RESUMO
A novel hybrid nanostructure, that is a Ag nanoparticle decorated LaF(3):Yb(3+)/Ln(3+)@SiO(2) nanosphere (Ln=Er, Tm), was constructed by a facile strategy, and characterized by XRD, TEM, FTIR, XPS and UV-vis-NIR absorption. Obvious spectral broadening and red-shift on the surface plasmon resonance were obtained by adjusting the size and configuration of Ag nanoparticles. Effective upconversion luminescence enhancements for Er(3+) and Tm(3+) containing samples were obtained. It is suggested that the luminescence enhancement results from both the excitation and emission processes, and the configuration of the studied hybrid nanostructure is an efficient system to enhance the luminescence emission of rare earth doped nanomaterials. It is believed that the enhancement from the hybrid nanostructure will find great potential in the development of photovoltaic solar cells.
Assuntos
Nanopartículas Metálicas/química , Nanotecnologia/métodos , Prata/química , Diagnóstico por Imagem , Érbio/química , Análise de Elementos Finitos , Lantânio/química , Luminescência , Microscopia Eletrônica de Transmissão , Espectroscopia Fotoeletrônica , Silanos/química , Dióxido de Silício/química , Energia Solar , Espectrofotometria Ultravioleta , Espectroscopia de Infravermelho com Transformada de Fourier , Espectroscopia de Luz Próxima ao Infravermelho , Ressonância de Plasmônio de Superfície , Túlio/química , Difração de Raios XRESUMO
NaYF4:Yb3+, Er3+, Mn2+ nanocrystals with cubic crystal phase were obtained by a facile solvothermal method through doping a proper amount of Mn2+ ions to the nanocrystals. The results of XRD and TEM showed that the as-prepared samples were well crystallized and their average size was about 25 nm. Under excitations at 978.5 nm and at 532 nm, obvious enhancement and regulation of upconversion and downconversion fluorescence were obtained. Upconversion emission spectra indicate that these effects were independent of doped concentrations of Er3+ and Yb3+, excitation power, and the excitation wavelength in the current study. It is concluded that the enhancement of fluorescence emissions is mainly due to the change of local symmetry around Er3+ ions, while the regulation of red-to-green ratios was caused by efficient energy transfer between Er3+ and Mn2+ ions. This kind of upconversion material has a great potential in bioimaging and drug delivery since the excitation and emission falls into the region of "optical window" of biological tissues.