I. A. Gorbachev

The depending of Langmuir monolayers of quantum dots and fatty acid mixture properties from their components ration

Langmuir monolayers of quantum dots could be used as a platform for creation of planar fluorescent sensors that widely used in biology during immunochemistry analysis. Interesting feature is a creation of matrix with separated quantum dots one from each other. The process of Langmuir monolayers of quantum dots and fatty acid mixtures with different component ratios formation was studied. The method of compression isotherm was used for Langmuir monolayer formation process characterization, atomic force microscopy was used for transferred films characterization. Volume component ratios of 1:1, 1:2. 2:1, 1:5 and 5:1 of arachidic acid and quantum dots were studied. Was shown that increasing of the arachidic acid concentration in the solution cause to decreasing the maximal monolayer area, changing in monolayers liquid phase extensions and type. Also the monolayer compressibility and compression module are changes and achieves a peak value at components ratio of 1:1. At the indicated component ratio the formed Langmuir monolayer of quantum dots and arachidic acid mixture was transferred on the glass substrate and studied by atomic force microscopy.

Ligands Exchange, Studying the Stability and Optical Properties of CdSe/CdS/ZnS Quantum Dots with Liquid Crystal

Liquid crystal (LC) ligands have the ability to control the dispersion and the homogeneity of quantum dots (QDs) in solution. LC phase transition can be used as a tool to control the assembly of dispersed QDs. Comparing the results before and after the ligands exchange (oleic acid to liquid crystal) highlights some important differences in optical and morphology properties of QDs. We have studied changes in optical properties and a shift in the spectral wavelength band of QDs with LC ligands. Application of LC ligands leads to quenching of the emission and excitation spectra intensity of CdSe/CdS/ZnS QDs. Such hybrid materials have interesting potential for usage in a variety of applications such as photonic materials or (bio) chemical sensors.

Electronic properties of A2B6 quantum dots incorporated into Langmuir–Blodgett films

An experimental and theoretical study is performed for features of the electronic spectrum of CdSe/CdS/ZnS quantum dots incorporated into Langmuir–Blodgett films. Analysis of the investigated samples assesses the state of the first three levels of the electron spectrum for a quantum object. Good qualitative and quantitative agreement is achieved between the experimental results and theoretical estimates. It is shown that the mechanism of the observed field emission current through a quantum dot is described satisfactorily by the Morgulis–Stratton theory under the considered experimental conditions.

The study of the formation of monolayers of quantum dots at different temperatures

The process of formation of Langmuir monolayers of quantum dots at the different subphase temperatures was studied by means of compression isotherm, Brewster angle microscopy and transmission electron microscopy. The increasing of the maximum surface pressure from 32 to 44 mN/m takes place with decreasing the temperature from 34 to 11°C. This is due to a decrease in the rate of dissolution of surfactant molecules in water. The increasing of a filling degree of monolayer by the quantum dots and increasing of it uniformity in thickness takes place in this temperature range. The area of bilayer and multilayer film of quantum dots decreasing and the area of quantum dots monolayer is increasing. This change explained by the difference in the phase condition of oleic acid molecules, which stabilized quantum dots.

The influence of redistribution ions in subphase at the properties Langmuir monolayer: physical and theoretical experiments

The formation of a monolayer and its structure depend on many factors. One of the least studied factors is the influence of the electric field. In this regard, the purpose of this study is to investigate the influence of the direction and magnitude of the electric field on the properties of monolayer, formed on the surface of water. The experiments have revealed: the electric field exerts a significant influence on the formation of monolayers, in particular, during liquid phase formation. The second part of the isotherm (corresponding liquid phase) were significantly stretched. We explain the liquid phase extension by the fact of the charge increasing (and change pH) of the surface region. To confirm this assumption also we made computer modelling of process monolayer formation.

Processes in suspensions of nanocomposite microcapsules exposed to external electric fields

Microcapsules with and without magnetite nanoparticles incorporated in the polyelectrolyte shell were prepared. The effect of external electric field on the nanocomposite polyelectrolyte microcapsules containing magnetite nanoparticles in the shell was studied in this work as a function of the electric field strength. Effect of electric fields on polyelectrolyte microcapsules and the control over integrity of polyelectrolyte microcapsules with and without inorganic nanoparticles by constant electric field has been investigated. Beads effect, aggregation and deformations of nanocomposite microcapsule shell in response to electric field were observed by confocal laser scanning microscopy (CLSM). Thus, a new approach for effect on the nanocomposite microcapsule, including opening microcapsule shell by an electric field, was demonstrated. These results can be used for creation of new systems for drug delivery systems with controllable release by external electric field.