Vibronic spectra ofGd3+in metaphosphate glasses: Comparison with Raman and infrared spectra

Vibronic sidebands associated with the ${}_{}{}^6{}_{}{}^{}P_{\frac{7}{2}}^{}{}_{}{}^{}\to {}_{}{}^8{}_{}{}^{}S_{\frac{7}{2}}^{}{}_{}{}^{}$ transition of ${\mathrm{Gd}}^{3+}$ -doped metaphosphate glasses are observed using line-narrowed fluorescence techniques. Glasses having metal cations of different mass and charge (La,Al,Mg,Ba) are examined. Vibronic spectra, which probe vibrations about the rare-earth element site, are compared with polarized Raman scattering data and the infrared dielectric constant obtained from near-normal reflectance measurements. Results indicate that in metaphosphate glasses vibronic selection rules are similar to $\mathrm{HV}$ Raman selection rules. The wavelengths and relative intensities of peaks in the high-frequency portion of the vibronic spectra change with respect to corresponding peaks in the Raman spectra when the mass and/or charge of ${\mathrm{Gd}}^{3+}$ differs significantly from that of the metal cation.