Structural Evidence for Solutions from EXAFS Measurements
Physical evidence for the structure of solutions has been obtained by x-ray scattering,1,2,3,4 neutron scattering,5,6,7,8 Raman scattering,9,10 transport measurements,11 and NMR12 techniques. In addition, extended x-ray absorption fine structure spectroscopy (EXAFS spectroscopy) has been applied to this problem. It is the sensitivity to local structure that makes EXAFS especially suitable for systems like this, for which no long range order is expected. Also, the element specificity of EXAFS means that the radial distribution functions deduced from EXAFS analysis contain only the relationship between atoms of the x-ray absorbing element and its neighbors. In contrast, neutron and x-ray scattering methods result in an average correlation function for the sample as a whole, unless special techniques such as isotopic substitution in the scattering of neutrons6 or anomalous scattering of x-rays13 are employed to distinguish the correlations between specific pairs of elements.
KeywordsEXAFS Spectrum Linear Absorption Coefficient Rhodium Catalyst EXAFS Data EXAFS Spectroscopy
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