在隐藏的光合作用加成反应中富勒烯与胺之间的相互作用之重要性(英文)

pacc:8100Donor-acceptor(DA)contributionintothe intermolecularinteraction(IMI)offullerenes(C60andC70below)withaminesisevidently dominant.AcomplexIMIpotential,multi-well ingeneralandtwo-wellinparticular,governs thefinalproductformationinthegroundstate[1].If…     

Effect of laser irradiation of C-V characteristics of electrodeposited Ag/Tl-2223/CdSe hetero-nanostructures

One of the innovative technological directions for the high-temperature superconductors has been persued by fabricating the heteroepitaxial multilayer structures such as superconductor-semiconductor heterostructures. In the present investigation, metal/superconductor/semiconductor (Ag/Tl-2223/CdSe) hetero-nanostructures have successfully been fabricated using dc electrodeposition technique and were characterized by X-ray diffraction (XRD), full-width at half-maximum (FWHM) and scanning electron microscopy (SEM) studies. The measurement of junction capacitance as a function of biasing voltage was used for the estimation of junction built-in-potential (V _D) and to study the charge distribution in a heterojunction. The Mott-Schottky plots were measured for each junction in dark and under the photo-irradiation. The effect of laser irradiation on C-V characteristics of hetero-nanostructure has been studied.     

Kinetics and mechanism of oxidation of copper(I) ions with thiuram disulfide

The kinetics of the oxidation of copper(I) perchlorate with thiuram disulfide (tds) in acetonitrile and its mixtures with benzene or ethyl bromide have been investigated. It has been shown that the rate of the reaction is limited by the inner-sphere transfer of an electron from the copper(I) ion to tds in a complex of the type [Cu^I(tds)]⁺. The subsequent dissociation of the anionradical tds —proceeds rapidly and leads to the formation of copper(II) dithiocarbamate which is recorded in the absorption spectra and by EPR. The rate constant of electron transfer has been determined (3·10^–4sec^–1) and it was found that it is practically independent of the polarity of the medium. The absence of such a correlation is attributed to the negligible energies of reorganization of the solvent in the inner-sphere electron transfer.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 24, No. 4, pp. 450–455, July–August, 1988.     

Exciton-phonon interaction and energy transfer in benzene and isotopically impure deuterobenzene crystals

Absorption and fluorescence of pure and isotopically substituted benzene crystals are reported for the range 4.2–20°K. The energy of electron- and vibron-phonon interactions and the probability of respective optical transitions are determined. The pronounced asymmetry of phonon sidebands of absorption and luminescence spectra is found. The kinetic analysis of isotopically impure crystal spectra gives the trap-trap energy transfer probability and the energy dependence of the electron-phonon coupling coefficient.     

Graphene-nanotube structures: Constitution and formation energy

A new class of carbon nanostructures is considered: covalently (or molecularly) bound graphene and carbon nanotube fragments. As found using semiempirical computations and molecular dynamics methods, the structures formed by bonding nanotube edge atoms to a planar segment of a graphene nanofragment or its edge atoms to nanotube atoms arranged at the element of cylinder and graphene nanoribbons attached to a nanotube by van der Waals forces along the nanotube are the most energetically stable systems.     

Fractals of graphene quantum dots in photoluminescence of shungite

Viewing shungite as loosely packed fractal nets of graphene-based (reduced graphene oxide, rGO) quantum dots (GQDs), we consider photoluminescence of the latter as a convincing proof of the structural concept as well as of the GQD attribution to individual rGO fragments. We study emission from shungite GQDs for colloidal dispersions in water, carbon tetrachloride, and toluene at both room and low temperatures. As expected, the photoluminescence of the GQD aqueous dispersions is quite similar to that of synthetic GQDs of the rGO origin. The morphological study of shungite dispersions shows a steady trend of GQDs to form fractals and to drastically change the colloid fractal structure caused by the solvent exchange. Spectral study reveals a dual character of the emitting centers: individual GQDs are responsible for the spectra position while the fractal structure of GQD colloids ensures high broadening of the spectra due to structural inhomogeneity, thus causing a peculiar dependence of the photoluminescence spectra on the excitation wavelength. For the first time, photoluminescence spectra of individual GQDs were observed in frozen toluene dispersions, which paves the way for a theoretical treatment of the GQD photonics.     

Fullerene model of silicon nanofibers

A computational (quantum-chemical) experiment has been performed on constructing a silicon nanofiber by gas-phase deposition. A model of two-step polymerization has been proposed in which a fullerene Si₆₀ molecule serves as the main structural unit. The formation of oligomers of the molecule containing from three to eight molecular units explains the discrete values of the fiber width observed experimentally. The formation of a “rouleau” of oligomers leads to fiber growth in terms of length. It is shown that both steps are favorable in energy with the decisive superiority of a high-spin state, which poses the question of considering silicon nanofibers to be molecular magnets.