A FLATTENED OCTAHEDRON – THE METAL ENVIRONMENT IN COMPLEXES WITH PYRROLYL-SUBSTITUTED NITROXIDE DIRADICALS

Journal of Structural Chemistry - The structures of Ni(II), Cu(II), and Zn(II) complexes with anions of 2,5-pyrrolyl-disubstituted nitronyl nitroxide (L1) and iminonitroxide (L2) diradicals (HL1 is...     

Plasmon resonance in a nanosphere

The phenomenon of plasmon resonance in a nanosphere and a nanospheroid is considered. As is known, this phenomenon does not depend explicitly on the size of these nanoparticles. However, it is shown that, actually, the resonance conditions are determined by the diameter of the nanosphere and by the length of the major axis of the nanospheroid.     

Creation of electron-positron pairs in the collision of heavy atomic nuclei. Systematic quantum-mechanical approach

The creation of electron-positron pairs in the collision of two heavy nuclei is considered. A systematic quantum-mechanical approach is developed for the complete electron-nuclear system. The finite size of the nuclei and the possible resonances of the superheavy compound nucleus formed from the initial nuclei are taken into account. The energetic approach known in the theory of the breakdown of quasisteady systems is generalized to the case of the collisional problem. This approach is combined with perturbation theory for the complete electron-nuclear system. The rearrangement of the negative-continuum spectrum is taken into account using the procedure of [14], which is generalized with the aim of introducing additional conditions, in particular, the condition associated with correct choice of the zero approximation. The method is the same for Z < Z_cr and Z > Z_cr, where Z_cr is the minimum nuclear charge at which spontaneous pair creation is possible. The contribution of the spontaneous channel to the amplitude of the process is automatically taken into account.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 97–107, August, 1990.     

Study of the laser-initiated chlorination of methyltrichlorogermane

Conclusions The high selectivity of the chlorination of CH₃GeCl₃with the formation of CH₂ClGeCl₃ by the action of a UV laser is independent of the emission wavelength in the range from 193 to 308 run. The quantum yield is not less than 10².Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2167–2170, September, 1988.     

Electronegativity in Quantum Chemistry

The possibility is discussed for determination of chemical potential (electronegativity) of an electron-nucleus system in terms of the quantum-mechanical density functional theory (DFT). The principle of complete leveling of chemical potentials of natural orbitals, formulated in the framework of DFT, cannot be regarded now as justified. The calculation of electronic chemical potential via difference schemes still remains the only procedure suitable for estimation of this quantity by quantum-chemical methods.     

Atropisomerism of phosphorus-containing N-aryl carbamates. Experimental and computational data

Studies by ¹H NMR spectroscopy and X-ray diffraction analysis revealed hindered rotation of the aromatic substituent about the C_Ar—N bond in ortho-substituted (except for o-fluorine-substituted) phosphorus-containing carbamates. The energy barriers to rotation (G _c ) and coalescence temperatures (T _c) determined by the coalescence method increase with increasing volume of the ortho substituent. Conformations resulting from rotation of the ortho-substituted aryl group about the C_Ar—N bond were analyzed by quantum-chemical methods, potential curves were constructed, and differences between the conformational energies and the heights of rotation barriers were estimated. The theoretical rotation barriers change in parallel with the experimental values of G _c ; however, the theoretical values are much smaller in magnitude.     

Encapsulation of diagnostic dyes in the polysaccharide matrix modified by carbon nanotubes

The effect of carbon nanotubes (CNTs) on the morphology and properties of alginate hydrogel was studied. The addition of CNTs leads to a change in the structural characteristics of the hydrogel, which is expressed in a decrease in the pore size and gaining a more uniformity by the internal structure. To study the encapsulating properties of the designed compositions, a set of dyes was used that are traditionally applied for testing the drug release rate. It was found that the CNTs do not affect the efficiency of inclusion and the release rate of the anionic and neutral dyes. The change in the kinetics of cationic dye release is caused by the reinforcing effect of the CNTs on the alginate hydrogel and a change in its morphological characteristics.

     

Very slow surface plasmons: Theory and practice (Review)

The theory and practical applications of very slow (antisymmetric) optical plasmons are described. These plasmons can exist on thin metal films and filaments and (as standing waves) on metal spheres and ellipsoids. The material presented here extends the conventional concepts of electromagnetic modes of spaces, probability of spontaneous emission, construction of optical images, optical focusing, and the photon momentum. The reviewed achievements in this field have been obtained in the last years. The problem of the photon momentum in a medium has been a subject of irreconcilable disputes for nearly 100 years, beginning with Minkowski and Abraham’s famous papers. Various practical applications are considered, including experiments with the significant enhancement of atom spontaneous emission into a plasmon field mode of a nanoparticle; experiments on focusing optical radiation into a spot much smaller than the diffraction-limited one (the so-called almost ideal Pendry lens, which produces an image with details much smaller than the light wavelength); and, finally, a greatly increased (by factors of 10, 100, or more) photon momentum in plasmon.