Low-phonon energy

Apart from Eu3+ and Tb3+, few studies have been reported on optical properties of lanthanide ions doped in ZnS nanociystals. Bol et al. (2002) attempted to incorporate Er3"1" in ZnS nanociystal by ion implantation. They annealed the sample at a temperature up to 800 °C to restore the crystal structure around Er3"1", but no Er3"1" luminescence was observed. Schmidt et al. (1998) employed a new synthesis strategy to incorporate up to 20 at% Er3"1" into ZnS (1.5-2 nm) cluster solutions which were stabilized by (aminopropyl)triethoxysilane (AMEO). Ethanolic AMEO-stabilized Er ZnS clusters in solutions fluoresce 200 times stronger at 1540 nm than that of ethanolic AMEO-Er complexes. This is explained by the very low phonon energies in ZnS QDs, and indicates that Er3+ ions are trapped inside chalcogenide clusters. However the exact position of Er3+ in ZnS clusters remains unknown. Further spectroscopic and structural analyses are required in order to obtain more detailed information. 

Fluoride glasses are hosts of prime interest for rare-earth spectroscopy. They show low phonon energies, which induce high quantum efficiencies of rare-earth... 

Because of the wide transmission range and low phonon energies of fluoride glasses, the observation of numerous rare-earth laser lines is possible at wavelengths beyond 2 fim, where the transmission of silica fibers is extremely poor. Laser sources around 2 /jm are of special interest because they belong, not only to the eye-safe spectral domain, but also to an optical transparency window of the atmosphere. Two fluoride glass fiber lasers have been demonstrated in that region. First, a Ho3+ laser with the 5I7 -> 5I8 transition at 2.024 /on which delivers 250 mW with 60%... 

Also Ni + can give an emission at 300 K, located in the IR. At low temperature, V + (d ) and Co + (d ) show an infrared emission when incorporated in lattices with low phonon energies like halides and chalcogenides. For most ions. 

Recently, we reported that hetero-valance dopants (Ln ions) induced size-control in alkaline-earth fluorides (MF2, M = Ca, Sr, Ba) for the first time (Chen et al., 2010). MF2 is selected as the doping host because of its high solubility for trivalent lanthanide ions and its low phonon energy. It is evidenced that using lanthanide ions to substitute for divalent alkaline-earth ones in MF2 nanocrystals allows the as-obtained products with nonuniform size and shape to be easily modified into monodispersed nanospheres with ultra-small sizes of 5 nm in a solution system (Figure 8.7a and b). The possible mechanism is as follows Each substitution of by Ln " in MF2 requires an extra F for charge... 

The LaOBr host has low phonon energy, which indicates that LaOBrEr " may have high luminescent efficiency [14]. Under excitation into the " In/2 level of Er ions by 980-nm laser, the two- and three-photon upconversion luminescence of... 

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