Luminescence quenching mechanism for microheterogeneous systems

Abstract

Determining quenching mechanisms for luminescent species adsorbed or bound to a variety of heterogeneous systems (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, rM. rM 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 counting the parameters obtained from a statistically acceptable fit can be used to accurately estimate rM, even though the computed model may bear no resemblance to the true decay kinetics. Simulations confirm that the method works for a wide range of heterogeneous systems. The technique Is applied to oxygen quenching of a luminescent metal complex on a silica surface.

Composite particles with magnetic properties, near-infrared excitation, and far-red emission for luminescence-based oxygen sensing

“…The magnetic sensor particles showed a good response, especially at low oxygen concentrations (up to 100 hPa O 2 ). The calibration curve was fitted with a modified two-site model 37 , assuming the existence of two fractions of dye molecules within the sensor particles; one fraction is quenchable by oxygen and the other is not. A K SV value of 0.0445 hPa −1 was obtained.…”

Confined modes in photonic microtube structures

“…26,27 Thus, a description based on discrete lifetime components should only be regarded as truly representing discrete molecular states if supported by supplementary data. 28 Therefore, to gain a better insight into the spatial distribution of lifetimes, the PL dynamics were evaluated from the FLIM (fluorescence lifetime imaging microscope) images i.e. maps of two-dimensional in-plane variations of the PL decay times.…”

Indicators for optical oxygen sensors

“…1 does not adequately describe the quenching mechanism; in such cases, it is preferable to Fig. 1 Perrin-Jablonski diagram use a second equation from the so-called two-site model [35] (Eq. 2)…”