Lanthanide Luminescence in Solids

Abstract

A tutorial introduction to the spectra of lanthanide ions is given. The chapter begins with a brief comparison of luminescence of lanthanide ions (Ln 3+ ) in the solid, liquid, and gas phases. Then a description of the importance of nonradiative versus radiative processes is made. The various types of transition of lanthanide ions encountered are then introduced: 4f N -4f N ; 4f N -4f NÀ1 5d; charge transfer; host band-to-band; and defect site or impurity transitions. Reference is briefly made to the spectra of dipositive ions. The luminescence of lanthanide ions in non-lanthanide hosts is examined, and the importance of locating the relative positions of Ln 3+ energy levels relative to the host band gap is stressed. Some of the various upconversion phenomena, including second harmonic generation, twophoton absorption, ground state/excited state absorption, energy transfer upconversion, and photon avalanche, are then described with reference to Ln 3+ and Ln 3+ -TM n+ (transition metal) systems. The experimental distinctions of which particular process is operative in a given system are explained by considering the power, concentration, and lifetime dependences, and the upconversion excitation spectrum. Some applications of lanthanide luminescence are briefly reviewed and a mention of the luminescence in nanomaterials is also included.

Luminescent properties of Eu3+ ions in CaB6O10 polycrystals

“…The number of the 5 D 0 -7 F J europium (III) peaks indicates that the site symmetry of the Eu 3 þ is a monoclinic C s , C 2 or triclinic C 1 [12], which is consistent with the crystallographic data, indicating that Ca 2 þ ions in this structure possess the triclinic C 1 symmetry [4].…”

Determination of the Eu 3+ ion local structure in oxide and fluoride crystals

“…However, according to the levels diagram [28], and the emission spectrum of the Eu 3+ ion in BaLiF 3 [25], the local symmetry of the luminescent site cannot be a C 2h . In such symmetry the crystal field effect is sufficient to completely remove the degeneracy of the 7 F 1 multiplet.…”

Photophysical studies of highly luminescent europium(III) and terbium(III) complexes functionalized with amino and mercapto groups

“…For the most part of the complexes the intensity of the excitation bands assigned to ligands transitions are higher than the 4f-4f ones. The emission spectra of europium(III) complexes provide a lot of structural information and the point symmetry (approximated) around the europium(III) ion [26]. For all europium (III) complexes emission spectra, Fig.…”

“…3(b) and (d), the expected transitions 5 D 0 -7 F J , (J¼0; 1; 2; 3 and 4) are seen, and for all of them, the 5 D 0 -7 F 2 transitions are more intense than the 5 D 0 -7 F 1 ones, meaning that the forced electric dipole and the dynamic coupling mechanisms are predominant in relation to the magnetic dipole one because the europium(III) ion is located in a low micro-symmetry site. For europium(III) emission spectrum the number of lines for each transition may be correlated with the local point symmetry [26]. The [Eu(tta) 3 (H 2 O) 2 ] shows the highest number of splittings for each 5 D 0 -7 F J transitions in the emission spectra followed by the complexes derivate from the aba -ligand ([Eu(aba) 3 (L)]; L¼H 2 O, dmf or phen).…”