Name: 量子物理学で原子をトレースする顕微鏡 (The Microscope That Uses Quantum Physics to Trace Atoms)
Uploaded: 2021-01-14T10:46:28.000Z
Duration: 10 min 31 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

In the late 1970s, two physicists in Zurich, Switzerland,

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wanted to do something no one had done before:

see the individual atoms in a sheet of metal.

Their names were Gerd Binnig and Heinrich Rohrer,

and at the time, they were both interested in studying materials

that could be used in electronics, like silicon.

They thought that if scientists could just see these surfaces

at an atomic level, they'd be able to understand them better,

and then, maybe, they could make electronics that were more

The problem was, Binnig and Rohrer would have to invent

new technology before they had any hope of doing that.

But they were excited about the challenge and the chance

Because along the way, these two scientists invented a new type

of microscope that's made its way into labs all around the world,

where it's transformed our study of things ranging

Just a few decades ago, seeing a single atom was absurdly difficult.

A few microscopes had managed it under special circumstances,

like if the atoms were isolated on a thin needle.

But this wouldn't be enough for Binnig and Rohrer.

They wanted to see all the individual atoms on a whole surface.

Because, well, electronics components aren't just made of

single atoms; they're made of much larger materials.

Unfortunately, at this scale, regular optical microscopes —

like the kind you might have seen in science class —

They're able to see small objects because of how light passes

But the wavelength of light is much bigger than the length of an atom,

they can't make out anything near the size of a single atom.

So the first microscopes to look at these things worked differently.

For example, electron microscopes (which showed up in the 1930s)

fired beams of electrons through their samples and then

There, the pattern they made revealed the structure of the object

But these microscopes still didn't have high enough resolution

They relied a lot on computers to fill in the blanks.

So Binnig and Rohrer wanted to invent a new kind of microscope

They came up with a design that could potentially zoom in on things

10 times smaller than the best existing microscopes.

According to their plan, it would work kind of like a needle

The resolution would come from the sharpness of their needle —

because the more detail a needle can trace,

In this case, Binnig and Rohrer wanted to be able to detect

each and every atom on a surface, so their needle needed

In fact, its tip had to be on the order of one atom thick.

The two researchers used a technique called electrochemical etching

To make a needle this way, you start with a regular piece of wire.

Binnig and Rohrer went with one made of tungsten.

You connect that wire to another piece of metal —

Then, you dunk the whole thing in a hydroxide solution

and leave part of the tungsten wire poking out.

Since that tip is exposed, the liquid forms what's called

a meniscus around it, meaning the liquid gets slightly drawn upward.

Next, if you apply a voltage between the two metals, charge will

And that will set off a chemical reaction at the meniscus.

The submerged tungsten will react with hydroxide in the solution,

This tungstate dissolves away, leaving the wire to get thinner

Essentially, the metal gets chemically eroded away.

Eventually, the wire becomes so thin that it breaks!

And it leaves behind an extremely sharp tip — ideally one-atom thick.

But this process isn't perfect, so the tip normally still needs

Fortunately, even on their first attempt,

They were able to sharpen the tip by exposing it

And I mean very high — like, high enough to make the molecules

restructure themselves, which created a sharper point.

But making the tip was only half the battle.

Next, Binnig and Rohrer had to lower it into the surface

Except first, since they were dealing with such fine detail,

they needed to completely control any vibrations —

otherwise the tip or the sample could move in unpredictable ways.

Because all sorts of things create vibrations — people talking,

At the atomic level, even a footstep can seem like an earthquake.

So the two researchers decided to levitate the entire apparatus

Which is super practical and as a bonus, gives your experiment

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量子物理学で原子をトレースする顕微鏡 (The Microscope That Uses Quantum Physics to Trace Atoms)

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