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Rostock 2019 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 15: Nano-Optics (Plasmonics)

Q 15.7: Talk

Monday, March 11, 2019, 15:45–16:00, S SR 112 Maschb.

Determining pH-dependent Quantum Efficiency of Emitters by Using a Metal Sphere — •Ersan Özelci1,2,3, Bastian Rühle2, Günter Kewes1, Florian Weigert2, Ute Resch-Genger2,3, and Oliver Benson1,31Humboldt-Universität zu Berlin — 2Bundesanstalt für Materialforschung und -prüfung (BAM), Berlin — 3School of Analytical Sciences Adlershof (SALSA), Berlin

One of the key spectroscopic performance parameters of molecular and nanoscale emitters is the photoluminescence quantum yield (PL-QY) that provides a direct measure for the number of emitted per absorbed photons. PL-QY can be measured by different methods in various environments and from the ensemble to the single emitter level [1-2]. A particular challenge is to determine changes of the PL-QY of emitters in liquids. Here we adapt a method based on the modification of the radiative decay of emitters by a nearby metal surface [3]. We solve the problem of fixing the emitter-surface distance by trapping organic dyes in a mesoporous silica film [4]. As organic dye we chose fluorescein, which exhibits pH-dependent fluorescence properties [5]. Our results reveal an increase in fluorescein PL-QY from about 25% to 73% with pH increasing from 5.5 to 7.5 showing the applicability of our approach for quantitative measurements.

[1] Würth et al., Anal. Bioanal. Chem. 407, 59-78 (2015). [2] Abbandonato et al., Nanoscale 10, 7147-7154 (2018). [3] Lunnemann et al., ACS Nano 7, 5984-5992 (2013). [4] Innocenzi et al., Chem. Soc. Rev. 42, 4198-4216 (2013). [5] Sjöback et al, Spectrochimica Acta Part A: Mol. Biomol. Spec. 51, 7-21 (1995).

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