Chapter 8 - Spectroscopy of Lanthanide Complexes

Abstract

The lanthanide series of elements differ from the transition metal series in that 4f shell inner electrons are shielded by the 5s2, 5p6 closed shells. Consequently f shell electrons interact much less strongly with their environment than the d electrons in the transition series. The electronic structure of the f" lanthanide ion is dominated by many different interactions than for more familiar d" transition metal ions. Furthermore, this chapter turns to the discussion of lanthanide crystal field theory given by Bethe in 1929, which showed that open-shell energy levels in a crystalline environment could be associated with the irreducible representation labels of the site point group. Crystal-field levels of rare earth salts were determined by spectroscopy. Electronic energy levels for free trivalent rare earth ions must be identified before analyzing the spectra of rare earths in crystals. Crystal field levels in rare earth metals were determined by measurements of various properties: specific heat, Van Vleck susceptibility, magnetization in high magnetic fields, paramagnetic resonance, Mössbauer effect, and inelastic neutron scattering.