Cluster Size Effect of X-Ray Fluorescence Hologram Simulation Using Sr_0.95La_0.05TiO₃

Abstract

We simulated La L_γ1 X-ray fluorescence holography (La L_γ1 XFH) on a spherical cluster model of Sr_0.95La_0.05TiO₃. As the radius of the model r_c increased from 10 Å to 200 Å, the simulated hologram pattern became finer and sharper. The X-ray standing wave lines in the simulated hologram of the model with r_c = 200 Å reproduced those in the experimentally obtained hologram well. Because the X-ray fluorescence hologram is defined as a function on a spherical surface, we estimate the fineness of the pattern by calculating the power spectrum with the spherical harmonics transform. The power spectrum of the holographic oscillations of the experimentally obtained hologram shows no cutoff below the Nyquist frequency. The power spectra of the models with 60 Å ≤ r_c ≤ 200 Å do not show cutoffs either. These indicate that the radius of the cluster model r_c should be set at least 200 Å to reproduce the experimentally obtained hologram of Sr_0.95La_0.05TiO₃.