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Humboldt-Universität zu Berlin - Mathematisch-Naturwissen­schaft­liche Fakultät - Nanooptik

Humboldt-Universität zu Berlin | Mathematisch-Naturwissen­schaft­liche Fakultät | Institut für Physik | Nanooptik | Publications | Quantitative Measurements of the pH-Sensitive Quantum Yield of Fluorophores in Mesoporous Silica Thin Films Using a Drexhage-Type Experiment

Ersan Özelci, Bastian Rühle, Florian Weigert, Boaz Lubotzky, Günter Kewes, Ute Resch-Genger, and Oliver Benson (2019)

Quantitative Measurements of the pH-Sensitive Quantum Yield of Fluorophores in Mesoporous Silica Thin Films Using a Drexhage-Type Experiment

J. Phys. Chem. C, 123(33):20468-20475.

The photoluminescence quantum yield characterizes the performance of emitters for applications in optical devices, as reporters or probes in material and analytical sciences, and for sensing applications. Quantum yield measurements are challenging for luminescent molecules and nanocrystals immobilized in thin films for many sensor applications, particularly if spatially resolved quantitative luminescence information is desired. We show here that a Drexhage-type experiment, where a silver-coated millimeter-sized sphere is used to modify the local density of states, can provide an elegant approach to counter this challenge. As a representative example of the potential of this method, we measure the pH-dependent photoluminescence quantum yield of fluorescein isothiocyanate bound to a thin mesoporous silica film. The results were compared with those of the studies on the pH dependence of the same dye in solution. We found that our approach can link single fluorophore studies to ensemble measurements and pave the way for the spatially resolved fluorescence measurements of ultralow concentrations of emitters utilized as optically active elements and reporters in thin sensor films or incorporated into membranes.