Luminescence quenching mechanism for microheterogeneous systems

Abstract

Determining quenching mechanisms for luminescent species
\nadsorbed or bound to a variety of heterogeneous systems
\n(e.g., silicas, organic, inorganic, and biopolymers) is quite difficult In the absence of detailed information on system heterogeneity. A method for assessing the relative contributions of static and dynamic quenching in heterogeneous systems is presented. While the method does not provide direct information on the details of system heterogeneity, it requires no a priori information on the nature of the heterogeneity. This approach is based on a comparison of intensity quenching data with lifetime quenching data using a preexponential weighted lifetime, τ_m. τ_m is calculated by fitting the observed decay curves to a sum of a relatively small number (2-4) of exponentials. For time-correlated single-photon
\ncounting the parameters obtained from a statistically acceptable fit can be used to accurately estimate τ_m, even
\nthough the computed model may bear no resemblance to the
\ntrue decay kinetics. Simulations confirm that the method
\nworks for a wide range of heterogeneous systems. The
\ntechnique is applied to oxygen quenching of a luminescent
\nmetal complex on a silica surface.