Berlin 2014 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 18: Laser development and applications III

Q 18.6: Vortrag

Dienstag, 18. März 2014, 11:45–12:00, DO26 207

Absolute Photoluminescence Quantum Yield of Hexagonal β-NaYF4:Tm3+, Yb3+ Upconversion Nanoparticles — •Marco Kraft¹, Martin Kaiser¹, Christian Würth¹, Ute Resch-Genger¹, and Tero Soukka² — ¹BAM Bundesanstalt für Materialforschung und -prüfung, Richard-Willstätter-Str. 11, 12489 Berlin — ²Department of Biotechnology, University of Turku, Tykistökatu 6A, FI-20520 Turku, Finland

Hexagonal β-NaYF4 doped with Yb3+ and Tm3+ is an efficient up-conversion (UC) phosphor to convert 976 nm to 800 nm and 480 nm light. The rational design of nm-sized UC particles and their performance evaluation as well as the comparison of different materials require reliable spectroscopic tools for the characterization of the signal-relevant optical properties of these materials like the absolute quantum yield (QY). The QY of these particles in the solid state or in dispersion can be measured with high precision only absolutely.

This absolute measurement of UC QY still presents a considerable challenge due to the low absorption coefficient of these materials and the power density dependence of QY. In this respect, we present a custom-designed integration sphere setup equipped with a power-stabilized 976 nm-laser diode for spectrally resolved and power density-dependent measurements of absolute fluorescence. The UC QY and the photonic nature of the different UC emission bands are studied by varying the excitation power density. Furthermore, time-resolved measurements are performed to correlate the UC QY with the luminescence lifetimes of the different emission bands.