Improvement of EXAFS Theory

Abstract

The single-electron single-scattering theory of EXAFS described in the previous chapter forms the basis of data analysis in EXAFS spectroscopy. In many cases, all it requires is parameterization of the relevant variables or functions. These variables or functions can then be determined from model compounds or from theoretical calculations. For some specialized applications or in some particular systems, however, this phenomenological theory is inadequate and modification or generalization of the theory is required. In this chapter, possible breakdowns of the single scattering theory of EXAFS will be discussed:

• 1. Phase transferability problem caused by uncertainty in energy threshold;

• 2. Amplitude transferability problem caused by inelastic scattering processes at (a) the central atom and (b) the neighboring environment;

• 3. Smearing effects caused by static and thermal disorders;

• 4. Multiple scattering effects caused by intervening atoms.