Site selective spectroscopy of surfactant-assembled Y₂O₃:Eu nanotubes

Y₂O₃:Eu nanotubes were synthesized by a surfactant assembly mechanism. Under ultraviolet-light excitation, the nanotubes present luminescence properties different from that of Y₂O₃:Eu nanoparticles. The peak position of the charge transfer band in excitation spectra varies with the monitoring emission peaks, while the emission spectra are dependent on the excitation wavelength. Laser selective spectroscopy was performed to distinguish the local symmetries of the Eu³⁺ ions in the nanotubes. The results of laser-selective excitation indicate that the emission centers near the surface of nanotube walls exhibit inhomogeneously broadened spectra without spectral structures while the two sites (site B and site C) inside the nanotube walls present resolved spectral structures. It is concluded by the number and peak positions of the spectral lines that the sites B and C possess different site symmetries.