Kraft, Marco and Wuerth, Christian and Muhr, Verena and Hirsch, Thomas and Resch-Genger, Ute (2018) Particle-size-dependent upconversion luminescence of NaYF4: Yb, Er nanoparticles in organic solvents and water at different excitation power densities. NANO RESEARCH, 11 (12). pp. 6360-6374. ISSN 1998-0124, 1998-0000
Full text not available from this repository. (Request a copy)Abstract
A systematic study of the luminescence properties of monodisperse beta-NaYF4: 20% Yb3+, 2% Er3+ upconversion nanoparticles (UCNPs) with sizes ranging from 12-43 nm is presented utilizing steady-state and time-resolved fluorometry. Special emphasis was dedicated to the absolute quantification of size- and environment-induced quenching of upconversion luminescence (UCL) by high-energy 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 F-4(9/2) 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 F-4(9/2) energy level of Er3+, which correlate with the size-, environment-, and P-dependent quenching states of the higher Er3+ energy levels.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | QUANTUM YIELDS; UPCONVERTING NANOPARTICLES; IN-VITRO; NANOCRYSTALS; PERSPECTIVES; EMISSION; SURFACE; CORE; NANOPHOSPHORS; ENHANCEMENT; upconversion; nanoparticle; quenching; diameter; water; cyclohexane |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Analytische Chemie, Chemo- und Biosensorik > Bioanalytik und Biosensorik (Prof. Joachim Wegener) |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 04 Oct 2019 08:38 |
| Last Modified: | 04 Oct 2019 08:38 |
| URI: | https://pred.uni-regensburg.de/id/eprint/13406 |
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