Chemiluminescence in Ozonolysis of Solutions of Fullerene C60

We have discovered and studied chemiluminescence in ozoneoxidation of the solutions of C₆₀ in toluene, benzene, methylnaphthalene, tetrachloroethane, and CCl₄ and photoluminescence of the products of ozonolysis. Irrespective of the nature of a solvent, the chemiluminescence and photoluminescence are attributed to radiation (_max = 660 nm at maximum brightness of luminescence) of fullerene polyketones O=C₆₀=[O] _m (m = 1–19). The visually observed fluorescence of polyketones is much brighter than the wellknown fluorescence of C₆₀ and of the majority of its derivatives. A hypsochromic shift of the maxima of the chemiluminescence spectra with increase in the time of ozonolysis is discovered, which is associated with decrease in the effect of the system of conjugated C=C bonds of the skeleton of C₆₀ on radiating chromophore C=O^*. Reactions with participation of oxofullerencarbonyloxide, i.e., intermediates of the ozonolysis of fullerene, are presumed as luminous stages of chemiluminescence.     

Nanobionics of Pharmacologically Active Derivatives of Fullerene C60

The physical–chemical mechanisms of pharmacologic functioning of amino acid derivatives of fullerene C₆₀ (ADF) have been studied. ADF were shown to penetrate through the lipid bilayer of liposomes without destruction of membrane integrity. ADF are able to carry bivalent metal ions through phospholipid bilayer owing to the formation of complexes. It was shown that stereoisomers of ADF selectively penetrate into phospholipid membranes. In contrast to D-isomers, L-isomers penetrate through the phosphatidylcholine membrane into liposome interior. Stereo-specific effect of ADF enantiomers was also observed in reaction of peroxidation of lipids. Besides that, ADF bring about a substantial increase in the catalytic activity of monoaminoxidases A and B. The directed intraprotein electron transfer was studied by creating a donor–acceptor pair in a water solution in the presence of ADF. To realize the intraprotein electron transfer, the model system was produced on the base of apomyoglobin by incorporating ADF (electron acceptor) into the heme pocket of protein instead of removed heme. It was established that the fullerene C₆₀ and its derivatives did not produce specific anti-C₆₀ antibodies, both IgG and IgE classes, while ADF themselves are efficient adjuvants, i.e. they increased the antibody response to poor antigens. Some ADF were found to inhibit the human immunodeficiency virus and human cytomegalovirus infection.     

On the Supermolecular Structure of Fullerene C60 Solutions

Small angle X‐ray scattering (SAXS) and wide angle X‐ray scattering (WAXS) techniques were used for investigation of fullerene C₆₀ solutions in toluene and p‐xylene. On all SAXS curves, intensity decreases to some constant value of I_C with increase of scattering angle. The value of I_C depends on concentration non‐monotonically: it first slightly increases, then drops sharply to some minimal value, and then increases again. A qualitative explanation of such dependence is offered. It is supposed that the presence of fullerene C₆₀ in solution suppresses thermal fluctuations of density in the solvent. In combination with the X‐ray data the results obtained for solutions of fullerene C₆₀ by various others techniques (calorimetry, densimetry, etc.) are discussed. Possible models of a supermolecular structure of fullerene C₆₀ solutions in good solvents are considered.     

Novel Nanocomposites of Polypyrrole Doped with Fullerene C60

This paper reports on the structural, thermal, and dielectric properties of polypyrrole/fullerene C₆₀ nanocomposites synthesized by a interfacial polymerization method. Fourier transform infrared (FT-IR) and ultraviolet-visible (UV-vis) analyses clearly indicated the existence of interactions between polypyrrole (PPy) and the fullerene C₆₀ nanoparticles. Thermal analyses indicated that the extrapolated onset degradation temperature (T_deg) of PPy increased with increasing doping level. Scanning electron microscopy (SEM) images showed that the fullerene C₆₀ changed the morphology of PPy. Dielectric analyses showed a temperature dependent dielectric relaxation behavior. The relaxation time of the nanocomposites with high doping levels tended to increase with increasing temperature. This behavior of the polypyrrole/fullerene C₆₀ nanocomposites indicated that they could be used as a high temperature ultrasonic transducer.     

Symmetry of Icosahedron and Optical Properties of Fullerene C60

Optics and Spectroscopy - The fullerene level diagram is analyzed using the molecular orbital theory. The interaction of π electrons due to their hopping between adjacent carbon atoms leads to...     

Surface processing with partially ionized plasmas

Partially ionized plasmas are used extensively to process surfaces in many areas of technology. Surface processing in this discussion includes deposition of thin films, etching of the surface itself, and modification of the existing surface by oxidation, nitriding, or texturing. Unique materials can be synthesized in reactive gas glow discharges. The development and optimization of plasma processes is impeded by both a lack of understanding of the mechanistic details and by the formidable parameter space associated with plasma equipment. The complexity of the reactive gas plasma environment coupled with the large parameter space causes difficulty in process development and optimization, but offers opportunities for discovery and invention. The ability of partially ionized plasmas to generate uniform fluxes over wide areas of energetic ions and/or reactive neutral atoms or radicals can be expected to ensure continued widespread applications for the plasma processing of surfaces     

Plasmon dispersion in dense,partially ionized plasmas

A hydrodynamic analysis is presented of the dispersion and damping of long wavelength plasma oscillations in a partially ionized plasma. It is shown that the ionization equilibrium leads to an additional damping mechanism which manifests itselg in a term proportional to the square of the wavenumber.     

Magnetic field effect on the induction of an electric microfield in potassium vapor partially ionized by a laser pulse

A laser-induced electric microfield in potassium vapor partially ionized by laser radiation and placed in an external magnetic field has been studied experimentally. It was found that the dependence of the electric field rise time on the magnetic field strength had a peak value when the plasma frequency is equal to the Larmor frequency. This finding allows us to measure the photoelectron density in weakly ionized potassium vapor. The results are explained in terms of a simple model that shows how the length of the photoelectron trajectory changes with the magnetic field. Received: 4 February 2002 / Revised version: 20 June 2002 / Published online: 25 September 2002 RID="*" ID="*"Corresponding author. Fax: +374-32/31172, E-mail: rdramp@ipr.sci.am     

部分离化激光等离子体的受激喇曼散射不稳定性

由于部分离化激光等离子体中存在束缚电子，它可显著改变其参量不稳定性。本文分析了部分离化激光等离子体的受激喇曼散射的非线性色散关系，计算了钕玻璃倍频和三倍频激光受激喇曼散射的增长率，结果表明，前向受激喇曼散射显著增强，后向受激喇曼散射影响不大。     

Quantum molecular dynamics of partially ionized plasmas

We study a partially ionized hydrogen plasma by means of quantum molecular dynamics, which is based on wave packets. We introduce a new model which distinguishes between free and bound electrons. The free electrons are modelled as Gaussian wave packets with fixed width. For the bound states the 1s-wave function of the hydrogen atom is assumed. In our simulations we obtain thermodynamic properties in the equilibrium such as the internal energy and the degree of ionization. The degree of ionization is in good agreement with theoretical predictions. The thermodynamic functions agree well with results from quantum statistics for 10000 K ≲ T ≲ 40000 K.     

Multicomponent transport algorithms for partially ionized mixtures

We investigate iterative methods for solving linear systems arising from the kinetic theory of gases and providing multicomponent transport coefficients of partially ionized plasmas. We consider the situations of weak and strong magnetic fields as well as electron temperature nonequilibrium and the linear systems are investigated in their natural constrained singular symmetric form. Stationary iterative techniques are considered with new more singular formulations of the transport linear systems as well as orthogonal residuals algorithms. The new formulations are derived by considering generalized inverses with nullspaces of increasing dimension. Numerical tests are performed with high temperature air and iterative techniques lead to fast and accurate evaluation of the transport coefficients for all ionization levels and magnetic field intensities.     

Rheological Behavior of Poly(vinylpyrrolidone)/Fullerene C60 Complexes in Aqueous Medium

Aqueous solutions of complexes formed between poly(vinylpyrrolidone) (PVP), as a matrix polymer, and fullerene C₆₀ were investigated. The effect of the external hydrodynamic field on the supermolecular assemblies formed by the complexes was analyzed. Despite the low content in the complexes (1.5 mass%), fullerene significantly modified the viscosity of aqueous PVP. Thus, the dynamic viscosity of the PVP/C₆₀ complexes grew faster than that of the pure PVP upon increasing the PVP/C₆₀ concentration. The difference in viscosities is especially pronounced for semidilute solutions. As a possible explanation, it is assumed that fullerenes act as crosslinks, in addition to the physical entanglements of the PVP macromolecules, which appear in the vicinity of the crossover concentration. Shear flow corresponding to the high shear rates destroyed fullerene‐induced intermolecular crosslinks in PVP/C₆₀ solutions.     

Dimer and cluster formation in C60 photoreaction

The process of phototransformation in C₆₀ was analysed by means of Raman spectroscopy for single crystals irradiated at various temperatures between 80 K and 450 K. The activation window for the transformation process was found to be between the temperature of the first order phase transition of 260 K and an upper temperature of about 400 K. Detailed features of the resulting spectra were found to depend on the transformation temperature. From a comparison with ab initio calculations of Porezag et al. the material irradiated at high temperatures could be assigned to a C₆₀ dimer whereas the material phototransformed at room temperature could not be identified with a simple cluster.     

Nuclear Magnetic Resonance Spectra of Polyhydroxylated Fullerene C60(OH)n

Polyhydroxylated fullerene C₆₀(OH)_n (with an estimated number of hydroxyl groups n = 38–44) synthesized from pure fullerene by mixing a benzene solution of C₆₀ with a NaOH aqueous solution in the presence of a catalyst was studied with ¹H and ¹³C solid-state nuclear magnetic resonance. Possible features of the structure of a molecule shell were revealed from ¹H NMR data. The ¹³C spectrum showed a peak splitting with an increase in temperature, which is probably due to fullerenol isomers.

     

强激光部分离化等离子体成丝不稳定性

从部分离化等离子体和通常的全离化等离子体的差异是存在束缚电子出发,分析强激光在部分离化等离子体中的传播和折射指数,其束缚电子加强成丝不稳定性的发展.对钕玻璃三倍频激光金靶等离子体的原子成丝不稳定性进行了计算和分析.结果表明强激光部分离化等离子体的原子成丝不稳定性显著高于相对论成丝不稳定性. 关键词： 激光等离子体相互作用 部分离化等离子体 成丝不稳定性     

电场作用下C60富勒烯二聚体分子的几何构型与失效

采用分子力学与量子力学相结合的方法,模拟了电场作用下C60富勒烯二聚体(2C60)分子的几何构型与失效行为,讨论了三种不同方向外加电场对2C60分子几何变形、构型失效、电荷分布与极化偶极矩的影响,并与电场作用下C60富勒烯分子的几何变形与失效行为进行了对比.研究结果表明,2C60分子的几何变形与失效行为与外加电场的方向密切相关.当外加电场与2C60分子的桥接C-C键平行时,2C60分子很容易发生失效,且失效形式也十分独特.