3D elemental mapping with nanometer scale depth resolution via electron optical sectioning...

Electron energy loss spectroscopy in the scanning transmission electron microscope has long been used to
perform elemental mapping but has not previously exhibited depth sensitivity. The key to depth resolution with
optical sectioning is the transfer of sufficiently high lateral spatial frequencies. By performing spectrum imaging
with atomic resolution we achieve nanometer scale depth resolution, enabling us to optically section an oxide heterostructure spectroscopically. Such 3D elemental mapping is sensitive to atomic scale changes in structure and composition and is more interpretable than Z-contrast imaging alone.