a different kind of grid. These grids are then placed in holders and inserted into the microscope. In almost all cases, the scanned area is much smaller than the support grid “windows” or “fins”, so there is no interference in the scanning process from the grid or the holder. Q: Is the tungsten crystal a serviceable item? As in do you need to replace it after a certain amount of uses? [@timster150100] A: It depends on the type of the electron source. The oldest, thermionic sources (not shown in the video) used a tungsten wire (similar to that of old lightbulbs) that had to be exchanged every several tens to a few hundreds of hours of use. The Schottky (i.e. heated) field emission sources last for thousands of hours before needing replacement. The Cold field emission sources can last tens of thousands of hours. But it depends on the conditions under which they are used, typically the vacuum quality and the amount of heating. Q: If we had unlimited money how much higher could the resolution be with our current tools and knowledge? [@hexramdass2644] A: What an interesting question! If I had to speculate, with unlimited money and brainpower, I’d say we’d be able to reach close to the diffraction limit of several picometers in a single image. Even now, one exotic indirect methods combining a large number of images and iterations (electron ptychography) was able to reach a reconstructed image with a resolution of around 20 pm.

As a 3D artist I must appreciate the amount of work went into this video. Granted that sponsors were generous and shared rough 3D models.. still those models must be technical oriented (CAD exports that require a ton of cleanup) Someone must have gone through the geometry clean-up, UVs and texturing to make them look accurate AND visually appealing. Props to the Artists, narrator and rest of the production team 🙌🙌

This is sponsorship done beautifully! One of the only videos I've ever seen where the sponsor adds real value to the content, while also being completely relevant to the subject. Thank you to the video creators for choosing content value over money, and thank you to the sponsor for contributing to making this video so much more informative!

Always have to love a reference to the powerhouse of the cell.

As someone who works for Thermo Fisher and makes these incredible machines I'm really satisfied by your explanation of how it works. Fun fact: 3 companies based in Brno city are responsible for almost 1/3 of global production of electron microscopes, that's why Brno is called "City of electron microscopy".

9:25 I've officially learned how aperture is used in photography. I knew the simple things about aperture and how it effect photos, but after seeing this visualization, I fully understand now. Heck even my entire perspective on how my eyes receive light has changed. Thank you.

The amount of research and hard work put into the research and 3D animations is simply astounding. Very clear and thorough explanation, guy! Keep up the amazing work!

I've been doing TEM for years and this is one of the best videos I've seen on the topic. The animations in particular are fantastic. Looking forward to the creator comments!

Hands down best channel on YouTube

Outstanding as always. This is likely my favourite channel on YouTube. Never fail to deliver complex topics with incredible graphics and excellent descriptions.

I asked a few teachers and professors, but no one could explain it like this crazy, detailed video. Thank you

There are only handful of YouTube channels I eagerly wait to put out new videos. Branch Education is definitely one of them. Quality content as always with something new to learn everytime.

you guys are incredible!

I'll be completely Honest, at first, I was really sus of all the comments praising this video for just about every reason, and thought it was bots . . . but then I watched it and realized it was no exaggeration . . . then I get halfway through the video and they drop the fact that there's even MORE information in Canadian subtitles and now I'm on my 3rd rewatch of the video taking detailed notes. This video is an absolutely amazing piece of content, and has really helped me prepare for my SEM training.

I'm very very happy you got such a lab equipment sponsor like Thermo Fischer. You guys really deserve it from such an amazing quality content!!