A Comparative Study of the Methods of Speciation Using X-ray Absorption Fine Structure

Abstract

Determination of the chemical forms along with the relative quantity of the dierent species in a given sample, termed as speciation, can be done by analyzing X-ray absorption ne structure spectra. The dierent methods that can be used for speciation are: principal component analysis, target transformation, methods based on derivative spectra, method based on the relative position of the absorption edge, residual phase analysis, normalized dierence absorption edge spectra analysis and linear combination tting. An attempt has been made to make a comparative study of these dierent methods of speciation by recording the X-ray absorption ne structure at the copper K-edge in a mixture having cuprous oxide and cupric oxide in a specic ratio. The X-ray absorption ne structure spectra of the two oxides have also been recorded separately and the dierent characteristic X-ray absorption near edge structure features have been identied and their origins have been discussed. Speciation of the mixture has been done using these dierent methods and the results obtained have been compared and discussed.

XAFS structural characterization of Cu vapour derived catalysts supported on poly‐4‐vinylpyridine and carbon

“…The co-presence of Cu 2 O and CuO, with different percentages and in particular with a relevant presence of Cu 2 O, can be identified in the near edge region by a lowering of the intensity of the absorption peak B. [42] This effect can clearly be observed in Figs 2 and 3. It is well known that also NPs size effects can induce changes in the near edge region, but we surely cannot exclude that, the observed lowering of the intensity of the peak B, does not include also a contribution coming from the presence of a CuO surface layer.…”

EXAFS Study of the Local Order in Cu2ZnSn(SxSe1–x)4 Alloys

“…Referring to the observed systematic changes of the spectra with composition we made an attempt to represent the EXAFS oscillations of the alloys as a weighted sum of the spectra for the end compounds: CZTS and CZTSe. We applied the LCF method that is used to determine relative amount of known constituents in complex systems . The LCF fitting has been done using the Cu, Zn and Sn EXAFS oscillations χ(k) in the k ‐space range (2.0–12.0) Å −1 for CZTS and CZTSe compounds: …”

“…We applied the LCF method that is used to determine relative amount of known constituents in complex systems. [24,25] The LCF fitting has been done using the Cu, Zn and Sn EXAFS oscillations χ(k) in the k-space range (2.0-12.0) ÅÀ 1 for CZTS and CZTSe compounds:…”

Nature and reactivity of layered double hydroxides formed by coprecipitating Mg, Al and As(V): Effect of arsenic concentration, pH, and aging

“…LCF of As/Mg-Al-LDH and HNa 2 AsO 4 As K-edge XANES to model the coprecipitated sample spectra (results listed in Table 2) also indicated that all samples primarily consisted of one component, As/Mg-Al-LDH. In addition, the relative amount of As/Mg-Al-LDH increased from the samples aged for 5d to samples aged for 180d [36]. 10 Being the major component of all the investigated samples, the As/MgAl-LDH EXAFS spectrum was fit to the EXAFS equation to characterise its coordination structure.…”