Faculté des sciences

Wavelet investigation of La0.5Ca0.5CoO3−δ x-ray absorption data

Sahnoun, Mohammed ; Daul, Claude A. ; Haas, O.

In: Journal of Applied Physics, 2007, vol. 101, no. 1, p. 014911

Morlet wavelet transformation was used to analyze the Co K-edge extended x-ray absorption spectrum of La0.5Ca0.5CoO3−δ. Due to recent success in wavelet analysis of extended x-ray absorption fine structure (EXAFS) data we hoped that the Co–La scattering path could be separated from the Co–Ca scattering path in the EXAFS spectrum of... Plus

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    Summary
    Morlet wavelet transformation was used to analyze the Co K-edge extended x-ray absorption spectrum of La0.5Ca0.5CoO3−δ. Due to recent success in wavelet analysis of extended x-ray absorption fine structure (EXAFS) data we hoped that the Co–La scattering path could be separated from the Co–Ca scattering path in the EXAFS spectrum of La0.5Ca0.5CoO3−δ. The result showed a certain resolution of the wavelet transformed spectrum in the k space. Using theoretical scattering functions of the individual scattering paths calculated with ab initio multiple scattering codes (FEFF), it was possible to assign some maxima in the wavelet transformation EXAFS spectrum. The Co–La scattering path could be identified, but no additional information about the Co–Ca scattering function was obtained. A detailed analysis of the theoretical Co–La and Co–Ca scattering functions revealed that the two scattering functions overlap considerably in k space and have almost the same frequency. Morlet wavelet transformation of the sum of the two theoretical scattering functions did not allow a satisfactory separation of the two scattering functions. This separation is probably only possible with wavelets, which mimic the fundamental properties of the real scattering function more accurately.