Synthesis, novel luminescence properties, and surface-enhanced Raman scattering of Au/Y2O3:Eu(3+) composite nanotubes.

Y(OH)3:Eu(3+) nanotubes were synthesized by a facile hydrothermal method first, and then Au particles were grown on the surface of Y2O3:Eu(3+) nanotubes by combining the vacuum extraction method and the annealing process. The composite nanotubes were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The effects of the Au content on the photoluminescence properties of the Au/Y2O3:Eu(3+) composite nanotubes were investigated in detail. In the excitation spectra of Au/Y2O3:Eu(3+) monitored at 614 nm, the (7)F0→(5)H3 transition from Eu(3+) increased with increasing Au content, while the other sharp lines originating from Eu(3+) f-f electron transitions almost vanished. In the emission spectra, the spectral configurations of Eu(3+) in Au/Y2O3:Eu(3+) composite nanotubes varied with the excitation wavelengths. When the excitation wavelength was 256 nm, the (5)D4→(7)F0, (5)D7→(7)F0, (5)G2→(7)F0, (5)L6→(7)F0, (5)D0→(7)F0, (5)D0→(7)F1, (5)D0→(7)F2, (5)D0→(7)F3, and (5)D0→(7)F4 transitions from Eu(3+) ions in Au/Y2O3:Eu(3+) were observed. When the excitation wavelength was 378 nm, the plasmon resonance peak from Au nanoparticles was observed. In addition, 4-ATP was chosen as the model molecule to examine the performance of the Au/Y2O3:Eu(3+) composite nanotubes as SERS substrates. The relative intensities of the SERS spectra enhanced with the increase of Au(+) : Ln(3+) ratio.