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1.
The reaction of C70 by ultrasonication with various oxidants such as 3-chloroperoxy benzoic acid (Fluka 99%), 4-methyl morpholine N-oxide (Aldrich 97%), chromium (VI) oxide (Aldrich 99.9%), and oxone® monopersulfate compound, at room temperature causes the oxidation of fullerene [C70(O)n] (n=1–2 or n=1). The FAB-MS, UV–visible, FT-IR spectra, and HPLC analysis confirmed that products of fullerene oxidation are [C70(O)n] (n=1–2 or n=1). 相似文献
2.
The energy spectrum of the C60 fullerene has been calculated in terms of the Shubin-Vonsovskii-Hubbard model using an approximation of static fluctuations.
Based on the spectrum, the optical absorption bands at 4.84, 5.88, and 6.30 eV observed experimentally have been successfully
explained. It has been concluded that the model used is applicable for the calculation of the energy spectrum and the energy
properties of other nanosystems, such as fullerenes of higher orders, carbon nanotubes, and grafen planes. 相似文献
3.
The energy dependent ionization cross sections corresponding to the formation of singly, doubly and triply charged cations
in the electron impact ionization of C70 are evaluated employing a semiempirical formulation at the incident electron energies of 100 and 200 eV. The integral ionization
cross sections have also been calculated in the energy range varying from ionization thresholds to 1000 eV which revealed
a satisfactory agreement with the available experimental and the theoretical data. The ionization rate coefficients corresponding
to the various cations have also been evaluated using the presently calculated ionization cross sections and Maxwell-Boltzmann
energy distributions. 相似文献
4.
Song Guo 《Surface science》2007,601(4):994-1000
Scanning tunneling microscopy (STM) is used to characterize partial monolayers of C60, C70, and C84 adsorbed on the Au(1 1 1) surface at room temperature and under ambient conditions. A high degree of structural polymorphism is observed for monolayers of each of these fullerenes. For C60, three lattice packings are observed, including a previously unreported 7 × 7 R21.8° structure that is stabilized by adjacent surface step defects. For C70, two lattice packings are observed, and analysis of molecular features in STM images allows molecular binding geometry to be determined. In one of the two observed lattice structures, C70 molecules align their long axis along the surface normal, while in the other, molecules align parallel to the surface and along a gold lattice direction. The parallel geometry is also preferred for isolated and loosely packed molecules on the surface. C84 exhibits a large number of lattice orientations and no long-range order, and likely binds incommensurately on Au(1 1 1). Time series of images of partial C70 monolayers show progressive surface modification as a result of perturbation by the STM tip; this is in contrast to the behavior of C60, where alterations in surface structure at room temperature are thermally driven. 相似文献
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The reactions of fullerene[C60] with 2′-azidoethyl 2,3,4,6-tetra-O-acetyl-α-d-mannopyranoside (2a) and 2′-azidoethyl 2,3,4,6-tetra-O-acetyl-β-d-galactopyranoside (2b) under ultrasonic irradiation cause the cycloaddition of 2′-azidoethyl glycosides to fullerene[C60] and lead to d-glycosyl fullerene[C60] derivatives 3a and 3b, respectively. The glycosyl fullerene[C60] derivatives were characterized by 1H and 13C NMR, UV–vis, FAB-MS, FT-IR spectra and were a 1:1 glycoside fullerene [C60]-adduct. 相似文献
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Hong Liang Shunfu Xu Weihui Liu Yueqiang Sun Xiangfa Liu Xinqing Zheng Sen Li Qiang Zhang Ziliang Zhu Xiaochun Zhang Chengguo Dong Chun Li Guang Yuan Hitenori Mimura 《Physics letters. A》2013
The impact of alkali-metal (Li/Na/Cs) adsorption on work function of fullerenes C60 and C70 was investigated by first-principles calculations. After adsorption, the work functions of fullerenes C60 and C70 decrease distinctly and vary linearly with the electronegativity of the alkali metal elements, and the positions where the alkali atoms are adsorbed considerably influence the work functions. On the contrary, a vacancy defect elevates the work functions of the fullerenes C60 and C70. The variation in the work functions rests with variation in Fermi level (which are attributed to charge transfer) and variation in vacuum levels (which are attributed to the induced dipole moments). Moreover, alkali-metal adsorption can also improve the electric conductivity of a fullerene mixture of C60 and C70. 相似文献
9.
Y.-P. Sun S. Gavrilyuk J.-C. Liu C.-K. Wang H. gren F. Gelmukhanov 《Journal of Electron Spectroscopy and Related Phenomena》2009,174(1-3):125
We present a dynamical theory of nonlinear absorption and propagation of a laser pulse train that contains 20 subpulses with an individual pulse width of 100 ps. It is shown that the accumulative nonlinearity and the reverse saturation absorption play important roles in the optical limiting performance and pulse shaping. When the incident field is not too strong, the population transfer reveals a slow response process, and the periodic sequence of short light pulses can be regarded as a continuous long pulse. The general theory is applied to fullerence C60, which is a popular reverse saturable absorption material and a good limiter because of its larger excited-state absorption cross-section compared with that of the ground state. The propagation of the front subpulses is mainly affected by the linear transition between the ground state and the first excited singlet state, while the latter subpulses are attenuated by the excited-state absorption. Moreover, these two different kinds of absorption mechanisms result in different radial distributions for different subpulses. The pulse propagation is studied by solving numerically the coupled rate equations and the propagation equation of the optical pulse intensity, using experimental parameters as input. We suggest a new method to measure the lifetime of the triplet state. 相似文献
10.
运用基于密度泛函理论和基于非平衡格林函数的第一性原理方法研究了富勒烯C20分子及连接电极构成的C20分子器件的电子结构及电子输运性质.构建了三个基于C20分子的嵌入K和Si原子的电子输运系统,并得到了电子透射谱和分子轨道分布.分析了三种器件的电子结构和输运性质的产生原因,说明C20分子器件的电子传导主要集中在外壳.在C20分子空笼中嵌入K和Si原子后,其电子输运仍然主要集中于富勒烯C20的外壳.
关键词:
20分子')" href="#">富勒烯C20分子
电子结构
电子传导 相似文献
11.
Darakhshan Qaiser 《Optics Communications》2010,283(18):3437-693
Fullerene C60 thin films on glass substrate (around 2000 ? thickness) were prepared by thermal evaporation technique. The structural, surface morphology and optical properties of the films were studied. The optical properties of fullerene C60 were investigated in the spectral range 200 nm to 900 nm using a UV-Vis spectrophotometer at room temperature as well as at liquid nitrogen temperature (77 K). The optical band gap at room temperature is found to be 2.30 eV, which gradually decreases with lowering the temperature and reaches to 2.27 at 77 K. The thickness and refractive index of fullerene C60 film were calculated by ellipsometry. From the X-ray analysis, we have calculated the grain size, dislocation density, number of crystallite per unit area, and strain of the film at room temperature. The surface morphology of film was analyzed by scanning electron microscope (SEM). The present result show that the fullerene C60 film becomes more conducting at low temperature. 相似文献
12.
Xu Bingshe Han Peide Liu Xuguang Li Tianbao Hideki Ichinose 《Solid State Communications》2005,133(6):353-356
Theoretical calculations via a transfer matrix method (TMM) were performed to investigate the possibility of fullerene/AlN multilayer films acting as one-dimensional (1D) photonic band gap (PBG) crystals. The response within and out of the periodic plane of (C60, C70)/AlN multilayers was studied. (C60, C70)/AlN multilayer films presented incomplete PBG behavior in UV region. C60/AlN multilayers with two pairs of 49 nm-C60 and 21 nm-AlN layers exhibited a high reflectivity of 90.4% at a wavelength of about 200 nm. As a consequence, this photonic crystal may be important for achieving materials with an incomplete band gap in the UV region. 相似文献
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Dmitri V. Konarev Dmitri V. Lopatin Alexey V. Umrikhin Gunzi Saito Alexey L. Litvinov 《Journal of Physics and Chemistry of Solids》2005,66(5):711-715
A new molecular complex of C60 with tetrabenzo(1,2-bis[4H-thiopyran-4-ylidene]ethene), Bz4BTPE C60 (1) has been obtained. The complex has a layered structure in which closely packed hexagonal layers of C60 alternate with the layers composed of Bz4BTPE molecules. The complex has a neutral ground state according to UV-vis-NIR spectrum. It has been found that single crystals of 1 show low ‘dark’ conductivity of σ∼10−10 (Ω cm)−1. A 102 increase in photocurrent has been observed upon illuminating the crystal with white light. Photoconductivity of 1 is sensitive to magnetic field with B0<1 T and increases up to 5% in magnetic field. The photoconductivity spectra of the complex indicate that free charge carriers are generated in the UV-visible range mainly by the Bz4BTPE excitation (the peaks at 622, 562, 472 and 348 nm) with a possible contribution of charge transfer excitations between neighboring C60 molecules (the peak at 472 nm). 相似文献
15.
Fang Zhang 《Journal of luminescence》2010,130(5):787-791
Different C60 aggregates, i.e. nanoparticles, clusters of nanoparticles and microcrystals in room-temperature solutions, are reported to account for the colors of fluorescence emissions centered at 440, 575 and 700 nm, respectively. And the configurations of C60 aggregation created in solutions are revealed to be closely associated with the characteristic interactions between C60 and solvent molecules. On this basis, aggregation behaviors and thus induced optical properties of C60 have been tentatively controlled through adopting solvent mixtures. 相似文献
16.
The quenching behavior of the triplets of C60 by various aniline derivatives (1a-d and 2a-e) was investigated by means of laser flash photolysis in benzonitrile at 293 K. Electron transfer process was proposed to be the main mechanism because of the direct detection of radical ions of aniline derivatives and C60 in time-resolved transient absorption spectra. The quenching rate constants (kq) of by different substrates determined at 740 nm approach or reach the diffusion-controlled limit. DFT method was employed to calculate the unknown oxidation potentials of substrates in solution. With these Eox values, free energy changes (ΔG) were obtained through Rehm-Weller equation. Dependence of observed quenching rate constants on the free energy changes further indicates the photoinduced reactions between 3C60* and substrates proceed through an electron transfer mechanism. Obtained kq values for the aniline derivatives are impacted obviously by ground-state configurations and the kinds substituents quantified by Hammett σ constant. Good correlation between log kq and σ values conforms to the empirical Hammett equation. A more negative ρ value (−3.356) was gained for anilines (2a-e) than that of N,N-dimethylanilines (1a-d) (−1.382), which suggests a more susceptible reactivity for the former substrates. Charge density distribution of reaction center “N” originated from quantum calculation supports this suggestion. In addition, a relationship between quenching rate constants and solvent viscosity was gained from C60/dimethyl-p-toluidine system in altered mixtures of acetonitrile and toluene. 相似文献
17.
S BugaV Blank Å FranssonN Serebryanaya B Sundqvist 《Journal of Physics and Chemistry of Solids》2002,63(2):331-343
C60 and C70 fullerenes polymerized under pressures between 9.5 and 13 GPa and temperatures between 670 and 1850 K were investigated by differential scanning calorimetry (DSC) in the range 240-640 K. Endothermal heat effects were observed with a peak maximum just below 540 K, a temperature characteristic for breakdown of (2+2) intermolecular links in dimers, 1D and 2D polymers. Exothermal effects, starting from 380 K, were observed for the first time in polymeric fullerenes. These effects are attributed to relaxation processes and to breakdown of other types of intermolecular bonds such as common four-sided rings and (3+3) interlinks. 相似文献
18.
Photoemission studies reveal the existences of metallic Rb4C60 and Rb5C60 surface phases on the top layer of C60 single crystal. After Rb3C60 thin film with thickness of nanometers has formed on the (1 1 1) surface layers of the C60 single crystal, the excess deposition of Rb atoms do not induce the bulk-like face-centered cubic to body-centered tetragonal or body-centered cubic structure transitions at room temperature. The large size of C60 molecule offers the surface vacancies for the formation of Rb4C60 and Rb5C60 monolayer that is further verified by Rb 3d core-level photoemission measurements. Valence band photoemission results exhibit the surface phases are metallic. 相似文献
19.
The EPR line shape has been measured on a single crystal of ethylene diammonium chloromanganate (II) as a function of field orientation with respect to the expected two dimensional network of manganese ions. The angular variation of the linewidth may be described by the expression δH= α + β(3 cos2δ ? 1)2 with α = 20 and β = 4, and the lineshape may be described by I(H ? H0) ? F [exp (? At ? Bt ln ( (where F refers to the Fourier transform of the bracketed function) with . 相似文献
20.
In this paper SANS results on C60 solutions are presented. The data analysis allows to determine the value of the gyration radius of C60 dissolved in CS2, a solvent capable to guarantee a good contrast for the neutron probe. The study indicates that the gyration radius Rg is independent of concentration. 相似文献