A1 Refereed original research article in a scientific journal
y Environmental Impact on the Excitation Path of the Red Upconversion Emission of Nanocrystalline NaYF4:Yb3+,Er3+
Authors: Hyppanen I, Hoysniemi N, Arppe R, Schaferling M, Soukka T
Publisher: AMER CHEMICAL SOC
Publication year: 2017
Journal: Journal of Physical Chemistry B
Journal name in source: JOURNAL OF PHYSICAL CHEMISTRY C
Journal acronym: J PHYS CHEM C
Volume: 121
Issue: 12
First page : 6924
Last page: 6929
Number of pages: 6
ISSN: 1932-7447
DOI: https://doi.org/10.1021/acs.jpcc.7b01019
Abstract
The mechanism for red upconversion luminescence of Yb-Er codoped materials is not generally agreed on in the literature. Both two-photon and three-photon processes have been suggested as the main path for red upconversion emission. We have studied beta-NaYF4:Yb-3,Er3+ nanoparticles in H2O and D2O, and we propose that the nanoparticle environment is a major factor in the selection of the preferred red upconversion excitation pathway. In H2O, efficient multiphonon relaxation (MPR) promotes the two-photon mechanism through green emitting states, while, in D2O, MPR is less effective and the three-photon path involving back energy transfer to Yb3+ is the dominant mechanism. For the green upconversion emission, our results suggest the common two-photon path through the F-4(9/2) energy state in both H2O and D2O.
The mechanism for red upconversion luminescence of Yb-Er codoped materials is not generally agreed on in the literature. Both two-photon and three-photon processes have been suggested as the main path for red upconversion emission. We have studied beta-NaYF4:Yb-3,Er3+ nanoparticles in H2O and D2O, and we propose that the nanoparticle environment is a major factor in the selection of the preferred red upconversion excitation pathway. In H2O, efficient multiphonon relaxation (MPR) promotes the two-photon mechanism through green emitting states, while, in D2O, MPR is less effective and the three-photon path involving back energy transfer to Yb3+ is the dominant mechanism. For the green upconversion emission, our results suggest the common two-photon path through the F-4(9/2) energy state in both H2O and D2O.
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