Internal photoelectric process

Since there will be a vacancy or hole where the captured electron was previously located, an electron from another energy level will fill the hole resulting in the emission of an X-ray and the creation of another hole. This second hole will be filled by another electron resulting in an X-ray of different energy, and so on. Thus, several characteristic X-rays can be emitted. It should be said that instead of X-ray emission, an internal photoelectric process can result in the emission of... 

EXAFS data are processed to obtain radial structure functions (RSFs). First, the non-EXAFS components are subtracted from the data. Pre-edge absorption is removed using the Victoreen correction (International Tables for Crystallography, 1969) of the form AX + BX . The monotonic decrease of absorbance beyond the edge, called the photoelectric decay, is subtracted out after approximating it either by a second degree polynomial or a spline-function (Eccles, 1978). The normalized x(k) is then expressed as... 

X-ray fluorescence of an element is a two-step process. For an isolated atom, the first step is excitation during which the interaction of the photon, given sufficient energy, leads to the stripping off of a lower shell electron such as a K electron. This photoelectric effect leads to internal ionisation and to the emission of a photoelectron (see Fig. 13.2). 

Ig and Ig are the respective nuclear spin quantum numbers of the excited and ground states of the nucleus and a is the internal conversion coefficient, i.e., a is the ratio of the number of conversion electrons to the number of y-ray photons emitted from a Mbssbauer atom. For a to be large we need Ey and a to be small. Oq must also be large compared with the cross-section for other absorption processes, e.g., photoelectric. 

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