how does the scanning tunneling micro scope work?

Question

anonymous · Answer

Hi there. I hav done a bit of reasearch on the internet and  pretty much a STM (scanning tunneling microscope) is a device that uses a tip that ends in a single atom and a voltage that passes though the tip and the sample. The Electrons use a quantum mechanical effect to ‘tunnel’ from the tip to the sample or vice versa. The current that results depends upon the distance between the probe tip and sample surface. The tip is attached to a piezoelectric tube and voltage applied to the piezo rod is altered to maintain a constant distance for the tip from the surface. Changes in this voltage allows a three dimensional picture of the material surface to be built up as the tip is scanned back and forth across the sample.