The presence of internal boundaries can significantly influence many important properties of materials, such as fracture toughness, creep, electrical conductivity and magnetic behavior. Interfacial structure, chemical composition and bonding, on a nanometer length scale, are often controlling and sought after factors influencing these properties. An electron spectroscopic technique, known as energy-loss near edge structure (ELNES) analysis, can be utilized to probe compositional and bonding variations with a spatial resolution less than 1 nm and is therefore well suited to this endeavor.

When a fast electron passes through a material in an electron microscope, it collides with the electrons bound to the atoms in that sample. As a result, the fast electron often gives up a small fraction of its kinetic energy to the bound electrons. The laws of quantum mechanics dictate that these so-called inelastic scattering events will only take place if the bound electron can gain enough energy to enter an empty energy level.