Dispersion and Optical Absorption of Au and Ag Particles Supported on an Amorphous SiO2 Substrate

Abstract Optical absorption spectra were measured on samples of Au and Ag supported on amorphous SiO 2 substrates that had a great variation in the state of metal dispersion. The degree of metal dispersion was evaluated with a packing factor determined by transmission electron microscopy. It was found that the spectral peak wavelength (λ p ) red-shifts with an increase of the packing factor ( q ) for either Au or Ag. The observed λ p - q ) relation was shown to be well simulated with a simple model based on the Maxwell Garnett theory.