Thin ferromagnetic nanodisk in transverse magnetic field

The magnetization of a ferromagnetic nanodisk is studied using micromagnetic modeling. It is demonstrated that, under an external magnetic field applied perpendicular to the disk surface, magnetic phase transitions can occur between uniform states, between uniform and vortex states, and between vortex states with different directions of polarization. A simple variation model is proposed describing the observed magnetic states quantitatively.     

“Chemical portrait” of fullerene molecules

Chemical activity of fullerene molecules is associated with a partially radical character of these molecules caused by the presence of effectively unpaired electrons (EUE). Values of the total number of N _D and partial distribution N _DA of EUE over the atoms in a singlet state of molecules C₆₀ and C₇₀ have been calculated. “Chemical portraits” of molecules are presented, and N _DA values are proposed to be used as indicators for chemical activity of atoms and to predict thereby the position of favorable atom-atom contacts in addition reactions with participation of these molecules. Bases of “computational synthesis” procedures for fullerene C₆₀ derivatives are exemplified by initial phases of its fluorination.     

Enhanced Raman scattering provided by fullerene nanoclusters

Two new nonlinear optic effects are observed in crystalline solutions of fullerenes in toluene and carbon tetrachloride. Both are provided by a self-clustering of the solute molecules and are referred to fullerene-enhanced Raman scattering and solvent-enhanced luminescence. The effects are induced by the excitation of charge-transfer states of the fullerene nanoclusters, which makes the latter act as amplifiers of local electric fields. The text was submitted by the authors in English.     

Stepwise computational synthesis of fullerene C<Subscript>60</Subscript> derivatives. Fluorinated fullerenes C<Subscript>60</Subscript>F<Subscript>2<Emphasis Type="Italic">k</Emphasis></Subscript>

Reactions of fullerene C₆₀ with atomic fluorine are studied by the unrestricted broken spin symmetry Hartree-Fock (UBS HF) approach implemented in semiempirical codes based on the AMI technique. The calculations are focused on a successive addition of a fluorine atom to the fullerene cage following the indication of the highest chemical susceptibility of the cage atom, which is calculated at each step. The proposed computational synthesis is based on the effectively unpaired-electron concept of the chemical susceptibility of fullerene atoms. The obtained results are analyzed from the standpoints of energy, symmetry, and the composition abundance. A good fitting of the data to experimental findings proves a creative role of the suggested synthetic methodology.     

Dynamics of topological solitons in two-dimensional ferromagnets

Dynamical topological solitons are studied in classical two-dimensional Heisenberg easy-axis ferromagnets. The properties of such solitons are treated both analytically in the continuum limit and numerically by spin dynamics simulations of the discrete system. Excitation of internal mode causes orbital motion. This is confirmed by simulations.     

Continuous symmetry of C60 fullerene and its derivatives

Conventionally, the I(h) symmetry of fullerene C(60) is accepted, which is supported by numerous calculations. However, this conclusion results from the consideration of the molecule electron system, of its odd electrons in particular, in a closed-shell approximation without taking the electron spin into account. Passing to the open-shell approximation has led to both the energy and the symmetry lowering up to C(i). Seemingly contradicting to a high-symmetry pattern of experimental recording, particularly concerning the molecule electronic spectra, the finding is considered in this Article from the continuous symmetry viewpoint. Exploiting continuous symmetry measure and continuous symmetry level approaches, it was shown that formal C(i) symmetry of the molecule is by 99.99% I(h). A similar continuous symmetry analysis of the fullerene monoderivatives gives a reasonable explanation of a large variety of their optical spectra patterns within the framework of the same C(1) formal symmetry exhibiting a strong stability of the C(60) skeleton. TOC color pictures present chemical portrait of C(60) in terms of atomic chemical susceptibility (Sheka, E. Fullerenes: Nanochemistry, Nanomagnetism, Nanomedicine, Nanophotonics; CRC Press: Taylor and Francis Group, Boca Raton, 2011).     

Sequence of Phase Transitions in Solid Mbba

Combined neutron diffraction and Raman scattering measurements were carried out on a series of different phases of the same MBBA sample. The change in the diffraction patterns and in the optical spectra are used to indicate the transitions between the different phases investigated in the whole temperature range of interest. Besides the isotropic and nematic liquid crystalline phases, 7 different solid structures were found and a schematic phase diagram was constructed to show the thermal procedur for producing these phases.     

Neutron scattering study of reduced graphene oxide of natural origin

This paper presents a direct confirmation of graphene-like configuration and first suggests the chemical composition of basic structural elements of shungite attributing the latter to reduced graphene oxide nanosheets with an average 11:1:3 (C:O:H) atomic content ratio.     

玫瑰红与介孔二氧化硅生物光敏复合体的激发态性质

以光动力治疗药物玫瑰红( Rose Bengal,RB)与孔径为2.7nm的介孔二氧化硅MCM-41为主体材料进行结构组装,制备了具有生物光敏功能的介孔复合载体.对介孔复合载体的性质进行了表征,通过紫外吸收和荧光光谱对玫瑰红RB在介孔孔道内的光学性质进行了分析.由于介孔道表面与RB的相互作用,不同结构和性质的内孔道中的...     

Influence of the structure of fullerene molecules on their clusterization in the crystalline matrix

The influence of the processes occurring during clusterization of fullerene molecules in solutions on their nonlinear optical properties has been considered. A new derivative of fullerene C₆₀, namely, monofulleropyrrolidine containing a specific group, which is known as sterically hindered phenol, has been analyzed using the previously proposed criteria, i.e., an empirical criterion, which is involved in the analysis of the emission spectrum of the frozen solution, and a theoretical criterion, which is based on the quantumchemical calculation. The performed experimental investigations of the frozen solution of this fullerene derivative in toluene completely confirmed the conclusions following from the results of theoretical calculations and demonstrated a low efficiency of the clusterization of fullerene molecules in this solution and, correspondingly, a low efficiency of its nonlinear optical response. It has been shown that quantum-chemical calculations can serve as the basis for prior testing of possible fullerene derivatives for the subsequent controllable chemical synthesis of a derivative with required properties.