Spectroscopy heavy lanthanide metals

At the present time the electron-spectroscopic manifestations of 4f-hybridization in heavy lanthanide materials are scarce. (The so-called valence fluctuating compounds containing the elements Sm, Eu, Tm or Yb are discarded here (see section 7.3).) Nevertheless, indications for a coupling of the f states with band states have been found in materials where the Eu atoms, according to Mossbauer spectroscopy and the magnetic susceptibility, are in the divalent 4f configuration. The XPS 3d core level spectra of a few systems, like Eu metal, EuAlj, EuCuj, EuAgj (Schneider... 

Three of the chapters in this volume deal with various aspects of the magnetic behaviors of the lanthanide metals and some of their compounds, while the fourth is concerned with the photoelectron spectroscopy of the anomalous f (heavy fermion) systems in cerium and uranium compounds. 

Relativistic and electron correlation effects play an important role in the electronic structure of molecules containing heavy elements (main group elements, transition metals, lanthanide and actinide complexes). It is therefore mandatory to account for them in quantum mechanical methods used in theoretical chemistry, when investigating for instance the properties of heavy atoms and molecules in their excited electronic states. In this chapter we introduce the present state-of-the-art ab initio spin-orbit configuration interaction methods for relativistic electronic structure calculations. These include the various types of relativistic effective core potentials in the scalar relativistic approximation, and several methods to treat electron correlation effects and spin-orbit coupling. We discuss a selection of recent applications on the spectroscopy of gas-phase molecules and on embedded molecules in a crystal enviromnent to outline the degree of maturity of quantum chemistry methods. This also illustrates the necessity for a strong interplay between theory and experiment. 

---