This volume of the Handbook examines the widely varying range of rare-earth-element involvement on this planet.

Chapter one is a summary of recent developments in the use of chemical shifts included in reagents of paramagnetic lanthanide complexes. One of the more important developments that has evolved from the research in this area is the use of lanthanide complexes in magnetic resonance imaging (MRI) in the medical field.

The following chapter discusses the theory and application of the consequences of antenna-to-ion energy transfer and its relationship to supramolecular chemistry. Applications of these complexes in fluorimmunoassays and DNA hybridization assays are also discussed.

The rationalization of crystal field parametrization is considered in a pedagogical context in the next chapter, thus continuing an ongoing treatment of the spectroscopic properties of the rare-earth elements in the Handbook. The authors emphasize the symmetry aspects of the crystal field and the parametrization of the energy level scheme.

In the next chapter the authors present a systematic and encyclopedic discussion on the phosphides of the binary, ternary and quaternary rare earths. Their coverage includes preparation, phase diagrams, structure, as well as chemical and physical properties. The crystallochemical regularities, the nature of the interaction between components in ternary systems, and structural relationships also constitute important aspects of this review.

Metal-containing vapor species such as the simple rare-earth halide vapors and vapor complexes MX-RX3 and MX2-RX3 are finding increasing use in halogen lamps and energy storage media for high-power laser systems and for development of recycling/separation processes. This process is considered in the next chapter, in which particular attention is paid to thermodynamic and structural trends, and to characteristic experimental techniques such as absorption and fluorescence spectroscopy.

The final chapter is a review of the lanthanide composition of the oceans and the processes that control the lanthanide distribution. Particular attention is given to research on the lanthanide geochemistry of marine hydrothermal vent systems.