Wuerth, C. and Kaiser, M. and Wilhelm, S. and Grauel, B. and Hirsch, T. and Resch-Genger, U. (2017) Excitation power dependent population pathways and absolute quantum yields of upconversion nanoparticles in different solvents. NANOSCALE, 9 (12). pp. 4283-4294. ISSN 2040-3364, 2040-3372
Full text not available from this repository. (Request a copy)Abstract
The rational design of brighter upconversion nanoparticles (UCNPs) requires a better understanding of the radiationless deactivation pathways in these materials. Here, we demonstrate the potential of excitation power density (P)-dependent studies of upconversion (UC) luminescence intensities, slope factors, and absolute quantum yields (Phi(UC)) of popular beta-NaYF4: 20% Yb3+, 2% Er3+ UCNPs of different surface chemistries in organic solvents, D2O, and water as a tool to gain deeper insight into the UC mechanism including population and deactivation pathways particularly of the red emission. Our measurements, covering a P regime of three orders of magnitude, reveal a strong difference of the P-dependence of the ratio of the green and red luminescence bands (I-g/(r)) in water and organic solvents and P-dependent population pathways of the different emissive energy levels of Er3+. In summary, we provide experimental evidence for three photon processes in UCNPs, particularly for the red emission. Moreover, we demonstrate changes in the excited population dynamics via bi- and triphotonic processes dependent on the environment, surface chemistry, and P, and validate our findings theoretically.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | LANTHANIDE-DOPED NANOPARTICLES; UPCONVERTING NANOPARTICLES; LUMINESCENCE; NANOCRYSTALS; NAYF4YB3+,ER3+; MECHANISM; WATER; IONS; NANOPHOSPHORS; SUSPENSIONS; |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Analytische Chemie, Chemo- und Biosensorik |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 14 Dec 2018 13:00 |
| Last Modified: | 25 Feb 2019 12:15 |
| URI: | https://pred.uni-regensburg.de/id/eprint/199 |
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