Electron Energy-Loss Spectroscopy (EELS)

This chapter outlines some basics of the Electron Energy-Loss Spectroscopy (EELS) technique and illustrate procedures for extracting quantitative information. Near-surface sensitivity is obtained at higher electron energies, provided the electrons arrive at a glancing angle to the surface, such that they penetrate only a short distance below the surface before being scattered out. Thus, it is possible to do reflection EELS at energies as high as 100keV. The chapter focuses on transmission EELS carried out with the aid of a conventional or scanning transmission electron microscope, where the incident energy is typically in the range 80-400keV. The imaging lenses are not essential for EELS but are useful in providing a small-diameter spot which forms the object point for the spectrometer. Electron spectrometers take many different forms but the only kind which has fractional resolution sufficient for EELS at high incident energy is the magnetic-prism design.