Absorption Edge Spectroscopy

In general absorption edges are characteristic of the absorber. The wavelength at which they occur are fixed so that edge spectroscopy can be used as an analytical tool to identify elemental compositons.

In the vicinity of an absorption edge there is a "fine structure." When the photoelectric effect cause the emission of a photon from the excited atom, the outgoing wavelet is backscattered by neighboring atoms. This causes a modulation in the apparent absorption coefficient. This modulation can be analyzed to determine the nearest neighbor environment (structure) around the excited atom type.