A facile strategy based on the reaction of urea and boric acid is developed for the synthesis of toxicity-free BCNO nanocrystals containing carbon impurities and which exhibit efficient multi-color fluorescence under both single-photon and two-photon excitation.
State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, PR China. xfliu@yahoo.cn
