Resonant emission spectra of ${\mathrm{YF}}_3,$ ${\mathrm{YCl}}_3,$ ${\mathrm{Y}}_2{\mathrm{O}}_3$ and Y-metal in the Y $L_{\mathrm{III}}$ absorption region

Resonant emission spectra of ${\mathrm{YF}}_3,$ ${\mathrm{YCl}}_3,$ ${\mathrm{Y}}_2{\mathrm{O}}_3,$ and Y-metal are observed across Y $L_{\mathrm{III}}$ 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 $L_{\alpha }$ 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 $L_{\alpha }$ emission peak is observed. Obtained spectra are decomposed into Raman and normal $L_{\alpha }$ 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 $L_{\alpha }$ emission peak is estimated and discussed in relation of the electronic structure of these compounds.