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ATOMIC SHORTS
Ripples on the surface
When you’re watching this movie,
you might notice that there are little ripples on the surface.
And those ripples are actually real.
What you see there are electrons
that are stuck in the surface layer of this copper.
The electrons in a metal – copper is a metal – electrons in a metal
are always confined to the inside of the metal.
This particular surface that we’re using, some electrons are actually stuck in the surface.
They can’t come out but they also can’t go back into the bulk of the material.
And that surface layer, we call that a 2-dimensional electron gas,
so the electron’s confined in 2 dimensions.
Those then behave like waves,
like the waves that you see when you throw a pebble in a lake.
So you see these, these, these ripples on the surface
and those are really ripples in the electron density,
the number of electrons changes around the atoms.