The fluorescence probe technique has been used to study micelles of anionic, cationic and non-ionic surfactants. The solute was pyrene. The formation of a fluorescent excited dimer (excimer) by pyrene means that this probe can be used not only to explore intramicellar kinetics, but also to monitor the manner in which micelles change their size. The change in size of ionic surfactants with electrolyte concentration and of non-ionic surfactants with temperature is explored. We have developed a simple method involving the effect of oxygen (in air) on the fluorescence spectrum for detecting statistical distribution effects in the solubilization of pyrene in micelles. The combination of fluorescence spectra with time-dependent fluorescence intensity (fluorescence 'decay') allows a full analysis.

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Fluorescence lifetimes of low pressure gaseous systems are necessary for the understanding of electronic relaxation in an isolated molecule. A detailed experimental and theoretical analysis of the technique of single photon decay spectroscopy is presented. This includes the construction of nanosecond light sources, the detection and timing of single photons, and a statistical analysis of the results. Standards for time calibration and detection sensitivity are suggested. ��� This paper provides the basis for subsequent studies of the fluorescence decay of aromatic vapours.

The excited acid-base reactions of 1-naphthol and pyren-1-amine have been studied in sodium dodecyl sulphate surfactant micelles. These molecules which show complete equilibration for excited state reactions in water show only partial equilibration in micelles (2-naphthol goes from partial equilibration to complete lack of reaction). It is believed that this is a micellar viscosity effect.

β-Methoxynaphthalene in solution shows excimer fluorescence and also forms a stable dimeric photoproduct on prolonged irradiation. Both these processes were examined in detail for a set of related compounds and the nature of the photoproducts was investigated.