Abstract: Au particle of the size in the range of 10—189 nm has been prepared by sodium citrate procedure. The resonance scattering spectra of Au particle have been studied. The nanoparticle solutions of the size in the range of 10—95 nm exhibit red in colour. Their maxmum absorption wavelenth are in the range of 517.8—533.3 nm. The absorption peak shifts to the red with the size increasing. The maxmum resonance scattering peak is at 580 nm. The cube root of the intensity at 580 nm is proportional to the size of Au particles.

Key words: Au particle, Size of particle, Resonance scattering spectroscopy