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991.
K. Ohno Y. Noguchi S. Ueda J. Onoe 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,43(1-3):137-140
Optimized three-dimensional (3D) cell structures and energy bands
of fused (peanut-shaped) C60 polymers (p55 and p66) have been
investigated using the first-principles pseudopotential approach
within the local density approximation of the density functional theory.
We found that the resulting electronic structure is either metal or
semiconductor depending on the shape of the polymer chains and
the unit cell structure. 相似文献
992.
H. Jensen J. Kröger N. Néel R. Berndt 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,45(3):465-469
Clusters on surfaces have been investigated with low-temperature scanning tunnelling microscopy and spectroscopy. Constant
current spectra acquired on Ag oligomers and one-dimensional chains on a Ag(111) reveal a
single resonance peak whose energy shifts towards the Fermi level with increasing cluster size. Next, controlled and reproducible
contact between a STM tip and a C60 molecule adsorbed on Cu(100) is reported. The
transition from tunnelling to contact is discussed in terms of local heating of the tip-molecule junction. 相似文献
993.
Characterization of SiC and Si<Subscript>3</Subscript>N<Subscript>4</Subscript> nanoparticles and their aqueous dispersions 总被引:1,自引:0,他引:1
Nanoparticles of SiC and Si3N4 were previously used to obtain electroless NiP/particles nanocomposites. The incorporation process was very different, depending
on the particle: SiC tended to agglomerate and had a high incorporation level; Si3N4 particles were not aggregated, but their incorporation level was very low. To try to explain these differences, the particles
and their aqueous dispersions were characterized. Although the as-received products were both oxidized and of the identical
mean size, results showed that the size distributions and the surface oxidation products were rather different. The zeta potential
in water dispersions was similar and negative for both particles but, as the electrolyte ions were introduced, it showed a
different evolution: nitride particles retained a small negative charge and carbide was almost uncharged. The overall results
obtained in this study explain the different behavior of both ceramic particles and provide possible solutions to improve
their co-deposition with nickel. 相似文献
994.
H. Keskinen J. M. Mäkelä M. Aromaa J. Ristimäki T. Kanerva E. Levänen T. Mäntylä J. Keskinen 《Journal of nanoparticle research》2007,9(4):569-588
In this study, liquid flame spray (LFS) was used to produce titania, silver and silver–titania deposits of nanoparticles.
Titanium(IV)ethoxide (TEOT) and silver nitrate in ethanol solutions were used as precursors and sprayed into turbulent hydrogen–oxygen
flame. Production rates of 1.5–40 mg/min of titania were used with silver additions of 1, 2, 4, and 8 wt% compared to titania.
Nanoparticle deposits were collected by thermophoretic sampling at six different axial distances from the flame torch head:
3, 5, 10, 12, 15, and 20 cm, of which the all but the last one occurred inside the flame. The deposit samples were analysed
by TEM and SAED analysis. The powder samples of the particles were also collected by electric precipitator to XPS and specific
surface area analysis. Particle size and effective density after the flame in the aerosol were analysed with SMPS and ELPI.
The results from the previous studies i.e. controlling the particle size by setting the production rates of the particles
were seen to apply also for this binary system. Characterisation of the deposits showed that when the substrate is inserted
into the flame, in the beginning of the flame the deposit is formed by gas phase deposition whereas further down the flame
the particles are first formed in the gas phase and then deposited. The location of the transition from gas phase deposition
to gas phase nucleation prior to deposition depends on chemical/physical properties (e.g. thermodynamics and gas phase interactions)
of the precursor, precursor concentration in the flame and also flame temperature profile. Therefore, the deposit collection
distance from the burner also affected the collected particle size and degree of agglomeration. The two component deposits
were produced in two different ways: one-step method mixing both precursors in the same solute, and two-step method spraying
each precursor separately. The particle morphology differs between these two cases. In one-step method the primary (d
TEM) and agglomerate particle size (d
SMPS) decreased with the amount of silver addition, verifying the fact that when present, the silver has a clear effect on the
titania nanoparticle formation and growth. 相似文献
995.
R. K. Karakhanyan R. T. Malkhasyan 《Journal of Contemporary Physics (Armenian Academy of Sciences)》2007,42(6):261-263
Chain aggregates of MoO3 nanoparticles have been obtained and their polymer-like properties revealed. Chain aggregates of MoO3 nanoparticles, like polymers, form parallel packings, coils and exhibit coil-helix transition, Brownian motion, and high flexibility. 相似文献
996.
A. Tanaka R. Saito T. Kamikake M. Imamura H. Yasuda 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,43(1-3):229-232
We have performed the optical and photoelectron
spectroscopic studies of alkyl-passivated Si nanoparticles synthesized by a
solution route. The alkyl-passivated Si nanoparticle with mean diameter less
than about 2 nm exhibits a strong ultraviolet-blue photoluminescence.
Furthermore, we have directly investigated their electronic structures in
the vicinity of Fermi level by means of valence-band photoemission
measurements using synchrotron radiation. From these results, the detailed
optical properties and electronic structures of alkyl-passivated Si
nanoparticles are discussed. 相似文献
997.
Salvatore Giuffrida Guglielmo G. Condorelli Lucia L. Costanzo Giorgio Ventimiglia Raffaella Lo Nigro Maria Favazza Enrico Votrico Corrado Bongiorno Ignazio L. Fragalà 《Journal of nanoparticle research》2007,9(4):611-619
Liquid Phase Photo-Deposition (LPPD) technique has been used to obtain both colloidal particles and thin films of metallic
and chloride nickel from solutions of only precursor Ni(acac)2 (acac=2,4-pentandionato). Metallic nickel was obtained from ethanol solutions by direct nickel(II) photoreduction at 254 nm
and by acetone sensitised reaction at 300 nm. In this latter process the rate was higher than in the first one. NiCl2 was formed from CCl4 solution by a solvent-initiated reaction. TEM analysis, performed on colloidal particles of nickel, showed that their dimensions
are in the range 2–4 nm. The films did not present carbon contamination and were characterized by AFM, XPS and GIXRD. Metallic
films consisted of particles of 20–40 nm that are the result of the aggregation of smaller crystallites (4–5 nm). Larger agglomerations
(around 200 nm) have been observed for NiCl2 films. 相似文献
998.
J. Bansmann A. Kleibert F. Bulut M. Getzlaff P. Imperia C. Boeglin K.-H. Meiwes-Broer 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,45(3):521-528
Mass-filtered cobalt clusters with a size of 8 nm have been deposited in-situ under soft-landing conditions onto Au(111).
The spin and orbital moments of the Co nanoparticles on a Au (111) single crystal have been investigated as a function of
the temperature using the element-specific method of X-ray magnetic circular dichroism in photoabsorption. The results hint
at an temperature-dependent spin-reorientation transition which is discussed with respect to different contribution to the
magnetic anisotropy. Furthermore, by means of an in-situ oxidation experiment, the influence of an exposure to oxygen on the
properties of the cobalt clusters has been investigated. 相似文献
999.
Elayaraja Muthuswamy S. Sree Ramadevi H.N. Vasan Cécile Garcia Laure Noé Marc Verelst 《Journal of nanoparticle research》2007,9(4):561-567
A novel synthesis of inorganic–organic hybrid films containing well dispersed and almost uniform size Ag nanoparticles in
agar-agar matrix has been reported. The films are found to be highly stable for more than a year. The colloidal particles
of Ag can be obtained in large quantities in the form of a film or in the gel form when dispersed in agar-agar or by dissolving
in a suitable solvent as solution. Characterization has been done by UV–visible spectroscopy and TEM. The hybrid may be of
interest to study third-order non-linear susceptibility. 相似文献
1000.
We investigate the effect of system properties and adsorption sequence on competitive adsorption of poly(methyl methacrylate) (PMMA) and polystyrene (PS) on narrowly polydispersed cobalt (Co) nanoparticles (D ∼ 27 nm). The adsorbed layer composition is studied using thermo-gravimetric analysis (TGA). We find that adsorbed layers of PS are completely displaced by PMMA when the solvent is a common good solvent. An adsorbed layer of only PMMA is also obtained through competitive adsorption from a common good solvent. However, in a selective solvent that is poor for PS, sequential adsorption leads to the formation of mixed layers. 相似文献