Fine control of the photoluminescence properties of CdSe nanoparticles (NPs) dispersed in CHCl3 is achieved by simple adjustment of the NPs concentration. and the wavelength of photoluminescence emission of CdSe NPs can he tuned within the nanometer accuracy. The mechanism of the process is proposed to be relevant to the modulation of the surface states of NPs by the concentration. This solution-based approach offers ail attractive and complimentary process to the conventional band gap engineering, of semiconductor NPs with fine tunable optical properties. (c) 2006 Elsevier Inc. All rights reserved.