The Physicist Who Unveiled Crystal Structure With X-Rays

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Rational Thinker

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@acebharath 4 ай бұрын

This channel is criminally underrated.

@KwK-c7t 4 ай бұрын

I'm a criminally undereducated person (F'd up school) happy to be an autodidact watching this for free. You are right 👍

@hepiik.8822 4 ай бұрын

9.3k subs now Leaving it here so I can go back in few months for comparison. This channel is awesome, keep it up!

@InductorMan 4 ай бұрын

Nice summary! A technical point and a historic point: the anode of an x-ray tube doesn't need to be heated to radiate; the radiation is caused by the deflection of the electron trajectories as they interact with nuclear charges (bremsstrahlung) and by orbital electrons falling into core electron vacancies in the atoms created as the incident electrons ionize atoms (characteristic x-rays). Although the anode sure does get hot! Also, that's a cold cathode x-ray tube. The hot cathode (Coolidge) tube was invented 1913. Cold cathode tubes were apparently a pain to operate: they depended on a low and very specific internal gas pressure for operation, yet operation of the tube tended to "harden" the vacuum by reducing the gas pressure (through sputter-pumping from cathode sputtering, etc) and render the tubes nonconductive. The solution was to put some sort of gas-emitting or gas-generating material in a side arm of the tube which could be heated by a current which flowed only when the tube voltage rose to excessive levels as the conductivity dropped. That's the weird T-shaped thing sticking off the side here. Not sure exactly what material they used, but pretty much anything off-gasses if heated in a vacuum. I think I've read that some used a dead-end metal capillary tube sticking into an auxiliary chamber filled with hydrogen (many metals allow hydrogen to diffuse through them easily when heated very hot). Now, normally one of the wires connected to this auxiliary circuit was bent to form an air spark gap with another wire connected either to the anode or cathode circuit, and the operator would adjust the operating voltage of the tube by adjusting this gap. When adjusted wider, the tube conductivity would drop lower and a higher tube voltage and harder (shorter wavelength) X-rays would result before the auxiliary circuit conducted by sparks to that wire and introduced more gas. When adjusted shorter, the air gap sparked more easily and the tube operated at a lower voltage and produced softer x-rays. I don't see a spark gap at all on this tube's side arm circuit so I'm actually not 100% certain how the gas pressure/voltage regulation works here. It's possible that the bottom wire from the side arm is the spark gap wire and just happens to be adjusted to touch/short to the cathode terminal (that wouldn't be a bad safety measure while the tube was idle!). Or maybe it's a different type of regulating apparatus. Also btw I think the top electrode terminal is probably the one associated with the anode. I'm not sure that I'm totally understanding what I'm seeing: but the top terminal sure looks like it has a heat sink on it and the thick stem appears like something you'd want to conduct heat... although the design of the heat sink looks awfully modern for a pre-1912 anything, so maybe I'm wrong about that. [edit: the Crookes Tube section in the "X-ray tube" wikipedia article has a nice explanation, and actually it looks like that is indeed the anode heat sink on the top]

@RationalThinker118 4 ай бұрын

Great info, thank you, especially for correcting the snippet about how the x-rays are actually produced through braking radiation!

@williamogilvie6909 4 ай бұрын

Very well presented! In 1979, while working for a company that manufactured FTIR spectrometers, I put a piece of opal in the sample compartment of a spectrometer and acquired the NIR transmission spectra. It showed several peaks and valleys. I have not been awarded a Nobel Prize yet.

@carrickrichards2457 4 ай бұрын

History that deserves to be remembered: Thank you

@KingsleyIkpa-agodo 4 ай бұрын

Thank you for yet another Monday motivation.

@pedritopa1 4 ай бұрын

Just found this channel, what a gem!

@cabanford 4 ай бұрын

Great channel. Instant view ❤

@HarryONeil 4 ай бұрын

Wow! What a great video! The history, the art work and photos, the "story telling". There's so much to life and history that I don't know. Never learned in the little "schooling" that I received. So it feels good, to learn something new today... Grateful that I'm still capable of learning anything! Considering all of the brain damage that one likely accumulated during the wild and crazy days of one's youth. Subscribed about 2 minutes into the video, having been "hooked" that fast.

@thesciencefurry 4 ай бұрын

4:07 X-Rays are not created by the heated up tungsten. It doesn't matter if it's cold or hot. X-Rays are created by the deceleration of the fast moving electrons.

@Rafaga777 4 ай бұрын

Thanks for another highly interesting video.

@RationalThinker118 4 ай бұрын

Thank you for watching! Glad you enjoyed it 😁

@supreetsahu1964 4 ай бұрын

❤❤

@RationalThinker118 4 ай бұрын

Wow, thank you so much... 🤯

@elmolewis9123 4 ай бұрын

Very well-done.

@tsparker99 4 ай бұрын

Your explanation of the anode heating to produce X-rays is incorrect. The anode heating is the result of the electrons striking the anode, but the X-rays will be generated immediately as result of their interaction with the electrons and nucleus of the tungsten atoms comprising the anode. The heating will occur after enough electrons have been collected.

@gavinedmondstone316 4 ай бұрын

In my working life X-ray powder diffraction was my preferred way of identify unknown materials that came my way.

@jhonwask 3 ай бұрын

I love this channel, but unfortunately, KZbin is making it more difficult to watch with the mandatory 10 minute commercials.

@copernicofelinis 4 ай бұрын

There's nothing to Bragg about.

@Tinker1950 4 ай бұрын

That will go straight over the head of most here.

@LuminosityUK 4 ай бұрын

Go to your room and contemplate your life choices 😂

@Blu3B33r 4 ай бұрын

This is so cool! I just looked up the wavelengths of x-rays and they are approximately the size of molecules and atoms, which makes sense from the diffraction. Since the wavelengths of Gamma rays are even shorter, at the size of an atomic nuclei, does it mean we can take refraction patterns of nuclei as well?