O. P. Dmytrenko

Structure and Vibrational Properties of Multi‐walled Carbon Nanotubes Irradiated with High‐energy Electrons

We performed investigations of the changes occurring in the crystalline structure and Raman spectra of multi‐walled carbon nanotubes during high‐energy electron irradiation (Ee = 1.8 MeV) with absorbed doses between 3.0 and 10.0 MGy. It is shown that the formation of radiation‐induced damage is accompanied by an increase in the interlayer correlations as a consequence of interlayer cross‐linking and local variations in the geometry of the multi‐walled carbon nanotubes. Generation of radiation‐induced defects and difference in the mechanisms of their annealing leads to a drop in the integrated intensity of the Raman G‐ and D‐bands as well as a component splitting of the G‐band. It suggests that new vibrational modes appear with an increase of fluence. These modes result from the reconstruction of the structure and geometry of multi‐walled carbon nanotubes and, hence, their symmetry.

Structure and Photoluminescence of Single‐Emulsion C60 and Cu‐C60 Films

Abstract The phase composition of single‐emulsion C60 and Cu‐C60 films and their photoluminescence were studied and analyzed in detail.

Raman Vibrational Properties of Carbon Nanotubes with the Radiation Defect Formation

Studies of changes in the crystal structure of multi-walled carbon nanotubes (MWNT) during the high-energy electron irradiation (E e = 1.8 MeV) with doses from 3.0 to 10.0 MGy are carried out by means of the analysis of the Raman vibrational spectra. It is shown that defects generated by the electron beam irradiation are accompanied by an increase in the interlayer correlations as a consequence of interlayer links and local variations in the geometry of MWNT. The generation of the structural defects leads to the drop in the integral intensities of the G- and D-bands in the Raman scattering spectrum and to the splitting of the G-band into several components. These results are supported by the manifestation of new vibrational modes with increase in the fluence of irradiation which is an indication of the reconstruction of the structure and geometry of MWNT and, respectively, of their symmetry.

Radiation Technologies of Polymer Composites Properties Modification

It was established that a wide structured photoluminescence band (350–700 nm) occurs in bulk specimens of polytetrafluorethylene and its composites with multi-walled carbon nanotubes as a result of thermal and mechanical impact during preparation. Five distinct components of spectra were identified as a manifestation of –C=O– bonds excitation and energy transfer from those bonds to polyenic π-conjugated chains of different lengths. Usage of carbon nanotubes in composites with different content provides quenching of photoluminescence while preserving the nature of irradiation centers. High-energy electronic irradiation leads to further development and redistribution of photoluminescence components.

Photostimulated Processes in PVK-C60 Nanocomposites

We studied dependence of the photoluminescence spectra of the PVK-C60 nanocomposites synthesized by vacuum evaporation on the fullerene concentration as well as the temperature of the samples. Our experiments show that exposure of the PVK-C60 composites to a 514.5 nm irradiation induces reversible changes leading to heterogeneous concentration-dependent modifications of the photoluminescence spectra.

Phosphorescence of the π‐conjugated Polymers with Complex Forming C60 Fullerenes During Irradiation

The photoluminescence spectra and the optical conductivity of the precipitated films of the pure organic molecular PVK polymers and their nanocomposites containing C60 fullerenes with the concentration from 0,5 to 3wt% were studied. The photoluminescence spectra for the composites containing considerable amount of fullerenes irradiated with the 140 keV copper ions and the dose 4,2.1014 ion/cm2 also were investigated. It is shown that the formation of both the intermolecular complexes causing changes of the spectra of photoluminescence and interband electron transitions in the nanocomposites takes place. The ionic implantation with copper leads to the creation of the metallic centers that influences on the formation of new channels of the radiationless recombination and transport of the photogenerated electron‐hole pairs.

Radiative Recombination of Frenkel Excitons in Solid c60 Under Radiation Damages

The behavior of the emission of the excitons localized at different X-centers at the radiation damages by electron beams with an energy of 1.8 MeV and argon ions in the plasma of glow discharge is studied. The nature of X-centers, which contribute to the emission of excitons near energies of 1.5 and 1.6 eV, is discussed. It is shown that the essential reconstruction of the energy spectrum of excitation is observed with increase in the radiation dose, as a result of the radiation damages of C60 molecules.

Irradiation Effect on the Electron Transport Properties of Single-Walled Carbon Nanotube

The conductivity of the metallic (10,10) single-walled carbon nanotube with simulated different types of local topological radiation defects was calculated and analysed.

Computer Simulation of the Irradiation Effect on the Modification of Carbon Nanostructures

The computer simulation of the influence of ionic low energy irradiation on the carbon nanostructures modification is carried out. The spatial distribution of vacancies and its dependence on the projectile energy and energy of defect formation, and also the deposition energy into the electronic subsystem of target were examined and analyzed in detail.