Imaging isodensity contours of molecular states with STM

Abstract

We present an improved way for imaging the density of states of a sample with a scanning tunneling microscope, which consists in mapping the surface topography while keeping the differential conductance (dI/dV) constant. When archetypical C60 molecules on Cu(111) are imaged with this method, these so-called iso-dI/dV maps are in excellent agreement with theoretical simulations of the isodensity contours of the molecular orbitals. A direct visualization and unambiguous identification of superatomic C60 orbitals and their hybridization is then possible.