Erbium upconversion

S3/2— I15/2) of erbium ion have a laige emission section and are easy to achieve upconversion, so erbium ion is a good active ion as upconversion phosphors materials. The energy level transition( l]3/2— I15/2) can emit out 1.5 pm eye-safe laser radiation and the ion is also a well active ion for the eye-safe laser material. Gd203 powder with a cubic structure is a good host material for its excellent photics and thermal properties. It not only can be used as upconversion phosphors material but also can be used to prepare transparent ceramics as a host material. 

Two simple examples will be given in order to illustrate the instrumentation and the primary data treatment. The discussion is focused on the technical problems and the interpretation of the results is left to a minimum. The first example deals with the resonance energy transfer (RET) from europium to an organic fluorophore. The distance between the donor and acceptor is kept constant by an oligonucleotide. RET is a very common technique in the case of lanthanides, and therefore the discussion is somewhat lengthy and detailed. The second example deals with a sample of upconversion phosphor containing yttrium, ytterbium and erbium. 

Besides triplet-triplet annihilation, a further process for achieving upconversion luminescence emission under continuous wave low-energy irradiation is based oti the use of lanthanide ions, most often erbium, holmium, and thulium (III) cations. In particular, a large variety of phosphors based on an inorganic host doped by lanthanide cations have been developed. The abundance of available states in these cations opens a large variety of paths for upconversion. As an example (Scheme 7.6), upconversion nanoparticles codoped with ytterbium and erbium cations exhibit a green emission due to the transitions from Hn/2 and respectively " Sn/2 excited states to the ground state as well as a red emission from the F9/2 state [10]. 

Pasquale F.D., Federighi M. Modeling of nniform and pair-in-duced upconversion mechanisms in high-concentration erbium doped silica waveguides. J. Lightwave Technol. 1995 13 1858-1864... 

T1O2 sol-gel layers, 27 Er-Zr second shell coordinations, 27 ESA. See excited state absorption etching technique, 442 ETU. See energy transfer upconversion Euler s critical stress, 226 europium-activated photonic crystal, 379 europium-doped systems. See also erbium-doped systems aluminum-codoping, 378 electric dipole aspects, 373 FLN spectra, 376 luminescence spectra, 374 magnetic dipole aspects, 373 non-radiative lifetimes, 375 non-radiative transitions, 375 radiative lifetimes, 375 room temperature spectra, 376 silica gels, 376... 

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