Abstract
Pumped with a 980-nm diode laser, violet/ultraviolet upconversion fluorescence was presented in Y0.83Yb0.15Er0.02F3 nanocrystals. Observed emissions at 318 nm and 379 nm were affirmed coming from a four-photon excitation process. In comparison with a bulk sample having the same chemical compositions, the nanocrystals had a markedly enhanced ability of emitting violet/ultraviolet upconversion fluorescence. By employing Tm3+ ions as structural probes in the samples, we found that the enhancement could be attributed to the decrease of Judd-Ofelt parameter Ω2. A model for revealing the four-photon excitation process was proposed based on spectral analysis.
Original language | English |
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Pages (from-to) | 296-299 |
Number of pages | 4 |
Journal | Optical Materials |
Volume | 31 |
Issue number | 2 |
DOIs | |
State | Published - 2008 |
Externally published | Yes |
Keywords
- Judd-Ofelt parameter
- Microwave irradiation
- Nanocrystals
- Upconversion