Particle size dependence of the volume plasmon energy in cadmium sulphide quantum dots by electron energy loss spectroscopy

The shift of the volume plasmon energy with particle size in cadmium sulphide nanoparticles was examined by energy filtered transmission electron microscopy. This technique allowed the plasmon energy of individual, well-separated particles to be measured. The measured plasmon energy was found to increase with decreasing particle size, in general agreement with the theoretical approximation for plasmon shifting due to the quantum size effect. The nanoparticle diameters ranged between 1.5 and 3.8 nm and they were prepared by mechanochemical processing techniques and then electrophoretically deposited on the transmission electron microscope specimen grids. (C) 1999 American Institute of Physics. [S0021-8979(99)02903-5].