Publisher Summary The intensities of intraconfigurational f–f transitions are reviewed in the chapter The chapter presents the transition mechanisms for lanthanide ions—namely, the magnetic dipole transition, the induced electric dipole transition, and the electric quadrupole transition It discusses the way experimental intensities can be determined from the spectra The chapter also focuses on the expression of the dipole strength and the oscillator strength in oriented and in randomly-oriented systems Correction factors for lanthanide ions in a dielectric medium are described in the chapter Although only a few magnetic dipole transitions exist for the trivalent lanthanide ions, magnetic dipole transitions are of interest, because their intensities are in a first approximation independent of the ligand environment and can, thus, be used as intensity standards The intensity of a magnetic dipole transition can be calculated exactly, provided that suitable wavefunctions are available These wavefunctions can be obtained from diagonalization of the energy matrix

Chapter 167 Spectral intensities of f-f transitions

50th anniversary of the Judd–Ofelt theory: An experimentalist's view of the formalism and its application

The upconversion of infrared radiation into green and red fluorescence has been studied for Er3+ and Yb3+ ions in BaF2/ThF4 fluoride glass over a wide temperature range and several dopant concentrations. At room temperature an upconversion efficiency of 3.3×10−5 has been obtained for the green emission from the glass with 1 mol % ErF3 and 19 mol % YbF3 pumped by 973‐nm radiation with intensity of 16.5 mW/cm2. For an absorbed intensity of 10 W/cm2 the efficiency for green upconversion emission is predicted to be 2%. Radiative transition rates for the excited states of Er3+ were calculated using Judd–Ofelt theory and intensity parameters obtained from measured integrated absorption coefficients. The calculated values of the multiphonon relaxation and the upconversion fluorescence intensity, obtained from the rate equation model of Wright, are discussed in light of the experimental results.

Multiphonon relaxation and infrared‐to‐visible conversion of Er3+ and Yb3+ ions in barium‐thorium fluoride glass

An investigation has been made of the radiative and non-radiative properties of the well known ZBLAN glass composition doped with individual rare earth elements (Pr3+, Nd3+, Dy3+, Ho3+, Er3+ and Tm3+) at levels between 0.1 and 4 mol%. The optical absorption and fluorescence spectra of the samples were measured and also the lifetimes for some transitions. Using the Judd-Ofelt model, the radiative decay rates between the different levels, the lifetimes and the branching ratios were calculated. These results and comparison of calculated and measured lifetimes are discussed with respect to radiative and non-radiative rates and quantum efficiencies. The multiphonon rates below 3200 cm−1 are found to be less in ZBLAN than in other host materials (ZBLA, SiO2, YAG).

Optical properties of rare earth-doped ZBLAN glasses

Germanotellurite glasses in the compositions of TeO 2 –GeO 2 –ZnO–Y 2 O 3 –Na 2 O–Er 2 O 3 were prepared by various conditions. The effect of the composition and various drying procedures on the content and the vibration frequency of OH groups was investigated. Among various drying techniques for removing the OH groups, it has been found that bubbling a mixture of dry oxygen gas and carbon tetrachloride shows significant effect on removing OH groups. Also the quenching effect of OH upon the lifetimes of the 4 I 11/2 and 4 I 13/2 levels of Er 3+ in germanotellurite glasses was slight with low Er 3+ and OH content.

Hydroxyl groups in erbium-doped germanotellurite glasses

Optical absorption and emission spectra are presented for Pr 3+ ions in fluorozirconate (ZBLA) glass. The measured oscillator strengths and radiative rates for several transitions are compared with calculated values. Radiative transition rates for the excited states are determined by using the Judd-Ofelt theory. Energy transfer effects account for the nonradiative transitions. Although the Judd-Ofelt analysis does not yield the same excellent consistency for oscillator strengths and branching ratios for Pr 3+ as for Er 3+ and Ho 3+ , the experimental observations are consistent with the Judd-Ofelt calculations and the multiphonon emission rates predicted by the phenomenological energy-gap law. The crystallization of ZBLA glass also was studied, using Pr 3+ ions as probes.

Optical transitions of Pr3+ ions in fluorozirconate glass

The effect of 1.7 MeV electrons on the coloration of Yb 3+ doped BaF 2 /ThF 4 base fluoride glasses has been investigated. Irradiation at 80 K produces a prominent absorption band at 302 nm. At room temperature, the radiation induced absorption is quite small in these glasses when compared with the absorption in fluorizirconate glasses. The photochemical damage mechanism is dominant. The optical absorption and emission spectra as well as the fluorescence lifetime of Yb 3+ ion transitions have been measured. The measured lifetimes are compared with the calculated radiative lifetimes.

Radiation effects and optical transitions in yb3+ doped barium-thorium fluoride glass

The effect of 1.7 MeV electrons on the coloration of fluorozirconate (ZBL) and fluorohafnate (HBL) glasses has been investigated. Irradiation can produce intense broad absorption bands at 325 nm and 253 nm in the glasses. However, the size and shape of the absorption bands in zirconate-based glass (ZBLA) which has Al3+ ions as network stabilizers is different from those in ZBL and HBL glass. The optical absorption bands due to self-trapped hole centers can be assigned from dichroic absorption measurements. It appears that the radiolysis damage mechanism may contribute to the coloration of these fluoride glasses.

W.A. Sibley

Papers

Optical transitions of Pr3+ ions in fluorozirconate glass

Radiation effects and optical transitions in yb3+ doped barium-thorium fluoride glass

Optical absorption study on radiation damage in fluoride glasses