The Measurement and Analysis of Heterogeneous Emissions by Multifrequency Phase and Modulation Fluorometry

Abstract During the last few decades fluorescence spectroscopy has developed into an important and widely used technique in the physical, chemical, and biological sciences. The increasing sophistication of theory and methodology has permitted us to apply fluorescence techniques profitably to a variety of complex problems. A fundamental consideration in the spectroscopic analysis of any system is the degree of sample heterogeneity. We wish to know, for example, if the teterogeneity arises from a melange of fluorophores (this condition often reduces to the question of sample purity) as a consequence of solvent-fluorophore interactions or from the fluorophore per se. An exact quantitation of the nature and extent of the heterogeneity may be critical to our understanding of the origins of that phenomenon. These data have important implications whether the desired information concerns a compositional description for analytical purposes or whether the fluorophore is designed to probe the molecular environment.