Spectroscopic Distinction of Surface and Volume Ions in Cerium(III)- and Terbium(III)-Containing Core and Core/Shell Nanoparticles

Core and core/shell Tb 3+ -doped CePO 4 and LaPO 4 nanoparticles have been prepared in an organic solvent mixture. The particles were characterized by X-ray diffraction (XRD), UV−vis absorption spectra, luminescence spectra, and lifetimes. It is shown that the luminescence spectra of Ce 3+ and Tb 3+ ions at the particle surface differ from those located in the interior of the nanocrystals. The emission of cerium surface ions is red-shifted compared to the emission of ions in the particle center. Tb 3+ ions at the surface display strongly broadened emission lines, indicating a variety of different surface sites.