Dokument-ID Dokumenttyp Autoren/innen Persönliche Herausgeber/innen Haupttitel Abstract Auflage Verlagsort Verlag Herausgeber (Institution) Erscheinungsjahr Titel des übergeordneten Werkes Jahrgang/Band ISBN Veranstaltung Veranstaltungsort Beginndatum der Veranstaltung Enddatum der Veranstaltung Ausgabe/Heft Erste Seite Letzte Seite URN DOI Lizenz Datum der Freischaltung OPUS4-50698 Vortrag Frenzel, Florian Spectroscopic study of plasmon enhanced UPCON luminescence of silica-metal core-shell nanocomposites - status report The presentation focuses on the current state of the optical spectroscopic studies on plasmon enhanced upconversion luminescent processes of silica-metal core-shell nanocomposites. A general introduction of the upconversion process, the theoretical basis of plasmonic enhancement, the theoretical requirements in regard to NP architecture for plasmon enhanced UC will be outlined. The first proof-of-concept measurements show the difficulty in realization the theoretical measurement parameters in laboratory conditions and underline the need for shifting the experiments to single particle level." 2017 Gruppenseminar der Nanooptik an der HU Berlin, Prof. Benson, Institut für Physik, Raum 1‘404 Berlin, Germany 09.05.2017 2020-04-27 OPUS4-46370 Zeitschriftenartikel Meijer, M. S.; Rojas-Gutierrez, P. A.; Busko, D.; Howard, I. A.; Frenzel, Florian; Würth, Christian; Resch-Genger, Ute; Richards, B. S.; Turshatov, A.; Capobianco, J. A.; Bonnet, S. Absolute upconversion quantum yields of blue-emitting LiYF4:Yb3+,Tm3+ upconverting nanoparticles The upconversion quantum yield (QY) is an essential parameter for the characterization of the optical performance of lanthanoid-doped upconverting nanoparticles (UCNPs). Despite its nonlinear dependence on excitation power density, it is typically reported only as a single number. Here, we present the first measurement of absolute upconversion quantum yields of the individual emission bands of blue light-emitting LiYF4:Yb3+,Tm3+ UCNPs in toluene. Reporting the quantum yields for the individual emission bands is required for assessing the usability of UCNPs in various applications that require upconverted light of different wavelengths, such as bioimaging, photocatalysis and phototherapy. Here, the reliability of the QY measurements is demonstrated by studying the same batch of UCNPs in three different research groups. The results show that whereas the total upconversion quantum yield of these UCNPs is quite high - typically 0.02 at a power density of 5 W/cm2 — most of the upconverted photon flux is emitted in the 794 nm upconversion band, while the blue emission band at 480 nm is very weak, with a much lower quantum yield of 6 times 10^5 at 5 W/cm2. Overall, although the total upconversion quantum yield of LiYF4:Yb3+,Tm3+ UCNPs seems satisfying, notably for NIR bioimaging, blue-light demanding phototherapy applications will require better-performing UCNPs with higher blue light upconversion quantum yields. Royal Society of Chemistry 2018 Physical chemistry, chemical physics : PCCP 20 35 22556 22562 10.1039/c8cp03935f 2018-10-25