Akadēmiskais centrs
Interpretations of pre-edge structures in the X-ray absorption spectra of 3d transition compounds have been in a long debate since the advent of synchrotron radiation sources: quadrupole (E2) or dipole (E1) transitions. Besides the origin of the optical process, the pre-edge structures contain various information related to material function. The dielectric properties of perovskite titanates are discussed quite often. We observed local ferroelectricity in SrTiO3 under UV irradiation or by lattice distortion in thin films. Recently, we have succeeded to observe dynamic response of BaTiO3 spectra to the applied electric field with time-resolved technique, and found that the pre-edge eg peak and the shoulder structure reflects different characteristics of dielectric properties.