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What are “actual pictures” of atoms actually pictures of?

askamathematician.com

1–10 of 57 posts

Re: What are “actual pictures” of atoms actually pictures of?

#2
Well, as the article points out, the things being imaged are most definitely actual atoms. The only thing TFA is nitpicking about is that light isn't used to image those atoms.

This is about as interesting as pointing out the fact that an ultrasound picture of a baby isn't an "actual picture", since we use sound instead of light to make the image.

Re: What are “actual pictures” of atoms actually pictures of?

#4
Well, an image is a representation of something in a way that humans can see. Whether waves, electrons or poking sticks were used doesn't change the fact of it being an image.

Say, a dolphin's echolocation might let him "see" a diver using sound - http://i.imgur.com/CS6wkNV.png , which would still be considered an image, even though it's using sound.

Anyway that's just semantics, and an STM is still a damn impressive piece of kit.

Re: What are “actual pictures” of atoms actually pictures of?

#5

Well, as the article points out, the things being imaged are most definitely actual atoms. The only thing TFA is nitpicking about is that light isn't used to image those atoms. This is about as interesting as pointing out the fact that an ultrasound picture of a baby isn't an "actual picture", since we use sound instead of light to make the image.

The concept of the scanning tunneling microscope is so simple and ridiculous that it was probably thought of and dismissed long before someone built one. "You're going to image atoms by dragging a tiny needle across them"? Yet that's pretty much how it works.

The first one was built in 1981, but one could have been built in the 1950s. Piezoelectric crystals were known. Raster scanning circuits were known. Feedback circuits for controlling the height were known. The tricks for making one-atom sharp points were not known, but the earliest STMs just stretched out a tiny platinum wire until it broke, and sometimes you got a one-atom point.

Hobbyists have built STMs.[1] It's simpler than building a 3D printer.

[1] https://dberard.com/home-built-stm/

Re: What are “actual pictures” of atoms actually pictures of?

#7
One of my first jobs out of college was doing manual chip layouts (which will give you some idea of how old I am). Once the layout was done, the design was sent to a "mask house" which would print the layout onto a series of glass plates (the "masks") which were then used in the chip fabrication process. When the masks for my first chip came back I popped one of them into a bench microscope to see what it looked like. I was expecting to see my design in black-and-white printing, but all I could see (of course) were rainbows because the mask was effectively a diffraction grating. This was my first visceral encounter with quantum mechanics. I knew there was a pattern there, but I could never see it directly with my own eyes.

Re: What are “actual pictures” of atoms actually pictures of?

#9
post #5

Well, as the article points out, the things being imaged are most definitely actual atoms. The only thing TFA is nitpicking about is that light isn't used to image those atoms. This is about as interesting as pointing out the fact that an ultrasound picture of a baby isn't an "actual picture", since we use sound instead of light to make the image.

The concept of the scanning tunneling microscope is so simple and ridiculous that it was probably thought of and dismissed long before someone built one. "You're going to image atoms by dragging a tiny needle across them"? Yet that's pretty much how it works. The first one was built in 1981, but one could have been built in the 1950s. Piezoelectric crystals were known. Raster scanning circuits were known. Feedback ci…

I know, I did a benchtop STM lab for my Nuclear Physics course some years ago. Most of the day was spent trying to make single atom needles by a wrist-flick technique for cutting platinum wire with some sharp pliers.

Re: What are “actual pictures” of atoms actually pictures of?

#10
post #3

The linked video "A Boy And His Atom: The World's Smallest Movie" is entertaining. IBM made a stop-motion animated movie from individual atoms. https://www.youtube.com/watch?v=oSCX78-8-q0&feature=youtu.be

It was linked with the text "all manner of jackassery" I am glad to know I am not the only one who thought that video was a waste of time.
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