Abstract

The structure and the function of many macromolecules and organic polymers are dependent on the specific sites bound to metal ions. Metal binding in some ionic polymers is in the form of ionic clusters. The objective of our laser-induced fluorescence studies is to gain a better understanding of the structure and binding properties of these clusters by using europium ions as probes. Eu(III) has many unique spectral properties which make it a good luminescent probe of the metal binding in polymers. The energy, fluorescence quantum yield, and lifetime of the excited state of the ⁷F₀ → ⁵D₀ transition near 580 nm are very sensitive to the environment of the ions. By studying this transition in detail, it is possible to obtain unique optical information about the metal–molecule interaction. Metal binding in the perfluorosulfonate membrane, Nation (DuPont), has been studied here as function of such parameters as metal ion concentration and pH. The resulting excitation spectra show multiple peaks corresponding to different ionic environments. The results of these experiments are discussed in terms of the known macroscopic binding properties of this film.

© 1986 Optical Society of America