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Tunneling electron transport through CdS nanocrystal arrays fabricated by the Langmuir-Blodgett method are studied by scanning electron spectroscopy. The effect of the matrix-annealing atmosphere on tunneling transport through the nanocrystal arrays is studied. Electron capture at traps in the case of nanocrystals annealed in vacuum is detected by tunneling current-voltage characteristics analyzed using a model relating the data of tunneling spectroscopy, photoluminescence, and quantum-mechanical calculation. Analysis shows that the nanocrystal surface is passivated by an ammonia monolayer upon annealing in an ammonia atmosphere. It is found that the substrate and surrounding non-passivated nanocrystals have an effect on the electron polarization energy.

Forster resonance transfer of excitons from self-assembled InAs/AlAs quantum dots to cyanine dye molecules deposited on the structure surface is investigated. It is shown that the efficiency of the exciton transfer changes upon the interaction of cyanine dye molecules with chloroform due to a change in the molecule dipole moment.

Raman scattering (including nonresonant, resonant, and surface enhanced scattering) of light by optical and surface phonons of ZnO nanocrystals and nanorods has been investigated. It has been found that the nonresonant and resonant Raman scattering spectra of the nanostructures exhibit typical vibrational modes, E 2(high) and A 1(LO), respectively, which are allowed by the selection rules. The deposition of silver nanoclusters on the surface of nanostructures leads either to an abrupt increase in the intensity (by a factor of 103) of Raman scattering of light by surface optical phonons or to the appearance of new surface modes, which indicates the observation of the phenomenon of surface enhanced Raman light scattering. It has been demonstrated that the frequencies of surface optical phonon modes of the studied nanostructures are in good agreement with the theoretical values obtained from calculations performed within the effective dielectric function model.

The optical properties of CdS nanoclusters are studied for samples in which the nanoclusters are embedded in the Langmuir-Blodgett film matrix or the matrix is removed by annealing in vacuum or ammonia atmosphere. After annealing the samples in vacuum or ammonia, the bands of emission from the nanoclusters and from the surface states appear in the photoluminescence spectrum, with the peaks at 2.9 or 2.7 eV and at 1.9 or 2.1 eV, respectively. It is found that, after treating the samples with ammonia, the photoluminescence of the nanoclusters becomes more intense, whereas the photoluminescence corresponding to recombination via the levels of the surface states becomes less intense. It is established that the increase in the photoluminescence intensity for the nanoclusters and the difference between the temperature dependence of the photoluminescence peak position and the temperature dependence of the band gap of bulk CdS are due to passivation of surface states in the nanoclusters. The experimental data are interpreted in the model of recombination of nonequilibrium charge carriers in the CdS nanoclusters, taking into account the exchange of charge carriers between the nanocrystals and trapping centers at their surface and the recombination of charge carriers via the levels of the surface states.

The study of the mineralogical and geochemical features of ores and their textural and structural relationships at the Nikolaevsky base-metal skarn deposit allowed us to establish the succession of mineral assemblages and to ascertain the complex distribution of elements in minerals, ores, and orebodies resulting from nonuniform development of metasomatic zones in the single ore-metasomatic process. The vertical mineralogical and geochemical zoning of the deposit is expressed in the replacement of economic Pb-Zn mineralization at the lower levels of the skarn orebodies with Ag-Pb-Zn mineralization at the upper levels of the major Vostok-1 orebody located at the contact of limestone and felsic volcanics and the block orebodies at the lower level of felsic volcanic rocks. Au-bearing vein Pb-Ag-Sb mineralization occurs in the near-surface zone of the deposit. Three mineralogical types of ores have been identified: sulfide-hedenbergite, quartz-carbonate-sulfide, and sulfide. The zonal distribution of these types within orebodies is combined with variations in mineralogy and in the distribution of major and minor elements. The statistical processing (the Geokhimiya-1 program) of 96 chemical analyses of monomineralic galena and sphalerite samples taken from skarn showed that an intimate Pb ↔ Bi assemblage is characteristic of the lower levels, whereas a Ag Bi assemblage is typical of the upper levels. The elemental assemblages correspond to definite mineral assemblages, determining the mineralogical and geochemical zoning of the deposit.

The 2-(4-hexadecylmethylamino)phenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazolyl-1-oxy-3-oxide radical, which contains a long alkyl chain and a strong donor substituent conjugated with a nitronyl nitroxide group (an acceptor), was synthesized. The behavior of monolayers formed by this radical on a water surface and the conditions of their transfer onto solid substrates by the Langmuir-Blodgett method were examined. UV-VIS and IR spectroscopies, atomic force microscopy, and small-angle X-ray scattering were used to study the optical and structural characteristics of films prepared from the pure radical and its mixtures with behenic acid. It was revealed that radical aggregates are formed both in solutions and Langmuir-Blodgett films.

The photoluminescence of the CdS nanoclusters formed in the matrix of a Langmuir-Blodgett film is studied in the temperature range 5–300 K. At the temperature 5 K, the photoluminescence spectrum of the nanocrystals consists of two bands, with peaks at 2.95 and 2.30 eV. The temperature dependence of the position of the high-energy photoluminescence band differs from the temperature dependence of the band gap of the CdS bulk crystal. The integrated photoluminescence intensity of this band decreases as temperature increases in the range from 5 to 75 K, increases in the range from 150 to 230 K, and decreases above 230 K. The experimental data are interpreted in the context of the model of recombination of nonequilibrium charge carriers in CdS nanoclusters with regard to the charge-carrier transport in locally coupled clusters different in size. In the model, the energy depth of the traps for electrons is estimated at 120 meV; the estimations of the activation energies of nonradiative recombination yield 5 and 100 meV.

Langmuir-Blodgett films are prepared from lead, cadmium, and copper salts of carboxylic acids, namely, 23-tetracosynoic acid HC≡C(CH2)21COOH (with the terminal triple bond) and 2-docosynoic acid CH3(CH2)18C≡CCOOH (with the internal triple bond). The structural transformations in the films during polymerization under exposure to UV radiation are investigated using X-ray reflectomertry. It is found that the X-ray reflectograms of the initial films prepared from salts of both acids exhibit no less than four or five pronounced intense Bragg reflections. This suggests that the initial films have good layer ordering. The bilayer periods for all the films are determined, and the influence of the salt type on the bilayer period is analyzed. It is established that, under exposure to UV radiation, the structural transformations in the films prepared from the salts of 23-tetracosynoic acid occur without substantial disturbances and defects, as can be judged from the absence of significant changes in the location and intensity of the Bragg reflections. An increase in the time of irradiation of the films prepared from the salts of 2-docosynoic acid leads to an increase in the bilayer period. This effect is especially pronounced for the lead and copper salts. However, upon long-term exposure to UV radiation, the salts undergo photolysis, the bilayer period decreases, and the structure of the film begins to break down.

The optical anisotropy of Langmuir-Blodgett films, along with its variation in the course of polymerization under UV radiation, is studied by ellipsometry at a fixed wavelength of 632.8 nm for several angles of incidence of light. Films of the Cd and Pb salts of acetylenic acids with internal and terminal triple bonds—HC≡ C(CH2)21COOH (I) and CH3(CH2)18C≡CCOOH (II)—are studied. The refractive indices and thicknesses of the films are determined on the basis of a model of a biaxial anisotropic film. It is found that the films of the Pb salt of acid II are biaxial, while the films of the Cd salt of acid II and of the Cd and Pb salts of acid I have nearly uniaxial anisotropy. The calculated thicknesses of monolayers coincide with the thicknesses determined from small-angle x-ray scattering. The anisotropy of the films is shown to vary under UV irradiation. After polymerization of the films, the anisotropy in the plane of the layer virtually vanishes, while that in the direction perpendicular to the interface is retained.

The structures with CdS, PbS, and ZnS quantum dots produced using the Langmuir-Blodgett method are investigated by infrared (IR) spectroscopy, Raman scattering, and ultraviolet (UV) spectroscopy. The quantum dot size estimated from the UV spectra and high-resolution transmission electron microscopy (HRTEM) falls in the range 2–6 nm. The longitudinal optical (LO) phonons localized in quantum dots and the surface optical vibration modes are revealed in the IR reflection and Raman scattering spectra of the structures under investigation. The frequencies of the surface optical modes are adequately described with allowance made for the effect of localizing optical phonons in the quantum dots.

Surface enhanced Raman scattering is studied in nanostructures with CdS quantum dots formed using the Langmuir-Blodgett technology. Features due to quantum dot longitudinal optical phonons are observed in the Raman spectra of both free CdS quantum dots and such dots distributed in an organic matrix. The surface enhanced Raman scattering by nanostructures with CdS quantum dots covered by an Ag cluster film is observed experimentally. Applying Ag clusters onto the nanostructure surfaces results in a sharp (40-fold) increase in the intensity of Raman scattering by optical phonons in the quantum dots. It is shown that the dependence of surface enhanced Raman scattering on the excitation energy is resonant with a maximum at the energy corresponding to the maximum absorption coefficient of Ag clusters.