Electron scattering in scanning probe microscopy experiments

It has been shown that electron transitions, as measured in a scanning tunnelling microscope, are related to chemical interactions in a tunnelling barrier. Here, we show that the shape and apparent height of subatomic features in both, measurements of the attractive forces in an atomic force microscope, and measurements of the tunneling current between the Si(1 1 1) surface and an oscillating cantilever, depend directly on the available electron states of the silicon surface and the silicon tip. Simulations and experiments confirm that forces and currents show similar subatomic variations for tip-sample distances approaching the bulk bonding length.