Photoluminescence from surfactant-assembled Y2O3:Eu nanotubes

${\mathrm{Y}}_2{\mathrm{O}}_3:\mathrm{Eu}$ nanotubes were fabricated by a surfactant assembly mechanism. The tubular structure was characterized by transmission electron microscopy. Under an ultraviolet-light excitation, the nanotubes show a relatively intense emission peak at 618 nm besides the 610 nm peak, different from that of single ${\mathrm{Y}}_2{\mathrm{O}}_3:\mathrm{Eu}$ nanocrystallites. The results of laser-selective excitation indicate that the emission centers near the surface of nanotube walls exhibit inhomogenously broadened spectra without spectral structures while the two sites (sites B and C) inside the nanotube walls present legible spectral structures. It is concluded by the number and peak positions of Stark levels that the sites B and C possess different site symmetries.