Electrons have wave-particle duality. This is well pronounced at an ultra-small scale. In this talk, we will explore this behaviour using scanning probe microscopy (SPM). This unique microscope allows us to image small structures down to atomic scale, and can be used for characterizing their physical properties.
Electrons can get confined in a vacuum gap between two conductive surfaces of a scanning tunneling microscope (STM). These electrons can interfere and form standing waves in the vacuum gap of the STM, which is analogous to a particle in a box in quantum mechanics. The corresponding energy levels for these standing waves can be measured via increase of tunneling current. An STM can be used as a novel tool for a surface potential evaluation because the positions of the energy levels are greatly sensitive to the surface potential.
When electrons tunnel through a potential barrier, they can only tunnel by units of e. By embedding a metallic nanoparticle between two tunnel barriers, a nanoparticle can be charged with single electrons. Single electron charges give rise to discrete force changes, which can be measured by a hybrid scanning tunneling atomic force microscope (STM-AFM).
SPM can also be used for constructing/modifying small artificial structures. These structures not only provide a test bed for quantum mechanics, but may also provide a way to overcome optical lithographical limits.