Structure and spectroscopy of surface defects from scanning force microscopy: Theoretical predictions

A possibility to study surface defects by combining noncontact scanning force microscopy (SFM) imaging with atomically resolved optical spectroscopy is demonstrated by modeling an impurity Cr(3+) ion at the MgO(001) surface with a SFM rip. Using a combination of the atomistic simulation and the ab initio electronic structure calculations, we predict a topographic noncontact SFM image of the defect and show that its optical transitions can be either enhanced or suppressed depending on the tip atomistic structure and its position relative to the defect. These effects should allow identification of certain impurity species through competition between radiative and nonradiative transitions.