The thesis describes found peculiarities of structure of atomic clusters of inorganic semiconductor materials, establishes connections between the structure of the clusters and structure of macroparticles of the corresponding materials, and reports methods of production and studies of properties of the nanocomposite materials important for modern nanophysics and nanoengineering.
Zinc peroxide has been suggested and used as a precursor for the production of zinc oxide clusters. The mass spectra of clusters (ZnO)n have been measured, in which the clusters of enhanced stability, so called "magic" clusters, (ZnO)n have been found at n = 34, 60, 78, 168. The increase in the efficiency of the formation of the "magic" clusters of ZnO and CdSe was found catalyzed by alkylamines. A series of nested shells of (ZnO)n, n = 12m2, m = 1, 2, 3, ... is proposed. It describes the "magic" clusters at n = 60, 168 with "atomic accuracy", and predicts the composition and structure of the next "magic" clusters in the series at n = 360, 660 and larger, which are still undiscovered. The shells are classified in the notations of Goldberg and Conway. Quantum-chemical calculations revealed the symmetry reduction of the nested-shell clusters of ZnO, which is explained by the Jahn-Teller effect. A model of ZnO tetrapod nucleation has been elaborated.
Iodine has been used as a terminator of "broken" bonds in Si and Ge clusters. The series of clusters of SinIm and GenIm of different structures (chains, rings, cages) have been identified in the mass spectra of the products of laser ablation of SiI4 and GeI4 powders. Quantum-chemical calculations revealed the structures of the most stable isomers of the clusters. Their IR and Raman spectra have been calculated. Subnanometer sized Ge clusters of cF8 crystalline structure (diamond structure) have been found in the amorphous silicon-germanium-manganese alloy films.
New method for the synthesis of stable aqueous colloids of (CdSe)33,34 "magic" clusters has been developed, and the role of functional groups of cysteine surfactant has been investigated. CdSe nanoplatelets of atomically precise thickness have been revealed in the cadmium octanoate matrix and characterized by optical absorption and photoluminescent spectroscopic methods, including time-resolved ones.
Several practical applications of nanostructures are suggested. Porous silicon is used as a reducing agent for production of Ag, Au, Pt nanoparticles. The advantage of the method is the chemical purity of the resulting colloids. Porous silica exhibits a similar reductive activity: Ag nanoparticles of 1 nm and 10 nm in diameters are grown in pores of 3.5 nm and 13 nm diameters, respectively. Translucent conductive porous nanocomposite SnO2@SiO2, promising for applications in photoelectrochemical and photovoltaic devices, has been prepared by chemical vapor deposition method.
The effect of photothermal sorption of gases in nanoporous glass (3.5 nm pore diameter) has been revealed. It manifests itself in the dynamic change of gas permeability through the membrane, when the membrane temperature is controled by optical irradiation. The effect is caused by the change of the dominant diffusion mechanism (surface or bulk) of the gas with the variation of the temperature.
The effect of the local field enhancement by plasmonic nanoparticles has been employed for optical recording in copper nanoparticles-silica nanocomposite, using second harmonic of the femtosecond Ti:Sa laser radiation for recording. The fundamental wavelength was used for erasing.
Concentrated colloids of Au@SiO2 nanoparticles have been developed for application as a contrast agent for X-ray studies of living organisms.
