How do electron microscopes detect electrons.

[grayson]

I have recently come across a dilemma. I can't figure out how electron microscopes detect the shape of electrons. Now, obviously you could just send them through a wire or something, but that would make them lose their shape. I am trying to make an electron microscope for a project (As the ones you can get are too cheap). I have figured out everything except detecting the shape of the electrons. Can somebody help me?

[swansont]

They don’t measure the shape of electrons. 

[John Cuthber]

13 hours ago, grayson said:

I have figured out everything except detecting the shape of the electrons.

If you think the shape of the electrons matters, then I very much doubt you have figured everything else out.

[grayson]

5 hours ago, John Cuthber said:

If you think the shape of the electrons matters, then I very much doubt you have figured everything else out.

I am going to ignore you not using common sense and explain what I meant. I mean the shape of multiple electrons. Like, how they form to show the shape of the subject.

[swansont]

4 hours ago, grayson said:

I am going to ignore you not using common sense and explain what I meant. I mean the shape of multiple electrons. Like, how they form to show the shape of the subject.

For a SEM, you bounce a focused beam of electrons off of the target. They hit a screen that shows the image, like a CRT TV.

[John Cuthber]

4 hours ago, grayson said:

I am going to ignore you not using common sense and explain what I meant. I mean the shape of multiple electrons. Like, how they form to show the shape of the subject.

I'm sorry you expressed yourself so badly.
The answer to your question is "it depends". There's several types of electron microscope and they use a variety of methods to form an image.
If you haven't figured out how to see that then I'm right. You  haven't figured everything else out.
 

[Sensei]

5 hours ago, grayson said:

I am going to ignore you not using common sense and explain what I meant. I mean the shape of multiple electrons. Like, how they form to show the shape of the subject.

Some people have been on the forum (any forum) too long and too bored with the forum and answering (newbie) people, they become unbearable and a cumbersome to the rest.. unable to answer any simple question.. We have seen this in the past.. Some of them were banned because they were too disruptive..

I'd call it professional forumer burnout..

Quote

How do electron microscopes detect electrons.

It's very simple. When you accelerate an electron with a well-known voltage, it hits something. Their kinetic energy ranges from zero to that voltage, expressed in eV (e.g., 5,000 V will get you from 0 to 5,000 eV K.E.) If it has high enough energy, it causes the electron to be ejected. When an electron is attracted to an atom or molecule, it must emit a photon. We have 1) electrons that have been ejected and 2) photons that were emitted by electrons attracted to an atom or molecule.

Ejected electrons and/or photons can be captured by sensors. Reflected electrons can be captured by sensors. Their energy (kinetic energy) (thus velocity), angle and time of flight from the primary emitter to the object and then to the sensor can be measured. A computer algorithm reproduces this in the computer's memory and displays it on the screen.

 

 

On 11/18/2023 at 12:04 AM, grayson said:

I have recently come across a dilemma. I can't figure out how electron microscopes detect the shape of electrons. Now, obviously you could just send them through a wire or something, but that would make them lose their shape. I am trying to make an electron microscope for a project (As the ones you can get are too cheap). I have figured out everything except detecting the shape of the electrons. Can somebody help me?

Don't be silly. Electron microscopes are damn expensive and this is not a project you can do at home. At least not you..

 

 

Making an electron gun requires a fairly good vacuum.

https://en.wikipedia.org/wiki/Electron_gun

 

 

The number of calculations here is in the billions, so your little knowledge of Python is not enough to create a program. You need C/C++.

Edited November 18, 2023 by Sensei

[John Cuthber]

12 hours ago, Sensei said:

Some people have been on the forum (any forum) too long and too bored with the forum and answering (newbie) people, they become unbearable and a cumbersome to the rest.. unable to answer any simple question.. We have seen this in the past.. Some of them were banned because they were too disruptive..

I'd call it professional forumer burnout..

Is that a reference to this?
 

 

On 11/18/2023 at 12:10 AM, swansont said:

They don’t measure the shape of electrons. 

 

12 hours ago, Sensei said:

Making an electron gun requires a fairly good vacuum.

https://en.wikipedia.org/wiki/Electron_gun

Thankfully, not all electron microscopes use an electron gun.
The requirement for a vacuum is  last century's technology.
https://www.sciencedirect.com/science/article/abs/pii/0006291X91910328

 

 

12 hours ago, Sensei said:

Don't be silly. Electron microscopes are damn expensive and this is not a project you can do at home. At least not you..

Calling the newbies "silly" is a nice example of this.

 

12 hours ago, Sensei said:

Some people have been on the forum (any forum) too long and too bored with the forum and answering (newbie) people, they become unbearable and a cumbersome to the rest.. unable to answer any simple question.

But to be fair this
 

 

12 hours ago, Sensei said:

this is not a project you can do at home. At least not you..

is correct; just like I said.
 

 

13 hours ago, John Cuthber said:

You  haven't figured everything else out.

 

[Sensei]

29 minutes ago, John Cuthber said:

Thankfully, not all electron microscopes use an electron gun.
The requirement for a vacuum is  last century's technology.
https://www.sciencedirect.com/science/article/abs/pii/0006291X91910328

https://en.wikipedia.org/wiki/Scanning_tunneling_microscope

"Not to be confused with scanning electron microscope (SEM)."

https://en.wikipedia.org/wiki/Scanning_electron_microscope

"Not to be confused with Scanning tunneling microscope."

STM != SEM..

 

[John Cuthber]

24 minutes ago, Sensei said:

https://en.wikipedia.org/wiki/Scanning_tunneling_microscope

"Not to be confused with scanning electron microscope (SEM)."

https://en.wikipedia.org/wiki/Scanning_electron_microscope

"Not to be confused with Scanning tunneling microscope."

STM != SEM..

 

I wasn't aware that anyone had said that STM and SEM were the same.
Can you point out where they did so?

I obviously know they are different, you may recall that I pointed out that you can run one of them under water and that it doesn't have an electron gun.


The OP just said "electron microscopes".
That term includes TEM, STEM PEEM and SEM.

If I was an amateur trying to build an electron microscope, It'd build a tunneling one. (No high voltages, no vacuum chamber and also past experience of helping rebuild one about 1990)

Edited November 19, 2023 by John Cuthber

[studiot]

When they were first introduced electron microscopes became the bees knees of instrumental analysis.

But they were large, cumbersome and expensive.

And the supporting instrumentation was even more so. (no modern computers in 1931)

Today they are used in conjunction with both computers and other instruments such as Field ion microscopes, X ray flourescence spectrometers, Ion traps, and laser technology to gain significant quantitative information as well as the qualitative shapes from the past.

They are of course also more compact and there are cheaper versions and many variations on their method of applications.

 

On 11/17/2023 at 11:04 PM, grayson said:

I have recently come across a dilemma. I can't figure out how electron microscopes detect the shape of electrons. Now, obviously you could just send them through a wire or something, but that would make them lose their shape. I am trying to make an electron microscope for a project (As the ones you can get are too cheap). I have figured out everything except detecting the shape of the electrons. Can somebody help me?

Was your question prompted by the Nobel 2023 prize for electron imaging ?

https://www.weforum.org/agenda/2023/10/mrna-vaccines-electrons-nobel-prizes-in-2023/

[Sensei]

2 hours ago, John Cuthber said:

The OP just said "electron microscopes".
That term includes TEM, STEM PEEM and SEM.

STM (from the article that you just linked) is not one of them..

 

  

3 hours ago, John Cuthber said:

Thankfully, not all electron microscopes use an electron gun.
The requirement for a vacuum is  last century's technology.
https://www.sciencedirect.com/science/article/abs/pii/0006291X91910328

 

 

2 hours ago, John Cuthber said:

If I was an amateur trying to build an electron microscope, It'd build a tunneling one. (No high voltages, no vacuum chamber and also past experience of helping rebuild one about 1990)

..then you would not build an electron microscope, but a tunneling microscope.. It's a completely different technology, with different operating principles..

..what is your definition of an electron microscope.. ?

"An electron microscope is a microscope that uses a beam of electrons as a source of illumination. They use electron optics that are analogous to the glass lenses of an optical light microscope to control the electron beam, for instance focusing them to produce magnified images or electron diffraction patterns. As the wavelength of an electron can be up to 100,000 times smaller than that of visible light, electron microscopes have a much higher resolution of about 0.1 nm, which compares to about 200 nm for light microscopes."

STM is not listed on the list of electron microscopes, and they clearly stated: don't confuse with STM:

https://en.wikipedia.org/wiki/Electron_microscope

 

ps. Personally, I would prefer to build an SEM.

ps2. A good starting point would be to create a 3D printer or 2D printer/plotter with high motion resolution (so that the electron gun remains stable and the sample moves slightly below).

 

Edited November 19, 2023 by Sensei

[studiot]

Please gentlemen stop pointless arguing over semantics.

 

Is this what Fred Flintstone has in mind when he invented the neolithic hammer ?

They are both hammers.

Edited November 19, 2023 by studiot

[iNow]

1 hour ago, studiot said:

stop pointless arguing over semantics. <…> They are both hammers.

So is this 😉

[John Cuthber]

6 hours ago, Sensei said:

STM (from the article that you just linked) is not one of them..

 

Thanks for letting me know that the microscopes I worked on in which electrons tunnelled giving a map of the surface electron fermi potential were not electron microscopes.
 

 

6 hours ago, Sensei said:

then you would not build an electron microscope, but a tunneling microscope

I'm not going to build a tunnelling proton microscope.
It's possible, but  much easier to use electrons.
Which is why scanning tunnelling electron microscopes are, in fact, electron microscopes.
(Wiki is not God)

These are electron microscopes too.
https://en.wikipedia.org/wiki/Field-emission_microscopy
They don't have electron guns (in the definition Sensei posted)
But they are tunnelling microscopes. The field emission relies on tunnelling.

 

6 hours ago, Sensei said:

A good starting point would be to create a 3D printer or 2D printer/plotter with high motion resolution (so that the electron gun remains stable and the sample moves slightly below).

Somehow, I think the folk who designed scanning electron microscopes  where pretty much the only  "moving part" was an electron beam, knew what they were doing.

 

4 hours ago, iNow said:

So is this 😉

[iNow]

lol. Well played