I built an STM a while back for fun and when people ask me how I managed to "image" atoms I usually use the analogy of the STM being like a "microscope sonar" where the atoms are "blips" on a plane (the sonar map). Sure it's not actual EM radiation landing on a CMOS detector but it's still pretty neat nonetheless.
What are “actual pictures” of atoms actually pictures of?
21–30 of 57 posts
Re: What are “actual pictures” of atoms actually pictures of?
#22Earlier quoted context omitted.
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.
I worked in the lab at the Nation Physical Lab in the UK that had the low pressure + low temperature STM, we used to make the tips by dipping the ends in a very strong solution of NaOH. You relied on the surface tension as it dissolved to produce you a very sharp tip. Surprisingly easy.
Cool. I know people also buy tips, but they're expensive.
For really cool stuff, check out the CO functionalized tip AFM coming out of IBM in Zürich: https://www.zurich.ibm.com/st/atomic_manipulation/pentacene....
The AFM I used was mainly for teaching the concepts, so they wanted simple, cheap, low risk => strong NaOH was out.
The technique back then was, somehow, cutting at about 45° angle and twisting the pliers to make this angle go to zero while cutting/pulling. Then you had to put the tip in the machine and do test images to see whether the tip was good. Usually it wasn't, so you tried again. Finally you got a perfect tip, and maybe got two or three good images before you messed up the tip (from being a noob).
Re: What are “actual pictures” of atoms actually pictures of?
#23[deleted]
Re: What are “actual pictures” of atoms actually pictures of?
#24Well, 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.
Isn't it possible to make an image using light, but by computing the "real" image from the interference pattern (of a single non-repeating atom/structure)? And if there is more than one solution, then perhaps by using images from multiple angles, or with different wavelengths?
Re: What are “actual pictures” of atoms actually pictures of?
#25Earlier quoted context omitted.
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.
I worked in the lab at the Nation Physical Lab in the UK that had the low pressure + low temperature STM, we used to make the tips by dipping the ends in a very strong solution of NaOH. You relied on the surface tension as it dissolved to produce you a very sharp tip. Surprisingly easy.
How do you know if your tip is one atom wide or not?
Also, what would the shape of the tip look like if you drew it? I'm wondering what kind of general angles the surface has. Is it like a cone with a single atom at the tip? What kind of slope?
Re: What are “actual pictures” of atoms actually pictures of?
#26The strange barb at music synthesizers was uncalled for.
Re: What are “actual pictures” of atoms actually pictures of?
#27Well, 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…
Or even when the representation is something humans can't see. Hence the word "imagination".
Re: What are “actual pictures” of atoms actually pictures of?
#28Earlier quoted context omitted.
I worked in the lab at the Nation Physical Lab in the UK that had the low pressure + low temperature STM, we used to make the tips by dipping the ends in a very strong solution of NaOH. You relied on the surface tension as it dissolved to produce you a very sharp tip. Surprisingly easy.
How do you know if your tip is one atom wide or not? Also, what would the shape of the tip look like if you drew it? I'm wondering what kind of general angles the surface has. Is it like a cone with a single atom at the tip? What kind of slope?
The only real way to know if you had a single atom tip was to image a known surface. If the image was junk you probably had some funky tip states going on. HOPG (graphite) was the standard we typically used.
A good tip could be just about anything, from a nice cone to really jagged. One problem was any of the methods one has to view the tip can't actually resolve the single atom that is doing the imaging.
Re: What are “actual pictures” of atoms actually pictures of?
#29The 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.
Connecting incredibly difficult to understand scientific achievements with the simple notion of the common human desire for play and creativity is truly glorious.
A beautiful symbol of prowess, intelligence, creativity and humanity. I don't think anyone should underestimate the impact that a video like that can have on a child (or even a curious adult!)
Re: What are “actual pictures” of atoms actually pictures of?
#30The 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 is a nice video.
Also be sure to check out IBM's STM gallery for some more amazing images.
http://researcher.watson.ibm.com/researcher/view_group.php?i...