Site-selective spectroscopy ofNd3+centers inCaF2:Nd3+andSrF2:Nd3+
| Autor: | T. P. J. Han, Glynn D. Jones, R. W. G. Syme |
|---|---|
| Rok vydání: | 1993 |
| Předmět: | |
| Zdroj: | Physical Review B. 47:14706-14723 |
| ISSN: | 1095-3795 0163-1829 |
| DOI: | 10.1103/physrevb.47.14706 |
| Popis: | Laser-selective-excitation and optical-absorption techniques have been used to establish comprehensive sets of energy levels of the ${\mathrm{F}}^{\mathrm{\ensuremath{-}}}$ and hydrogenic varieties of the tetragonal symmetry (${\mathit{C}}_{4\mathit{v}}$) centers in ${\mathrm{CaF}}_{2}$ and ${\mathrm{SrF}}_{2}$, of three multihydrogenic centers observed in both ${\mathrm{CaF}}_{2}$ and ${\mathrm{SrF}}_{2}$ and of the M, N, and M' ${\mathrm{Nd}}^{3+}$ cluster centers present in ${\mathrm{CaF}}_{2}$. Polarization of the various spectral lines of the ${\mathit{C}}_{4\mathit{v}}$ symmetry centers was used to determine the symmetry labels of all energy levels of these centers up to the $^{4}$${\mathit{F}}_{3/2}$ multiplet, for which crystal-field fits are reported. A noteworthy feature of the ${\mathrm{Nd}}^{3+}$ centers is their strong upconversion fluorescence giving a visual perception of ``white'' emission under selective laser excitation to energy levels of the $^{4}$${\mathit{G}}_{5/2}$${,}^{2}$${\mathit{G}}_{7/2}$ multiplets near 17 350 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ in the yellow. Excitation with a single frequency in this region enables observation of fluorescence from many multiplets up to the $^{4}$${\mathit{D}}_{3/2}$ multiplet near 28 200 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$. Fluorescence lifetimes for emission from the $^{4}$${\mathit{F}}_{3/2}$ multiplet are reported for several centers. The ${\mathrm{Nd}}^{3+}$ cluster centers show small splittings in their sharper transitions, which is attributed to ${\mathrm{Nd}}^{3+}$-${\mathrm{Nd}}^{3+}$ coupling effects. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|