Elektronenergiförlustspektroskopie

Elektronenergiförlustspektroskopie, often abbreviated as EELS, is an analytical technique used to determine the elemental composition and electronic structure of a material. It is typically performed within a transmission electron microscope (TEM) or a scanning transmission electron microscope (STEM). In EELS, a beam of monoenergetic electrons passes through a thin sample. As the electrons interact with the sample, they can lose energy through various inelastic scattering processes.

The energy lost by these electrons is measured using an electron energy loss spectrometer, which is attached to the microscope. The resulting spectrum displays the intensity of transmitted electrons as a function of their energy loss. Characteristic energy loss peaks in the spectrum correspond to specific electronic transitions within the material, such as the excitation of plasmons or the ionization of core electrons.

By analyzing these energy loss features, information about the sample's elemental composition can be obtained, as ionization edges are unique to each element. Furthermore, the shape and position of these edges, as well as the presence of other features like plasmon peaks, provide insights into the chemical state, bonding, and electronic band structure of the material. EELS is a surface-sensitive technique and can be used to analyze very small sample volumes, making it invaluable for studying nanoscale materials, interfaces, and defects.