The mechanisms of formation of the spectra of interband optical absorption in nanosystems containing aluminum oxide quantum dots, placed in the matrix of vacuum oil, are presented. It is shown that the electron transitions in the band of the electron-hole pair states cause absorption in the ultraviolet wavelengths, and cause the experimentally observed significant blurring of the absorption band.
Semiconducting thin films of titanium oxide (TiO2) transparent in the UV-visible region were prepared on mica surface by the liquid-phase deposition method. Their irradiation by laser at 405 nm induced photoluminescence at 1700 nm. It was shown that film refractive index (n) depended on the wavelength.
As a part of the dipole approximation we study the interband optical absorption by nanosystem containing quantum dots (QD) alumina in a dielectric matrix. It is shown that the absorption edge of nanosystem mainly formed by two comparable in intensity electron transitions from low excited size quantized hole states on the ground size quantized electron state.
The recently discovered ultralow-threshold nonlinear refraction of low-intensity laser radiation in dielectric nanostructures has an atypical dependence on radiation intensity. We first carry out quantitative measurements of the dependence of the nonlinear response of liquid dielectric nanostructures on the low-intensity radiation and then devise a theoretical explanation. The theory suggests that the nonlinearity is of photoinduced nature instead of a thermal one and depends directly on the nanoparticles electronic structure and the relationship between permittivities of dielectric matrix and nanoparticles.
It has been found that the formation of a biexciton in a nanoheterostructures (NHS) made up of aluminum oxide quantum dots (QDs) synthesized in a dielectric matrix is of threshold character and can occur in a nanosystem, where the distance D between the surfaces of QD is given by the condition Dc(1)≤D≤Dc(2). We have shown that with such an NHS acting as “exciton molecules” (biexcitons consisting of spatially separated electrons and holes) are the QDs of aluminum oxide with excitons localizing over their surfaces. The position of the biexciton state energy band depends both on the mean radius of the QDs, and the distance between their surfaces, which enables one to purposefully control it by varying these parameters of the nanostructure.
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