The optical properties of five different nanocrystalline Y(2)O(3):Er(3+), Yb(3+) samples are presented and discussed. Green and red emission was observed following excitation with 488 nm and attributed to (2)H(11/2), (4)S(3/2)-->(4)I(15/2), and (4)F(9/2)-->(4)I(15/2) transitions, respectively. Striking red enhancement was observed in the upconversion spectra when exciting the Y(2)O(3):Er(3+), Yb(3+) samples with 978 nm, and it became more pronounced with an increase in Yb(3+) concentration. A cross relaxation mechanism ((4)F(7/2)-->(4)F(9/2) and (4)F(9/2)<--(4)I(11/2)) was responsible for directly populating the (4)F(9/2) state but did not explain the difference in the magnitude of red enhancement between identically doped bulk and nanocrystalline Y(2)O(3):Er(3+), Yb(3+) samples. The (4)F(9/2) level was populated via a nonresonant mechanism that involved the (4)F(9/2)<--(4)I(13/2) transition that is more prevalent in the nanocrystals, which is due to the high energy phonons inherent in this type of material. In nanocrystalline Y(2)O(3):Er(3+), Yb(3+), we observe a change in the upconversion mechanism responsible for populating the (4)S(3/2) state, from a two-photon to a three-photon process with an increase in Yb(3+) concentration. An explanation to account for this behavior is presented. (C) 2004 American Institute of Physics.

Significance of Yb3+ concentration on the upconversion mechanisms in codoped Y2O3:Er3+, Yb3+ nanocrystals

SPEGHINI, Adolfo;BETTINELLI, Marco Giovanni
2004-01-01

Abstract

The optical properties of five different nanocrystalline Y(2)O(3):Er(3+), Yb(3+) samples are presented and discussed. Green and red emission was observed following excitation with 488 nm and attributed to (2)H(11/2), (4)S(3/2)-->(4)I(15/2), and (4)F(9/2)-->(4)I(15/2) transitions, respectively. Striking red enhancement was observed in the upconversion spectra when exciting the Y(2)O(3):Er(3+), Yb(3+) samples with 978 nm, and it became more pronounced with an increase in Yb(3+) concentration. A cross relaxation mechanism ((4)F(7/2)-->(4)F(9/2) and (4)F(9/2)<--(4)I(11/2)) was responsible for directly populating the (4)F(9/2) state but did not explain the difference in the magnitude of red enhancement between identically doped bulk and nanocrystalline Y(2)O(3):Er(3+), Yb(3+) samples. The (4)F(9/2) level was populated via a nonresonant mechanism that involved the (4)F(9/2)<--(4)I(13/2) transition that is more prevalent in the nanocrystals, which is due to the high energy phonons inherent in this type of material. In nanocrystalline Y(2)O(3):Er(3+), Yb(3+), we observe a change in the upconversion mechanism responsible for populating the (4)S(3/2) state, from a two-photon to a three-photon process with an increase in Yb(3+) concentration. An explanation to account for this behavior is presented. (C) 2004 American Institute of Physics.
2004
INFRARED QUANTUM COUNTERS; LANTHANIDE-DOPED Y2O3; EMISSION
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11562/305028
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