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排序方式: 共有58条查询结果,搜索用时 15 毫秒
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P. Calandra D. Lombardo A. Pistone V. Turco Liveri S. Trusso 《Journal of nanoparticle research》2011,13(11):5833-5839
In this paper a novel hybrid approach to synthesise composite nanoparticles is presented. It is based on the laser ablation
of a bulk target (Yb) immersed in a reversed micellar solution which contains nanoparticles of a different host material (TiO2 nanoparticles) previously synthesised by chemical method. This approach thus exploits the advantages of the chemical synthesis
through reversed micellar solution (size control, nanoparticle stabilisation), and of the laser ablation (“clean” synthesis,
no side reactions). Central role is played by the microscopic processes controlling the deposition of the ablated Yb atoms
onto the surface of TiO2 nanoparticles which actually behave as nucleation seeds. The structural features of the resulting Yb@TiO2 composite nanoparticles have been studied by Transmission Electron Microscopy, whereas their peculiar optical properties
have been explored by UV–Vis spectroscopy and steady-state fluorescence. Results consistently show the formation of Yb and
TiO2 glued nanodomains to form nearly spherical and non-interacting nanoparticles with enhanced photophysical properties. 相似文献
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A detailed investigation of the electronic structure of Pd(l 11) clean surface is presented in terms of a LCAO band model. Results including surface bands and local densities of states are given and a comparison with recently performed photoemission experiments is presented. For hω = 21.2 eV we find that the angle resolved distribution curves can be explained in terms of initial state density and k∥ conserving transitions. For lower photon energies a mixture of bulk transition calculations and surface density of states seems more appropriate. Comparison with previous theoretical work is also presented. 相似文献
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The behaviour of the hole number in YBCO systems as a function of the oxygen deficiency x is studied theoretically by calculating the density of electron states for several different superstructures formed by periodic arrangements of the oxygen vacancies. The characteristic features of the electronic properties for chain copper sites with different coordination are pointed out and their relevance in determining the number of carriers for oxygen planes is illustrated. It is shown that the curve of the hole number as a function of x shows plateaus and jumps similar to those found in the Tc versus x curves if the de-oxygenation process takes place by forming fragmented chains. Structures formed by filled and empty chains only give a smooth hole behaviour as a function of the composition. The results of the numerical calculations can be understood by a simple model giving the Fermi energy shift in terms of the concentrations of Cu(1) sites with different coordination. 相似文献
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J. Herrera Gallego C.E. Castellano A.J. Calandra A.J. Arvia 《Journal of Electroanalytical Chemistry》1975,66(3):207-230
Results obtained with differently prepared gold electrodes in acid solutions containing chloride ion at temperatures ranging from 22 to 65°C are reported. Potentiostatic techniques and rotating disc electrodes were employed. The anodic dissolution, the onset of passivity and the cathodic deposition of the metal are investigated under different experimental conditions. The anodic dissolution of Au is discussed in terms of possible reaction mechanisms involving the participation of different adsorbed species. The onset of passivation is related to the depletion of chloride ion at the reaction interface. The experimental voltammograms can be reporduced by means of an equation which considers the diffusion of chloride ion, the activation polarization related to the dissolution of Au and the establishment of passivity. 相似文献
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S. Nannarone P. Perfetti C. Quaresima C. Quaresima A. Savioa C.M. Bertoni C. Calandra F. Manghi 《Solid State Communications》1980,34(6):409-412
We present the results of an investigation of the electronic structure of heterojunctions formed by deposition of Germanium on Si (lll) surfaces. Energy Loss Spectra for various Ge coverages have been taken and compared with theoretical calculations. The results indicate that the interface is abrupt and at low coverages Ge is deposited uniformly on the substrate. Above 2 monolayers coverage modifications in the electronic structure appear probably caused by the growth mechanism. 相似文献
10.
The preparation procedure for nanoparticles of the water-soluble salts Na2S and ZnSO4, two commonly used reagents to synthesise ZnS nanoparticles, by evaporation of volatile components of salt-containing water-in-oil
microemulsions is described. In suitable conditions, the evaporation leads to the formation of dry salt–surfactant composites
and to the formation of Na2S or ZnSO4 nanoparticles. It was found that the salt–surfactant composites can be totally redissolved in a dry apolar organic solvent
allowing the formation of virtually water-free solutions containing a considerable amount of the water-soluble salts. The
presence of nanoparticles in these solutions and in the composites has been proved by small-angle X-ray scattering and transmission
electron microscopy, respectively. By mixing these solutions, the solid–solid reaction between Na2S and ZnSO4 nanoparticles leading to the formation of very small-sized ZnS nanoparticles has been ascertained by UV spectrophotometry.
Received: 09 February 2001 Accepted: 19 March 2001 相似文献