What is Scanning tunneling microscope (STM)?

A scanning tunneling microscope is like a super tiny magnifying glass that can see individual atoms on a surface.

Imagine you have a chocolate bar, and it's so dark you can't see the little squares inside. Now imagine you had a special flashlight that could show you each tiny square, even if they were super close together. That’s what an STM does, but for things much smaller than chocolate squares, like atoms.

The STM uses a very thin tip, like the point of a pencil, that moves just above the surface it's looking at. This tip is so close to the surface, almost touching it, that tiny electric currents can flow between them. These currents help the STM "feel" the shape of the surface and map out where each atom is.

Think of it like a blind person reading Braille, they use their fingers to feel the bumps on paper to know what letters are there. The STM uses electric currents to "feel" the atoms, telling us exactly how they're arranged. This helps scientists see and even move atoms around, like rearranging pieces of a puzzle!