Optical Spectroscopy of Surface Nanostructures with Atomic Spatial Resolution

By spectroscopic analysis of visible light that is emitted from the tip-sample gap of the scanning tunneling microscope (STM), one can obtain information on the electronic transitions in individual and specific surface nanostructures with atomic spatial resolution. We have used this technique to investigate the electronic transitions in individual quantum wells of Al_xGa_1-xAs/GaAs structures and at different locations within a single well. Also an atomically localized electronic transition on the reconstructed Au(110)-(2×1) surface was found by this method.