Deglitching procedure for XAFS.

A computer program for eliminating artifacts such as glitches and Bragg peaks of the polarized XAFS spectra is presented. It permits to easily locate and to eliminate from the EXAFS spectra the additional signals originated from the Bragg scattering by crystalline samples. The test of the procedure on the spectra with specially introduced artifacts and on the experimental polarized XAFS spectra showed its high effectiveness.

The temperature dependence for the third shell's Fourier-peak of Nb-EXAFS in KNbO3 as additional source of information on the local atomic structure.

The information on the structure of tetragonal KNbO3 is extracted from the temperature dependence of the third shell's Fourier-peak of Nb-EXAFS. It is shown that this dependence can be explained by two effects: 1) rigid rotations of the O6-octahedron and 2) increase of the third shell's DW-parameter. However, diffraction data on the temperature dependence of the DW-parameter permit us to conclude that the last effect only is sufficient and the O6-octahedron rotation doesn't occur in the high-temperature phases of KNbO3. Using EXAFS it is revealed that in the neighboring cells Nb-atoms are parallel shifted closely to [211] direction in tetragonal phase.