Surface effect of nano-phosphors studied by time-resolved spectroscopy of Ce3+

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 ∼150 ps 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.