Question

what is the relationship of stm microscopy to quantum?More than 2-3 paragraphs should be explanatory.

Answer 1

The scanning tunnelling microscope (STM) uses the concept of quantum tunnelling to directly image atoms of a sample. The STM can be used to study the three-dimensional structure of a sample, by scanning the surface with a sharp metal conducting tip at an extremely small distance. Such an environment is conducive to quantum tunnelling: a quantum mechanical effect that occurs when electrons move through a barrier due to their wave-like properties. Tunnelling depends on the thickness of the barrier. If the barrier is reasonably thin, the probability function predicts some electrons will pass to the other side. This will create a current across the tunnel. The number of electrons that will tunnel is dependent on the thickness of the barrier, therefore the current through the barrier will also depend on the thickness. In this case, the distance between the sharp metal tip and the surface of the sample will affect the current measured by the tip. The tip is formed by one single atom, and it slowly scans across the surface at a distance of an atom's diameter. By paying attention to the current, the distance can be kept more or less constant, allowing the tip to move up and down according to the structure of the sample. The STM is able to follow even the smallest details.