Optical transmittance spectra of insulator nanoparticles in bulk heterocomposites

A theoretical model is presented of the visible, near-infrared, and near-ultraviolet transmittance spectra of arbitrarily-shaped small-sized insulator particles embedded in an insulator in relation to the particle dimensions and the radiation frequency. The model is based on a number of assumptions. In the band gap of the nanoparticles, there are allowed energy bands produced by surface defects. Two-particle states (electron-hole pairs) are only slightly confined, and the size-quantized states of charge carriers are formed in the conduction band; the states depend on the shape and dimensions of the nanoparticles. By the example of Al 2 O 3 nanoparticles introduced into a liquid matrix of a transparent insulator, the results of experimental studies are compared with the theoretical model.