
What are “actual pictures” of atoms actually pictures of? - ColinWright
http://www.askamathematician.com/2016/06/q-what-are-actual-pictures-of-atoms-actually-pictures-of/
======
semi-extrinsic
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.

~~~
Animats
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/](https://dberard.com/home-built-stm/)

~~~
semi-extrinsic
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.

~~~
joncrocks
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.

~~~
Pyxl101
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?

~~~
quanics
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.

~~~
tostitos1979
Man .. I know what my next hobby project is going to be :)

Dumb question .. I get that the needle scans a surface and you get the quantum
tunneling effect between the atom you are "looking at" and the tip of the
needle. What I don't get is how one figures out depth. For each X,Y position,
do you just keep going down until you touch something, and then move up, and
go to the next position? If so, apart from the issue with 1 atom tip, I
imagine the next problem would how to increment X and Y by 1 atom.

P.S. I think some of the marketing put out on these things really confuses the
issue. Sure .. it gets people excited about science but it gives people the
wrong intuition. As a non-physics person, I got a lot out of this article.

~~~
maybecorrect
In the simplest configuration have a X-Y stage that you raster, along with Z
axis control - generally these are all piezo controlled. Your signal is then
acquired by maintaining a constant tunneling current while you raster, so you
track the Z axis position as you raster.

This means that you're getting a "pseudo-height" map - if you had a surface
with 2 types of atoms, both the same size, but with different tunneling
barriers, you would see them appear to be different sizes.

------
lisper
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.

~~~
kens
What era of chip layout was this? I'm surprised that manual chip layout was
still being done when chip features were that small. I look at 1970s chips a
lot, and the features are easily visible under a microscope, as they are much
larger than wavelength-sized.

~~~
lisper
This was in 1984, and it was for experimental chips, not production chips. The
layout was done using CAD tools, but the placement was all manual.

Also, I think they were analog chips, not digital. I'm not sure. This was a
co-op job in my first year at college at the IBM plant on Cottle Road, and I
was never fully in touch with the big picture. I think they were making big-
ass hard drives, and the chips I was working on were part of the circuitry
that amplified the raw signal from the read-write head, but those details were
way above my pay grade.

~~~
NegativeLatency
How many features were on the chip?

~~~
lisper
I have no idea. This was more than 30 years ago. But the number of transistors
was in the hundreds or maybe low thousands. (I can't recall if I was laying
out individual transistors or functional modules.)

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kens
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](https://www.youtube.com/watch?v=oSCX78-8-q0&feature=youtu.be)

~~~
asmithmd1
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.

~~~
alva
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!)

------
Artlav
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](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.

~~~
blowski
Yeah, it's not a photo but it is an image or picture. The article is doing a
bad job of defining its terms, but still it's interesting for a layman like
myself.

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joshumax
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.

------
fluxsauce
> This technology has been around for decades and, like the advent of the
> synth, has given rise to all manner of jackassery.

What's with the synthesizer hate? That seems random.

~~~
Stratoscope
That was the weirdest part of this article. I enjoyed the whole thing until
the end, but why does the author call IBM's cute and amazing movie "A Boy and
His Atom" _jackassery_?

~~~
foota
I think it's being used to mean a sort of playing around.

------
Aelinsaar
I love that offhanded comment about how the helical structure of DNA is not at
all obvious from that crystallography. All the more impressive then, the
history of that discovery.

~~~
dekhn
Like many things about the article it's hard to tell when the author is
joking.

Knowing DNA was helical from the fiber diffraction images (not
crystallography- they were working with DNA fibers, not crystals) was actually
"obvious". A helix forms a distinctive cross pattern, this can be (and was)
predicted easily from diffraction theory applied to a helical structure.

------
jdetle
I strongly encourage anyone who is thinking about this to read: "A Different
Universe" by Robert Laughlin. This is one of his main concerns of modern
science, and although its kind of a muddled argument he thinks that the
emergent phenomena captured by photographs are entirely misapplied to atomic
forces.

------
anotheryou
super impressive DIY microscope to see atoms:

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

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mehrdada
I cannot see (pun intended) how "normal" seeing is fundamentally different.
One basically sees by measuring their interactions with photons and deducing
how something "looks like" vs. measuring interactions with electrons in STM
and making a similar deduction.

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warrenmar
You can also hear it when you move atoms.

[https://www.youtube.com/watch?v=FbLvy-
ayi4A](https://www.youtube.com/watch?v=FbLvy-ayi4A)

------
polytap
The strange barb at music synthesizers was uncalled for.

~~~
yborg
His point was that it is common for a "new" technology to be used just ...
because it's there. There was a lot of very bad music made in the early-80s
when digital synths became available, and IBM using an AFM to make an
advertising blurb could be considered in thie vein.

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weberc2
I think we may have DDOSed this site. I'm getting "Error establishing a
database connection".

------
greypowerOz
for fun:
[https://www.youtube.com/watch?v=t60EfnqZKrQ](https://www.youtube.com/watch?v=t60EfnqZKrQ)

How To Make Something One Atom Thick Tom Scott

------
moptar
There's a philosophy idea that in order to say we can "see" something, we have
to be able to collect consistent information by several different methods. For
example if all we have is a STM, then we don't know which parts of the image
are artifacts and which are real so we haven't seen anything. But if we have
an STM and crystallography, we can have more faith in the features that are
common to both images - such as interatomic distances and the geometry of
crystal structure. But we still couldn't say that we've seen the shape of an
atom since that would look different in each instrument's image.

A great example is people who "discovered" lost cities under the sea. They saw
regular patterns of lines on the seafloor in Google Earth and interpreted them
as ancient roads or walls. But they were only seeing artifacts from ships that
had sailed back and forth in straight lines collecting data. If they had
looked both at those sonar scans and some other data for the same location,
they would have only seen the lines on one image and been able to conclude
that they were either an artifact of the sonar or below the level of
sensitivity of the other instrument.

