Applications and limitations of uranyl ion as a photophysical probe

Uranyl ion has a long-lived luminescent excited state, which can be used as a probe for the aggregation behaviour in a variety of surfactant and polymeric systems. The general spectroscopy and photophysics of this species are discussed, and the applications to specific micellar, microemulsion, vesicular and liquid crystalline systems presented. It is shown that both dynamic and structural information can be obtained from spectral and kinetic data. Examples of applications of uranyl probe studies to technologically important mesoscopic and mesoporous systems involving metal oxides, or their salts, and to humic acids and soils will also be reviewed. Emphasis will be given to both the advantages and restrictions on the use of this useful photophysical probe.