8 Photophysical properties and characterisation of lanthanoids

The special photophysical properties of the lanthanoids are among the most fascinating characteristics of these elements and are the basis of many technological applications. The fundamental understanding of these properties is crucial for a further improvement of lanthanoid luminophores. At the same time, the photophysical characterisation of lanthanoid coordination compounds can help to understand their overall properties, such as their composition in solution. This chapter starts with a short introduction to the basic photophysical properties of trivalent lanthanoids and the most important implications for the design of luminescent lanthanoid coordination compounds. Afterwards, the established standard techniques for the characterisation of lanthanoid luminophores are introduced with concrete advice for the successful performance of the experiments. In the last section of the chapter short introductions to two emergent fields of study are given: The circularly polarised luminescence (CPL) of lanthanoids and energy transfer processes between lanthanoids.