Infrared-to-ultraviolet up-conversion luminescence of YF3:Yb3+, Tm3+ microsheets

Controlled synthesis and luminescence properties from cubic to hexagonal NaYF4:Ln3+ (Ln=Eu and Yb/Tm) microcrystals

“…The pump light excites only the Yb 3+ ions, and three successive energy transfers from Yb 3+ to Tm 3+ populate 3 H 5 , 3 F 2 , and 1 G 4 levels. The 1 D 2 level of Tm 3+ cannot be populated by the fourth photon from Yb 3+ via energy transfer to the 1 G 4 due to the large energy mismatch (about 3500 cm −1 ) between them [1]. The cross-relaxation process of 3 F 2 + 3 H 4 → 3 H 6 + 1 D 2 [21] as well as 1 G 4 + 3 H 4 → 3 F 4 + 1 D 2 [22] between Tm 3+ ions play an important role in populating 1 D 2 level.…”

“…Fluorides are efficient hosts for down-conversion (DC) and upconversion (UC) luminescence of rare earth (RE) ions due to their low phonon energies and optical transparency over a wide wavelength range [1]. Many applications of RE-doped fluorides have been demonstrated, such as lasers [2], optical communications [3], display devices [4], and so on [5].…”

Energy transfer efficiency in YF3 nanocrystals: Quantifying the Yb3+ to Tm3+ infrared dynamics

“…As it can be seen, 16,[29][30][31] As it can be deduced from Figure 2(c), the probability of the second and third upconversion processes depends on the probability of the first IR energy transfer from Yb 3þ ions to Tm 3þ ions, which triggers all the subsequent steps. Therefore, the first energy transfer mechanism is the key process to allow the upconversion, and any change in that process will strongly affect the intensity of the visible and UV emissions.…”

Spectroscopic properties Eu3+ doped and Tm3+/Yb3+ codoped oxyfluoride glass ceramics containing Ba2GdF7 nanocrystals

“…Because the 1 D 2 level of Tm 3+ cannot be populated by absorption a photon from Yb 3+ via energy transfer to the 1 G 4 due to the large energy mismatch (about 3500 cm À1 ) between them, the energy transfer upconversion process for the 3 F 2 þ 3 H 4 ! 3 H 6 þ 1 D 2 between Tm 3+ ions may alternatively play an important role in populating 1 D 2 level [21][22][23] from which the UV band at 359 nm arise. After the 1 D 2 level was populated, the 3 P 2 level can be excited by another energy transfer process from Yb 3+ to Tm 3+ .…”