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Effect of Particle Size and Excitation Power Density on the Luminescence Efficiency of Upconversion Nanocrystals in Different Dispersion Media

  • Upconversion nanoparticles (UCNPs) offer new strategies for luminescence-based sensing and imaging. One of the best studied materials are ..-NaYF4 UCNPs doped with 20 % Yb3+ and 2 % Er3+, which efficiently convert 976 nm light to photons emitted at 540 nm, 655 nm, and 845 nm, respectively, reveal long luminescence lifetimes (> 100 µs), are photostable and chemically inert. Their upconversion (UC) luminescence (UCL) properties are, however, strongly influenced by particle size, surface chemistry, and microenvironment. In addition, the multiphotonic absorption processes responsible for UCL render UCL excitation power density (..) dependent. This makes quantitative UCL measurements as well as the determination of UC quantum yields (.UC) very challenging. The rational design of brighter UCNPs particle architectures and the interest in identifying optimum particle architectures for FRET-based sensing and imaging schemes, which often rely on core-only UCNPs to minimize donor-acceptorUpconversion nanoparticles (UCNPs) offer new strategies for luminescence-based sensing and imaging. One of the best studied materials are ..-NaYF4 UCNPs doped with 20 % Yb3+ and 2 % Er3+, which efficiently convert 976 nm light to photons emitted at 540 nm, 655 nm, and 845 nm, respectively, reveal long luminescence lifetimes (> 100 µs), are photostable and chemically inert. Their upconversion (UC) luminescence (UCL) properties are, however, strongly influenced by particle size, surface chemistry, and microenvironment. In addition, the multiphotonic absorption processes responsible for UCL render UCL excitation power density (..) dependent. This makes quantitative UCL measurements as well as the determination of UC quantum yields (.UC) very challenging. The rational design of brighter UCNPs particle architectures and the interest in identifying optimum particle architectures for FRET-based sensing and imaging schemes, which often rely on core-only UCNPs to minimize donor-acceptor distances, encouraged us to assess the influence of particle size and P on UCL. Here, we present the photophysical properties of a series of hexagonal NaYF4 UCNPs with sizes from 10 to 43 nm with different surface ligands dispersed in organic solvents and water studied by steady state and time-resolved fluorometry as well as quantitatively by integrating sphere spectrometry with P varied over about three orders of magnitude. Our results underline the need for really quantitative luminescence studies for mechanistic insights and the potential of high P to compensate for UCL quenching due to high energy phonons and surface effects.zeige mehrzeige weniger

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Metadaten
Autor*innen:Ute Resch-GengerORCiD
Koautor*innen:Marco Kraft, Christian Würth, Martin Kaiser, V. Muhr, T. Hirsch
Dokumenttyp:Vortrag
Veröffentlichungsform:Präsentation
Sprache:Englisch
Jahr der Erstveröffentlichung:2017
DDC-Klassifikation:Naturwissenschaften und Mathematik / Chemie / Analytische Chemie
Technik, Medizin, angewandte Wissenschaften / Ingenieurwissenschaften / Ingenieurwissenschaften und zugeordnete Tätigkeiten
Freie Schlagwörter:Absolute fluorometry; Deactivation pathways; Fluorescence; IR; Integrating sphere spectroscopy; NIR; Nanoparticle; Photophysics; Quantum yield; Surface chemistry; Upconversion
Veranstaltung:15th Conference on Methods and Applications in Fluorescence
Veranstaltungsort:Bruges, Belgium
Beginndatum der Veranstaltung:10.09.2017
Enddatum der Veranstaltung:13.09.2017
Verfügbarkeit des Dokuments:Datei im Netzwerk der BAM verfügbar ("Closed Access")
Datum der Freischaltung:29.11.2017
Referierte Publikation:Nein
Eingeladener Vortrag:Nein
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