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TOM: I am with Kate Oliver and Andy Collins
from the Centre for Functional Nanomaterials at the University of Bristol.
And they're going to show me how we see tiny tiny tiny things.
KATE: So we're nanotechnologists, and for us, a tiny thing is an atom.
TOM: Right. Okay.
KATE: So we have one way of seeing atoms.
It's called a scanning tunnelling microscope.
And it uses the fact that if you bring a tip close to a surface,
there's a probability that because of quantum --
TOM: I love that explanation.
KATE: -- the electrons will go from the surface to the tip.
So basically, as you move the tip along,
if you hit a bump, more electrons will tunnel up into the tip.
And that will give you an idea of how close the surface is.
TOM: But that means you need a tip that is one atom thick.
KATE: It means you need a tip that is very small.
TOM: Okay. Which is where you come in.
ANDY: So I'm going to show you how to make a tip that's one atom thick.
You need to get it as sharp as you possibly can for good imaging.
We've got a secret weapon of nanoscience:
Pliers. And wire cutters.
TOM: I kind of assumed there'd be some kind of
hideously expensive equipment required in this, but...
ANDY: So I've got some platinum wire.
TOM: Okay, that is hideously expensive.
ANDY: It's a platinum iridium alloy.
And we use platinum so that it doesn't conduct oxygen,
which would make the tip fatter.
Because we want one single, conductive atom at the surface of the tip.
So if I hold that wire in my pliers,
and I apply the wire cutters at a 45 degree angle...
..there we go!
That means you've got something that, in theory, is atomically sharp.
TOM: That's fantastic. So what do you do if it's not conductive?
Because quantum tunnelling only works with something that's conductive.
KATE: This is an atomic force microscope.
TOM: It's really cool! And it's actually scanning at the minute?
KATE: It is. You can see on the screen here, that is -- 20 micrometres across.
So that is about a fifth of the width of one of your hairs, Tom.
But we wouldn't be able to see anything on here
if it wasn't against a really flat, high-contrast background.
Luckily, we have a number of minerals that come in convenient flat sheets.
One of these is mica, which I have here.
But we can't be sure that we've only got one layer on the surface.
So for that, we have another high-tech nanoscience tool.
TOM: Which is sellotape.
KATE: Yes.
Adhere this down.
And it's stuck to just one of these layers of mica, or maybe a couple.
TOM: But the top layers?
KATE: Yes.
And then: peel it off, and can you see the faint outline?
TOM: There is. There is a faint outline of a square on there.
Which is -- is that just a one atom thick layer of mica?
KATE: Yep. And that implies that what's left is also entirely flat.
Giving us a really good contrast for any atoms, molecules, species --
these are some fibres we've got on top of this surface --
that we want to have a look at and see what they can do for us that's really useful.
TOM: So we have million-pound equipment around this lab.
And then we've got pliers and sticky tape.
ANDY: Yes.
TOM: That is wonderful. Kate Oliver, Andy Collins,
from the Centre for Functional Nanomaterials at the University of Bristol.
Thank you very much, guys!
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