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Sökning: WFRF:(Li Y) > Kinesiska

  • Resultat 1-10 av 11
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1.
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2.
  • He, Sailing, et al. (författare)
  • Synchrotron radiation photoemission study of Yb2.75C60
  • 2005
  • Ingår i: Wuli xuebao. - : Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences. - 1000-3290. ; 54:3, s. 1400-1405
  • Tidskriftsartikel (refereegranskat)abstract
    • The Yb275C60 thin film was prepared and studied by using the synchrotron radiation ultraviolet photoemission spectroscopy(PES) in an ultrahighvacuum system. The spectral line obtained in the range between the Fermi level and ~5 eV binding energy consists of those lines from the valence band (the molecular orbital LUMO, HOMO and HOMO1 derived energy bands of C60) and core levels(Yb 4f7/2 and 4f5/2). Taking into account the variations of the photoinization cross sections of C 2p and Yb 4f with different photon energies, we have measured the photoemission spectra under the condition of varying photon energies, and carried out simulations to deduce the component contributions. The peak positions, widths and intensities for the components are obtained quantitatively. The results reveals that the photoemission of 4f electrons has a significant intensity with the photon energies larger than ~300 eV, and that the measured spectra depart drastically from the density of states of the valence band. To observe the valence band structure, one should carry out the PES measurements by using photons with energies less than 300 eV. The photoionization crosssection oscillation is also observed in Yb275C60 with almost the same oscillation period as that for pure C60 However, the oscillation amplitude is obviously smaller than that for pure C60, which reveals that the chemical environment of C60 in compounds has nonnegligible effects on the photoionization crosssection oscillation phenomenon.
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3.
  • Li, H. N., et al. (författare)
  • Valence band photoemission of Yb2.75C60
  • 2004
  • Ingår i: Wuli xuebao. - : Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences. - 1000-3290. ; 53:1, s. 244-247
  • Tidskriftsartikel (refereegranskat)abstract
    • Valence-band electronic density of states of Yb2.75C60 thin films was measured by the ultraviolet photoemission spectrum technique. The phase-pure Yb2.75C60 sample was characterized by the C 1s XPS measurements. The result indicates Yb2.75C60 has no Fermi edge and thus is semiconductor. The hybridization between 6s state of Yb and the LUMO band of C60 cannot be considered to be negligible. Some Yb 6s electrons occupy the Yb-C60 covalent band in Yb2.75C60.
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4.
  • Fan, Y., et al. (författare)
  • Mechanical preparation of nano titanium dioxide powder and its optical properties
  • 2007
  • Ingår i: Journal of the Chinese Ceramic Society. - 0454-5648. ; 35:7, s. 832-837
  • Tidskriftsartikel (refereegranskat)abstract
    • mechanical preparation of the nano-sized particles of TiO2 powder by a stirred bead mill was investigated. The particle sizes of the ground products were determined by the acoustic particle sizer, the nitrogen gas adsorption method and a scanning electron microscopy. The diameter of the nano-sized particles, which were obtained after milling for 7 h, is about 50 nm and the specific surface area is up to 70 m2/g. The surface and structure of the samples have been investigated with X-ray diffraction. It is indicated that an intense comminution in the mill leads to a progressive loss in crystallinity of TiO2. The catalytic degradation of methyl orange in water was also studied by a photometer. The results show that the nano-sized particles of TiO2 powder prepared by milling possess photocatalysis effect and are capable of absorption of ultraviolet radiation
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5.
  • Liang, G-B, et al. (författare)
  • Modified regularization method applied to the inversion of particle size distribution from light scattering data
  • 2006
  • Ingår i: Guangdian Gongcheng. - 1003-501X. ; 33:12, s. 44-49
  • Tidskriftsartikel (refereegranskat)abstract
    • Laser particle size analyzer is one of the instruments for particle size analysis. Recent developments focus on various algorithms for particle size analysis via light energy distribution based on the Mie scattering theory in the laser analyzer. The determination of the particle size distribution (PSD) from the analyzer requires the inversion of the Fredholm integral equation of the first kind. This equation is an ill-posed one, which can be analyzed by effective algorithms. This paper presents a modified regularization method applied to the inversion of the PSD with the independent models. The Generalized Cross-Validation (GCV) method was used for the selection of a regularization parameter. The Successive Over-Relaxation (SOR) iterative method was applied to improve the exactness and stability of the convergent result. The simulation with the models was carried out. The simulated results are in a good agreement with the data measured from nine standard particulate samples as well as their mixtures. It is indicated that this method can be feasible and effective for the simulation of the PSD from the corresponding light scattering data.
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6.
  • Ma, Y., et al. (författare)
  • Theoretical studies on electronic transport properties of six-membered heterocyclic molecules
  • 2006
  • Ingår i: Wuli xuebao. - : Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences. - 1000-3290. ; 55:4, s. 1974-1978
  • Tidskriftsartikel (refereegranskat)abstract
    • By applying the elastic scattering Green's function theory in combination with the hybrid density function theory, the electronic transport properties of molecular junctions constructed by the six-membered heterocyclic molecules, pyridazine-2, 5-dithiol, pyrazine-2, 5-dithiol, and pyrimidine-2, 5-dithiol, have been studied. For the heterocyclic molecule pyridine, the influence of the terminal atoms on the current-voltage characteristics has also been obtained. We have accurately determined the coupling constant between the molecule and electrodes by using the frontier molecular orbital theory and the perturbation method. The numerical results show that pyridazine-2,5-dithiol has higher current and conductance, while the conductance of pyrimidine-2, 5-dithiol is very small when the bias voltage is lower than 4V. The conductivity of the molecule pyridine with selenium atom as the terminal atom is higher than that with oxygen atom or sulfur atom.
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7.
  • Shi, F., et al. (författare)
  • Synthesis and properties of a new donor model compound for PSII
  • 2004
  • Ingår i: Gaodeng xuéxiào huàxué xuébào. - 0251-0790. ; 25:9, s. 1666-1672
  • Tidskriftsartikel (refereegranskat)abstract
    • As a model compound for redox components on the donor side of photosystem II (PS II) in green plants, a supramolecular complex 2 was synthesized and characterized. In this complex, two {[(2-hydroxy-3-(morpholin-4-ylmethyl)-5-tert-butyl-benzyl)(pyridyl-2-methyl)amino]methyl} arms are linked to the ortho-positions of a phenol which is expected covalently to be linked to Ru(II) tris-bipyridine through an amide bond. The arms on the substituted-phenol can coordinate two Mn(III) ions. The structure of complex 2 was confirmed by electrospray ionization mass spectrometry (ESI-MS) and 2D-NMR (gCOSY, HSQC and HMBC). Its photochemical and electrochemical properties were studied. The results showed that the MLCT band of the compound was red-shifted compared to that of [Ru(byp)(3)](2+) and the luminescence quantum yield was enhanced. In addition, the oxidation potential of ruthenium was higher than the phenol(+)/phenol and Mn(III, IV)/Mn(III) which was consisted with the electron transfer sequence of the donor side of PS II in nature. All these showed that this compound was a good model to mimic the donor side of PS II.
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8.
  • Shi, F., et al. (författare)
  • Synthesis and spectral properties of a new ruthenium(II) tris-bipyridine with four ester groups and substituted phenol
  • 2004
  • Ingår i: Huaxue xuebao. - 0567-7351. ; 62:7, s. 713-719
  • Tidskriftsartikel (refereegranskat)abstract
    • A new ruthenium(II) complex (1) with four ester groups have been designed and synthesized, in which a phenol substituted by {[(2-hydroxy-3-(morpholin-4-ylmethyl)-5-tent-butylbenzyl) (pyridyl-2-methyl) amino]methyl} groups was covalently linked to ruthenium (II) tris-bipyridine. The structure of complex 1 was characterized by electrospray ionization mass spectrometer (ESI-MS) and 1D-NMR, 2D-NMR (gCOSY, HSQC and HMBC) spectra. The electrochemical and spectral properties were also studied. Introduction of the four carboxyl acid groups and the donor ligand tuned the spectra and the redox properties of compound 1. The MLCT transition was turned from 451 to 474 nm and the complex had long lifetime of the (MLCT)-M-3 state emission. Moreover, the oxidation potential of Ru3+/Ru2 + of compound 1 was similar to 360 mV higher than that of [Ru(bpy)(3)](2+) which would enhance the driving-force of electron transfer. These results showed that the compound 1 had proper redox potentials and was suitable for being used as photosensitizer of solar cell.
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9.
  • Yang, Y., et al. (författare)
  • A new smoothing algorithm and its application in gravitational lensing
  • 2008
  • Ingår i: Acta Astronomica Sinica. ; 49:4, s. 359-369
  • Tidskriftsartikel (refereegranskat)abstract
    • We develop a new smoothing algorithm for computing surface densities from 3D numerical simulation samples. This algorithm is based on DWT (discrete wavelet transform) method. We test the algorithm by applying it to two gravitational lensing simulation samples which are generated by monte-carlo method and have different mass resolution, the results show our algorithm can successfully reconstruct the surface density of lens. We also compute the critical curves and caustics of lens samples, the results show that they can fit the theoretic curves very well. We test three different wavelet bases and compare them, including Daub4, Daub6 and B-spline 3th. Our algorithm is very fast and is suitable for high resolution N-body simulations.
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