Probing core-electron orbitals by scanning transmission electron microscopy and measuring the delocalization of core-level excitations

By recording low-noise energy-dispersive x-ray spectroscopy maps from crystalline specimens using aberration-corrected scanning transmission electron microscopy, it is possible to probe core-level electron orbitals in real space. Both the $1s$ and $2p$ orbitals of Sr and Ti atoms in $\mathrm{SrTi}{\mathrm{O}}_{3}$ are probed, and their projected excitation potentials are determined. This paper also demonstrates experimental measurement of the electronic excitation impact parameter and the delocalization of an excitation due to Coulombic beam-orbital interaction.