The principles of fluorescence spectroscopy are by now well established, and, after a rather lengthy gestation period, the technique is now routinely applied to a broad spectrum of problems, ranging from mechanistic photo- chemistry to chemical analyses in biomedical and environmental systems to probes of structure and function in biological macromolecules. Phosphor- escence spectrometry and chemiluminescence are also well-known tech- niques; they are somewhat less well established than fluorescence (at least in analytical chemistry), but they too are receiving greatly increased appli- cation...