Self-absorption effect revising treatment method for fluorescence EXAFS (Extended X-ray Absorption Fine Structure) data

Abstract

The invention relates to a self-absorption effect revising treatment method for fluorescence EXAFS (Extended X-ray Absorption Fine Structure) data. The self-absorption effect revising treatment method comprises the following steps: (1) obtaining structure parameters of a sample to be detected and a scattering amplitude factor and scattering amplitude of an isolated atom of a corresponding element of the sample to be detected; (2) calculating a refraction factor and an absorption factor of the isolated atom; (3) calculating refractive indexes of upper and lower films of the sample to be detected according to an X-ray waveband refractive index expression and calculating fluorescence intensity I0 (E) generated by the isolated atom by utilizing a multi-layered film fluorescence intensity calculation method; (4) initializing a revising factor alpha (E) and calculating a scattering amplitude and a scattering amplitude factor, which have fine oscillating structures and are not influenced by a self-absorption effect; (5) calculating a refraction factor and an absorption factor, which have oscillating structures; (6) utilizing the multi-layered film fluorescence intensity calculation method to calculate fluorescence intensity I (E) with an oscillating structure; (7) calculating an oscillating structure function Xcal(E) according to the I0 (E) and the I (E); and (8) judging whether the Xcal(E) meets the requirements or not. Compared with the prior art, the self-absorption effect revising treatment method for the fluorescence EXAFS data has the advantages of high reliability, wide application range and the like.

Description

technical field [0001] The invention relates to a technique for characterizing the microscopic structure of a substance by X-rays, in particular to a self-absorption effect correction processing method for fluorescence EXAFS data. Background technique [0002] X-ray Absorption Fine Structure Spectroscopy (XAFS) is based on the fine variation of the absorption coefficient of X-rays near the absorption limit of a certain atom to study the structure of condensed matter and analyze the short-range arrangement of atoms in the material. XAFS is based on the phenomenon of scattering—the scattering of photoelectrons emitted by the central absorbing atom by neighboring atoms, which reflects only the short-range ordered structural state around the absorbing atom in the material. Therefore, the theory and method of XAFS can be applied to both crystals and non-crystals, which is the biggest advantage different from crystallographic theory and structural research methods (not applicable ...

AI Technical Summary

Problems solved by technology

However, fluorescent EXAFS is easily affected by the self-absorption of the analyte, which leads to the attenuation of the EXAFS oscillation structure. If the self-absorption effect is not corrected, the analytical data will produce wrong local structures, such as coordination numbers, Debye-Waller factors, etc.

[0005] Most of the current correction methods are based on single-layer films, and there are few self-absorption correction methods for multi-layer films. Castaner and Prieto once proposed a correction method for multi-layer films, but they did not consider the incident light. The refraction and multiple reflection effects when passing through the multilayer film lead to the fact that it cannot be put into practical application; Heald et al. only corrected the data analysis results (coordination number and Debye-Waller factor)

In short, there is no convenient and universal correction method for multilayer films, which to some extent inhibits the application of fluorescence EXAFS method in the characterization of multilayer films.

Images