LAUSR

Electron energy-loss spectroscopy (EELS) using a scanning transmission electron microscope (STEM) provides information on the local electronic structure around an atomic column irradiated by the incident electron probe. In this study, we present a method for detecting the directionality of chemical bonds with atomic resolution by selecting a specific atomic column and the direction of momentum transfer with an off-axis collection aperture in the STEM-EELS measurement. It is shown that the oxygen K-edge fine structures in SrTiO3 measured from the crystallographically equivalent oxygen sites, which are in TiO-planes perpendicular to the electron probe direction, show different structures depending on the directionality of the σ-bond between the oxygen and titanium atoms. This method opens up a way to explore the electronic states in anisotropic materials and interfaces with atomic resolution.Electron energy-loss spectroscopy (EELS) using a scanning transmission electron microscope (STEM) provides information on the local electronic structure around an atomic column irradiated by the incident electron probe. In this study, we present a method for detecting the directionality of chemical bonds with atomic resolution by selecting a specific atomic column and the direction of momentum transfer with an off-axis collection aperture in the STEM-EELS measurement. It is shown that the oxygen K-edge fine structures in SrTiO3 measured from the crystallographically equivalent oxygen sites, which are in TiO-planes perpendicular to the electron probe direction, show different structures depending on the directionality of the σ-bond between the oxygen and titanium atoms. This method opens up a way to explore the electronic states in anisotropic materials and interfaces with atomic resolution.