Surface effects on nanoparticles have been explored by picosecond time-resolved spectroscopy using Ce3+ ions doped in yttrium aluminum garnet (YAG) nano-phosphors (NPS) as a probe. Non-exponential decays have been observed over the entire emission band that could be fitted well with four decay components varying from similar to 150 ps to similar to 70 ns. These components have been assigned to originate from sites different in distance from the surface. Surface quenching effects have been found to be negligible when the luminescence centers are more than 7 nm away from the surface. (c) 2007 Elsevier B.V. All rights reserved.