Publisher Summary This chapter describes the symmetry aspects of the crystal field and the parametrization of the energy level scheme. It provides an overview of the experimental data of trivalent lanthanide ions doped into crystalline host matrices. The selection rules for induced electric dipole (ED) and magnetic dipole (MD) transitions for systems with even or odd numbers of f electrons in different site symmetries are presented. Methods for the assignment of crystal-field levels are discussed and the determination of phenomenological crystal-field parameters is described. Such a set of crystal-field parameters in combination with a suitable set of free-ion parameters allows calculating crystal-field energy levels and reconstructing the energy diagram of the 4fn configuration. In this way, it is not only possible to check the validity of the crystal-field model but also to get information about energy levels, which cannot be detected experimentally.

Chapter 155 Rationalization of crystal-field parametrization

The database on structural phase transitions is presented in the simple and easy accessible form of table. The symmetry changes and temperature for 3446 phase transitions and the references for each of 2242 registered crystalline materials with well defined stoichoimetry are the main data in this table. The rules for constructing and reading the database table are also presented.

Structural phase transitions in crystals. I. Database

Chiral lanthanide compounds

Polarized axial and orthoaxial luminescence spectra in the 7 Fj (J=1, 2, 3 and 4)←5 D 0 transition regions of Eu3+ in single crystals of trigonal Na3[Eu-(oxydiacetate)3]. 2NaClO4.6H2O are reported and analysed. Differential circular polarization (left-handed versus right-handed) is measured in the axial luminescence spectra of this chiral system, and differential linear polarization (σ versus π) is measured in the orthoaxial luminescence spectra. Energy level calculations as well as transition dipole strength and rotatory strength calculations are reported, and the results of these calculations are compared with experimental observation. Good agreement is achieved between the calculated and observed crystal-field splittings within 7 Fj multiplets, and satisfactory agreement is achieved for the calculated versus observed (relative) emission intensities and polarizations (σ verus π) within the 7 Fj ←5 D 0 transition regions. The chiroptical properties of the 7 F 1←5 D 0 transition are quantitatively account...

The chiroptical luminescence spectra of Eu3+ in trigonal Na3[Eu(oxydiacetate)3] . 2NaClO4 . 6H2O

Simultaneous observation of low temperature 4f–4f and 3d–3d emission spectra in a series of Cr(III)(ox)Ln(III) assembly

Polarized absorption, circular dichroism, Zeeman effect and magnetic circular dichroism spectroscopy have been used to study single crystals of trigonal trisodium praseodymium tris(oxydiacetate) di(sodium perchlorate) hexahydrate, Na3Pr(C4H4O5)3·2NaClO4·6H2O. Transitions between the crystal field levels of 3H4 and 1D2, 3P0,1,2 and 1I6 have been observed and assigned. The crystal undergoes an order–disorder phase transition between 300 and 77 K which lowers the lanthanide site symmetry to C2. The distortion caused by this phase transition is small and a crystal field calculation within the D3 point group gives a reasonable fit of the experimentally observed energy levels and supports the assignments of the crystal field components. The estimated values of the parameters are F2= 302, F4= 64.3, F6= 5.9, ζ= 723, A20= 150, A40=–1508, A43= 1128, A60= 617, A63= 308 and A66= 368 cm–1.

Asok C. Sen

Papers

Absorption, circular dichroism and magnetic circular dichroism spectra of Na3Pr(C4H4O5)3· 2NaClO4·6H2O

Optical rotatory dispersion of rare earth crystal

Magnetic-field-induced intensification of a forbidden A1 → A1 transition in the trigonal Na3Pr(C4H4O5)3·2NaClO4·6H2O crystal