Formation of J-aggregates of Thiamonomethincyanine Dyes in the Presence of CdTe Nanoparticles

The conditions of formation of J-aggregates for three types of thiamonomethincyanine dyes, whose structure is differed by end groups, are studied depending on their concentration and type of interaction with CdTe nanoparticles with size of about 3 nm in aqueous dispersions. The influence of dye structure on the efficiency of formation of J-aggregates in solutions and in films was found. It was found that quantum dots (QDs) of CdTe stabilized by thioglycolic acid can adsorb J-aggregates of the dye molecules on their surface. It was shown for the first time that the hybrid structure of dye-CdTe can be formed through the interaction of negatively charged dye molecules and negatively charged surface of the QDs through the formation of neutral aggregates. It was not found any processes of energy transfer from dye to the particles of CdTe neither for the dimer - CdTe system nor for the J-aggregates – CdTe system. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3544

Optical alignment and orientation of excitons in ensemble of core/shell CdSe/CdS colloidal nanoplatelets

We report on the experimental and theoretical studies of optical alignment and optical orientation effects in an ensemble of core/shell CdSe/CdS colloidal nanoplatelets. The dependences of three Stokes parameters on the magnetic field applied in the Faraday geometry are measured under continuous wave resonant excitation of the exciton photoluminescence. Theoretical model is developed to take into account both bright and dark exciton states in the case of strong electron and hole exchange interaction and random in-plane orientation of the nanoplatelets in ensemble. The data analysis allows us to estimate the time and energy parameters of the bright and dark excitons. The optical alignment effect enables identification of the exciton and trion contributions to the photoluminescence spectrum even in the absence of a clear spectral line resolution.Comment: main paper (17 pages) and SI (6 pages

Molecular dynamics study of the acoustic emission during nanoindentation of iron crystal

In the paper simulation of the indentation of iron crystal was carried out using the method of molecular dynamics. We investigated the effect of vibrations on the AE under the impact of a single element (indenter) with a certain amount of material. Fluctuations of the forces acting on the sensor, changing of the system energy and the formation of defects during loading were analyzed. The force signal showed the increase in its amplitude and power spectrum as well as the median frequency drop under loading by vibrating indenter. The rationale behind all these changes may be dependence between the vibration amplitude and full system energy