Lateral Manipulation of Single Electrons within Atom-Defined Nanostructures via nc-AFM*

In recent years non-contact atomic force microscopy (nc-AFM) has been used to study and control the charge of surface-supported species by exploiting its atomic resolution and single electron sensitivity. Still, few studies have demonstrated the ability to laterally manipulate charge between single atoms or molecules. We investigate atom-defined charge configurations composed of patterned silicon dangling bonds on a hydrogen-terminated Si(100)-2x1 surface. With the tip-sample separation as our key experimental parameter we uncover two interaction regimes: a strongly interacting regime where we can controllably position single electrons within the structures; and a weakly interacting regime, approximating field-free conditions, where we can track the position of charge within the structures over time. Via atomic manipulation we design symmetric and asymmetric confining potentials; subsequently we demonstrate the ability to strongly enhance the occurrence of ground and excited state charge configurations.