Electron Energy Loss Spectrometry in the Electron Microscope

Intense efforts to understand the structure and properties of solids have taken place in several academic disciplines in parallel: physicists tending to concentrate on electronic structure defined in terms of the states available to electrons in an infinite, perfect solid; chemists tending to emphasize the bonding of atoms or ions by the overlap of electronic wavefunctions and by Coulombic forces between ions, regarding the solid as a particularly large molecule to which chemical methods can be applied; and the science of materials concerned more with the atomic structure of solids, both perfect and imperfect, a study which is the natural outcome of crystallography and the development of microscopies on the verge of atomic resolution. One satisfying aspect of electron energy loss spectrometry in the electron microscope is that it unites all three points of view in one instrument. It is by its nature interdisciplinary, at the triple point of physics, chemistry, and the science of materials. The techniques permit microanalysis, or more strictly correct, nanoanalysis, the determination of chemical composition point by point in the sample, as well as producing information on the electronic structure of the solid and its atomic structure via convergent beam diffraction (micro- or nano- diffraction) and imaging. In this chapter we concentrate on the relationship between EELS and other spectroscopies of solids (see also the Chapter by L.M.Trudeau).