Resonant emission spectra of YF 3 , YCl 3 , Y 2 O 3 , and Y-metal are observed across Y L III absorption threshold. When the incident photon energy is below the absorption threshold, only Raman scattering component is observed. The Raman-scattering component has a two-peak structure, main and subpeaks. Above the absorption threshold, both Raman and normal L ␣ emission peaks are observed in insulator samples. The intensities of the Raman peak are resonantly enhanced as the incident photon energy reaches the absorption edge. On the other hand, in Y metal, only normal L ␣ emission peak is observed. Obtained spectra are decomposed into Raman and normal L ␣ emission peaks by line-shape analysis. The results are compared with theoretically calculated ones and are discussed the relaxation of core-electron excitation processes. The onset energy of the normal L ␣ emission peak is estimated and discussed in relation of the electronic structure of these compounds.
The dielectric constant ϵ′(ω, T), ϵ″(ω, T) and the electric conductivity σ(ω, T) of Bi2WO6 single crystals are measured in the temperature range from 350 to 4.2 K and at frequencies from 20 Hz to 1 MHz. The anomalous temperature dependences of σ, ϵ′, and ϵ″, and the intensity of X‐ray diffraction along the b‐axis are observed at about 15 °C. These anomalies correspond to a first order phase transition related with the impurity conduction and with the soft phonon. From the temperature dependence of x = 1 − 4/ln (νph/ω) on ac hopping conductivity σ(ω) ∝ ωs and dielectric constant ϵ″(ω) ∝ ωs−1, the softening of phonon is confirmed at Tc.
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