Electron energy loss spectroscopy

Some of the electrons will undergo inelastic scattering, which means that they lose energy and have their paths slightly and randomly deflected.

[1] The technique was developed by James Hillier and RF Baker in the mid-1940s[2] but was not widely used over the next 50 years, only becoming more widespread in research in the 1990s due to advances in microscope instrumentation and vacuum technology.

[4][5] EELS is spoken of as being complementary to energy-dispersive x-ray spectroscopy (variously called EDX, EDS, XEDS, etc.

EDX excels at identifying the atomic composition of a material, is quite easy to use, and is particularly sensitive to heavier elements.

There are several basic flavors of EELS, primarily classified by the geometry and by the kinetic energy of the incident electrons (typically measured in kiloelectron-volts, or keV).

Probably the most common today is transmission EELS, in which the kinetic energies are typically 100 to 300 keV and the incident electrons pass entirely through the material sample.

Instrumental developments have opened up the ultra-low energy loss part of the EELS spectrum, enabling vibrational spectroscopy in the TEM.

Scanning confocal electron energy loss microscopy (SCEELM) is a new analytical microscopy tool that enables a double corrected transmission electron microscope to achieve sub-10 nm depth resolution in depth sectioning imaging of nanomaterials.

SCEELM takes advantages of the newly developed chromatic aberration corrector which allows electrons of more than 100 eV of energy spread to be focused to roughly the same focal plane.