TABLE OF CONTENTS The scattering and absorption of light by the nanoparticles has a number of special features in comparison with macroscopic solids [199]. Experimentally, these special features are most evident when examining a large number of particles. For example, colloid solutions and granular films may be extensively coloured as a result of the specific optical properties of nanoparticles. A classical object for investigating the optical properties of the dispersed media is gold. Even Faraday paid attention to the similarity of the colour of a colloid solution of gold and a gold film and assumed the dispersion state of the gold film.
In absorption of light by fine-grained metal films the visible part of the spectrum contains absorption peaks which are absent in the spectra of bulk metals (in metals the optical absorption by conduction electrons takes place in a wide wavelength range). For example, the granular films of gold particles with a diameter of 4 nm have a distinctive maximum absorption in a range of ? = 560-500 nm [200,201]. The spectra of absorption of nanoparticles Ag, Cu, Mg, In, Li, Na, K also had maxima in the optical range [4,202].
Another special feature of the granular films is a decrease of their absorption in transition from the visible to infrared part of the spectrum in contrast to continuous metal films in which the absorption of radiation increases with increasing wavelength ? [4,201,203 207].
The size effect of the optical properties are important for the nanoparticles whose size...
