Lanthanides upconversion

Controllable synthesis of lanthanide upconversion nanomaterials through impurity doping... 

Chen et al., in Chapter 8, Controllable synthesis of lanthanide upconversion nanomaterials through impurity doping, describe the recent progress in doping-induced control of phase structures, sizes, shapes, as weU as luminescence properties of upconversion (UC) nanomatetials. 

Of course, advances are expected, merging important properties, for example, the utilization of NIR dyes in the harvesting of the solar energy aiming the enhancement of the efficiency of solar cells. Lanthanides upconversion is efficient and visible to the naked eye, provided that powerful excitation sources are used. Infrared light from the sun can hardly lead to observation of visible photons via upconversion. The efficiency of the process is indeed very low [130]. 

Liu, Q Feng, W and Li, F. (2014) Water-soluble lanthanide upconversion nanophosphores synthesis and bioimaging in vivo. Coord. Chem. Rev., 273-274, 100-110. 

Lanthanide (Ln) - or rare-earth-doped upconverting nanocrystals usually have similar optical properties as their bulk counterparts [45]. Upconversion is characterized by the successive absorption of two or more photons via intermediate... 

Following the introduction to size-dependent nanophenomena presented in the previous sections, we now focus our attention on the luminescence properties of lanthanide ions at additional sites or distorted structure existing in nanophases. Phenomena of prolonged luminescence lifetime, anomalous thermalization, upconversion luminescence, dynamics of long-range interaction with two-level-systems (TLS), and quantum efficiency are to be discussed. 

Upconversion lanthanide-containing nanophosphors, which emit higher-energy photons when excited by lower-energy photons have stirred increasing research interest in recent years. The predominant mechanisms of upconversion in nanophosphors are excited-state absorption (ESA), energy-transfer upconversion (ETU) and photon avalanche (PA) (Prasad, 2004 Auzel, 2005). In the ESA process, two photons are sequentially absorbed by the same ion,... 

Weng, D., Zheng, X., and Jin, L. (2006) Assembly and upconversion properties of lanthanide coord polymers based on hexanuclear building blocks with p,3-OH bridges. European Journal of Inorganic Chemistry, 20, 4184 190. 

Figure 13.36 Upconversion luminescence spectrum of the Y Er-Yb co-doped coordination polymer [(Y Er-Yb)(oba)(ox)o.5(H20)2]n [113]. (Reproduced from Inorganica Chimica Acta, 362, C. Y. Sun et al., Assembly and upconversion luminescence of lanthanide-organic frameworks with mixed acid hgands, 325-330, 2009, with permission from Elsevier.)...

Wang, R and Liu, X.G. (2009) Recent advances in the chemistry of lanthanide-doped upconversion nanocrystals. 

Weng, D.R, Zheng, X.J., Chen, X.B., etal. (2007) Synthesis, upconversion luminescence and magnetic properties of new lanthanide-organic frameworks with (4 )2(4, 6, 8 ) topology. European Journal of Inorganic... 

Heer, S., Kompe, K., Gudel, H.U., and Haase, M. (2004) Highly efficient multicolour upconversion emission in transparent colloids of lanthanide-doped NaYp4 nanocrystals. Advanced Materials, 16, 2102-2105. 

Chatteriee, D.K., Rufalhah, A.J., and Zhang, Y. (2008) Upconversion fluorescence imaging of cells and small animals using lanthanide doped nanocrystals. Biomaterials, 29, 937—943. 

Wang, F. and Liu, X.G (2008) Upconversion multicolor fine-tuning visible to near-infrared emission from lanthanide-doped NaYF4 nanoparticles. Journal of the American Chemical Society, 130, 5642-5643. 

Table 2. Transition metal ions in doped halide lattices for which upconversion luminescence has been demonstrated, including relevant mechanistic and electronic-structural information. The lightest and heaviest lanthanides showing single-ion upconversion are also listed. Adapted from [17] ...

The concept of upconversion 32) in which higher-lying states of an activator are excited by successive energy transfers from a less energetic sensitizer has also been applied to lanthanide lasers (33). 

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