Determination of minor components in mixtures using EXAFS

An EXAFS spectrum, obtained by taking the difference between a weighted absorptivity spectrum of a known compound and that of a mixture containing this compound, contained information mainly on the remaining phase(s) in the mixture. The optimum weighting factor was that which gave the minimum value of the definite integral of the radial distribution function (RDF). The efficacy of this technique was demonstrated by the easy identification of Cu₂O, after removal of the CuO contribution, from the spectrum of a mixture of 5% Cu₂O in a ca. 1 + 1 mixture of CuO and ZnO. The method was also used to probe the minor component(s) of a CuO and ZnO calcined catalyst precursor; these showed features consistent with copper dissolved in the ZnO lattice.