On the method of calibration of the energy dispersive EXAFS beamline at Indus-2 and fitting theoretical model to the EXAFS spectrum

Abstract

A procedure for calibration of the recently developed energy dispersive EXAFS beamline at the Indus-2 synchrotron source at RRCAT, Indore, India has been described. The procedure involves recording of absorption spectra of two standard samples, whose absorption edge energies are well-established. Two methods have been considered for calibration. In the first method, the position of the first maximum of the derivative of absorption curve is taken as the position of the edge energy. In the second method, the position of the point at half edge step in the absorption curve is taken as the position of the edge energy. It has been shown that only the first method gives same values of dispersion even when the beam current is varied and should be used for calibrating the experimental spectra. Further, it is recommended that the performance of the beamline for a particular setting should be checked by recording and analysing EXAFS of a standard. Hence, the procedure for analysis and extracting information about the various parameters that can be determined by fitting the EXAFS data with a theoretical model has also been described, by taking the example of K-absorption spectra of copper metal foil recorded on this beamline.

An X‐ray absorption spectroscopic study of carbon monoxide‐adsorbed Cu surface

“…The actual d value is αd eff = d eff + Δ d , where d eff is the theoretical half path length in the fitting model, and α is the lattice expansion coefficient. The measured d of bare Cu is 2.5389 Å, which is 0.01 Å smaller than the report for Cu metal foil . Similar contractions of atomic bonding distance were also observed and theoretically predicted as the surface effect becomes dominant .…”

X-ray absorption spectroscopy based investigation of local structure in yttria stabilized zirconia nanoparticles generated by laser evaporation method: Effect of pulsed vs CW mode of laser operation

“…A metal film of zirconium and commercial Y 2 O 3 powders were used for calibration of Zr and Y edges respectively. Energy selection was accomplished by using a double-crystal monochromator and X-ray intensity was measured before and after the sample using ionization chambers filled with optimal gas pressure and mixtures [30][31][32][33].…”

X-rayKabsorption spectral studies of copper (II) hydroxamic acid mixed ligand complexes

“…Then, a procedure for energy calibration for that particular setting has to be followed. The various aspects of the calibration and the procedure to be followed on this beamline have been given by Gaur et al …”