Dual tunnelling sites on metal-oxide surfaces: a scanning tunnelling microscopy study of (110)

Abstract

Two types of atomically resolved scanning tunnelling microscopy (STM) images from a - surface are observed. Depending on the chemical identity of the tip apex, the five-fold coordinated surface cations can appear either as protrusions or as depressions. The interaction between the tip apex atom and the surface is examined and discussed in relation to image formation.