<?xml version="1.0" encoding="utf-8"?>
<export-example>
  <doc>
    <id>50307</id>
    <completedYear/>
    <publishedYear>2018</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>6360</pageFirst>
    <pageLast>6374</pageLast>
    <pageNumber/>
    <edition/>
    <issue/>
    <volume>11/12</volume>
    <type>article</type>
    <publisherName>Springer Nature</publisherName>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>1</belongsToBibliography>
    <completedDate>--</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Explaining the influence of dopant concentration and excitation power density on the luminescence and brightness of beta-NaYF_4:Yb~(3+),Er~(3+) nanoparticles: Measurements and simulations</title>
    <abstract language="eng">A systematic study of the luminescence properties of monodisperse β-NaYF4: 20% Yb3+, 2% Er3+ upconversion nanoparticles (UCNPs) with sizes ranging from 12–43 nm is presented utilizing steady-state and time-resolved fluorometry.&#13;
Special emphasis was dedicated to the absolute quantification of size- and environment-induced quenching of upconversion luminescence (UCL) by highenergy O–H and C–H vibrations from solvent and ligand molecules at different excitation power densities (P). In this context, the still-debated Population pathways of the 4F9/2 energy level of Er3+ were examined. Our results highlight the potential of particle size and P value for color tuning based on the pronounced near-infrared emission of 12 nm UCNPs, which outweighs the red Er3+ emission under “strongly quenched” conditions and accounts for over 50% of total UCL in water. Because current rate equation models do not include such emissions, the suitability of these models for accurately simulating all (de)population pathways of small UCNPs must be critically assessed. Furthermore, we postulate population pathways for the 4F9/2 energy level of Er3+, which correlate with the size-, environment-, and P-dependent quenching states of the higher Er3+ energy levels.</abstract>
    <parentTitle language="eng">Nano Research 2018</parentTitle>
    <identifier type="doi">10.1007/s12274-018-2159-9</identifier>
    <enrichment key="date_peer_review">03.02.2020</enrichment>
    <enrichment key="opus.doi.autoCreate">false</enrichment>
    <enrichment key="opus.urn.autoCreate">true</enrichment>
    <author>Marco Kraft</author>
    <author>Christian Würth</author>
    <author>V. Muhr</author>
    <author>T. Hirsch</author>
    <author>Ute Resch-Genger</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Nanoparticle</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Nanosensor</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Fluorescence</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Upconversion</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Upconversion nanoparticle</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>NIR</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Photophysics</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Lanthanide</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Size</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Surface chemistry</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Quantum yield</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Mechanism</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Lifetime</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Decay kinetics</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Quenching</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Diameter</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Cyclohexane</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Water</value>
    </subject>
    <collection role="ddc" number="543">Analytische Chemie</collection>
    <collection role="literaturgattung" number="">Verlagsliteratur</collection>
    <collection role="fulltextaccess" number="">Datei im Netzwerk der BAM verfügbar ("Closed Access")</collection>
  </doc>
  <doc>
    <id>40092</id>
    <completedYear/>
    <publishedYear>2017</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>4868</pageFirst>
    <pageLast>4874</pageLast>
    <pageNumber/>
    <edition/>
    <issue>9</issue>
    <volume>89</volume>
    <type>article</type>
    <publisherName>ACS</publisherName>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>1</belongsToBibliography>
    <completedDate>--</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Particle-size-dependent Förster resonance energy transfer from upconversion nanoparticles to organic dyes</title>
    <abstract language="eng">Upconversion nanoparticles (UCNPs) are attractive candidates for energy transfer-based analytical applications. In contrast to classical donor−acceptor pairs, these particles contain many emitting lanthanide ions together with numerous acceptor dye molecules at different distances to each other, strongly depending on the particle diameter.&#13;
UCNPs with precisely controlled sizes between 10 and 43 nm were prepared and functionalized with rose bengal and sulforhodamine B by a ligand-exchange procedure. Timeresolved studies of the upconversion luminescence of the UCNP donor revealed a considerable shortening of the donor lifetime as a clear hint for Förster resonance energy transfer (FRET). FRET was most pronounced for 21 nm-sized UCNPs, yielding a FRET efficiency of 60%. At larger surface-to-volume ratios, the FRET efficiency decreased by an increasing competition of nonradiative surface deactivation. Such dye-UCNP architectures can also provide an elegant way to shift the UCNP emission color, since the fluorescence intensity of the organic dyes excited by FRET was comparable to that of the upconversion emission of smaller particles.</abstract>
    <parentTitle language="eng">Analytical Chemistry</parentTitle>
    <identifier type="doi">10.1021/acs.analchem.6b04662</identifier>
    <identifier type="issn">0003-2700</identifier>
    <identifier type="issn">1520-6882</identifier>
    <enrichment key="date_peer_review">29.05.2017</enrichment>
    <author>V. Muhr</author>
    <author>Christian Würth</author>
    <author>Marco Kraft</author>
    <author>M. Buchner</author>
    <author>A. J. Baeumner</author>
    <author>Ute Resch-Genger</author>
    <author>T. Hirsch</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Upconversion</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>FRET</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Organic dyes</value>
    </subject>
    <collection role="ddc" number="543">Analytische Chemie</collection>
    <collection role="literaturgattung" number="">Verlagsliteratur</collection>
    <collection role="fulltextaccess" number="">Datei im Netzwerk der BAM verfügbar ("Closed Access")</collection>
  </doc>
</export-example>
