Spectroscopy in the Visible and Near-Visible Spectral Range

Abstract

The spectral range where spectroscopy has been used for the longest time and where it is still most often applied is the visible and near-visible. In this range spectroscopy can be performed with the naked eye without any scientific instruments. However, even here, highly sophisticated experimental techniques have been applied and have revealed many details about electronic structures. In the present chapter we review first some details about the quantum-mechanical description of optical absorption and then apply this formalism to absorption in systems with extended states such as semiconductors and to systems with localized states like color centers, defect states and transitions in molecular crystals. An introduction to luminescence processes is presented in the last section. More details about the quantum-mechanical formalisms used can be found in Appendices F.1 to F.3.