Chapter 167 Spectral intensities of f-f transitions

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.