Atomically resolved AFM investigations of an amorphous barium silicate surface

In this work the investigation of an amorphous barium silicate surface with the atomic force microscope (AFM) under ultrahigh vacuum conditions is described. We show atomically resolved images of a disordered surface. Using the atomic positions it is possible to calculate radial distribution functions, which can be compared with data from neutron diffraction measurements. The analysis of the interatomic distances supports the view, that the glass consists of a network of SiO4 tetrahedra and terminates with oxygen atoms at the surface. In the range 0.3 nm-1 nm characteristic distances are found, which points to the existence of some medium-range order. The results provide an unique insight into the structure of glasses and may lead to a deeper understanding of the interactions present in such amorphous solids.