共查询到20条相似文献,搜索用时 31 毫秒
1.
L. Henrard A. Loiseau C. Journet P. Bernier 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,13(4):661-669
Determining precisely the atomic structure of single-wall carbon nanotubes is essential since it tailors electronic properties
of this new carbon material. Here, we present a quantitative electron diffraction study of electric-arc produced single-wall
carbon nanotube bundles, combined with simulations based on the kinematic theory and with real-space images. We stress the
importance of the twist of the bundle in the interpretation of our data and we analyze both packing lattice parameters and
chirality distribution. We show that, within a given bundle, no chirality is favoured whereas SWNT diameters are almost uniform.
Received 5 February 1999 相似文献
2.
D. Zanghi A. Traverse J.-P. Dallas E. Snoeck 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,12(1):171-179
Ni ions were implanted in bulk AlN with the goal to form embedded metallic clusters. Combining several characterisation techniques
such as X-ray absorption spectroscopy, X-ray diffraction and high resolution transmission electron microscopy, we determined
the lattice parameter of the Ni clusters that display a fcc crystalline structure. The average size increases when the ion
fluence is increased or after a thermal treatment. Thanks to moiré fringes observed by high resolution transmission electron
microscopy and to satellite peaks seen on the diffraction patterns, we concluded that the annealed Ni clusters orientate their
(002) planes on the (101) of AlN. Moreover, the satellite positions allowed us to calculate Ni cluster average diameters,
that are in agreement with average sizes deduced by X-ray absorption spectroscopy.
Received 25 August 1999 and Received in final form 8 February 2000 相似文献
3.
V. Milosavljević S. Djeniže 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(3):385-390
On the basis of the precisely recorded 706.52 nm He I line shape we have obtained the basic plasma parameters i.e. electron temperature (T) and electron density (N) using our new line deconvolution procedure in the case of five various plasmas created in a linear, low-pressure, pulsed
arc discharge. Plasma parameters have been also measured using independent experimental diagnostical techniques. Excellent
agreement was found among the two sets of the obtained parameters. This enables our deconvolution procedure to recommendation
for plasma diagnostical purposes, especially in astrophysics where direct measurements of the plasma parameters (T and N) are not possible. Besides, on the basis of the observed asymmetry of the Stark broadened line profile we have obtained its
ion broadening parameter (A) caused by influence of the ion microfield to the line broadening mechanism and also the influence of the ion dynamic effect
(D) to the line shape. Our A and D parameters represent the first data obtained experimentally using the line profile deconvolution procedure. We have found
stronger influence of the ion contribution to the 706.52 nm He I line profile than the existing theoretical approximations
estimate. This can be important for plasma modeling or for diagnostics.
Received 30 October 2002 Published online 15 April 2003
RID="a"
ID="a"e-mail: vladimir@ff.bg.ac.yu 相似文献
4.
K. Wang P. Donnadieu P. Garoche 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,13(2):279-287
We report on grain growth and related structure change in single phased Al-Li-Cu quasicrystals. The icosahedral phase grains
have been investigated using scanning ion microscopy and transmission electron microscopy. Regular boundaries between large
grains have been observed both before and after high temperature annealing. The electron diffraction study shows that the
grain growth is accompanied by a reduction of the phason-strains. The orientation relation between grains sets the 2-fold
icosahedral axes parallel, and the coincidence of the planes depends on the phason strain-field. The effect of phason-strain
field on these boundaries is discussed. It is proposed that the phason strain elimination can play a role in the grain growth.
Received 1 February 1999 and Received in final form 12 May 1999 相似文献
5.
The branched crystal morphology of linear polyethylene formed at various temperatures from thin films has been studied by
atomic-force microscopy (AFM), transmission electron microscopy (TEM), electron diffraction (ED) pattern and polymer decoration
technique. Two types of branched patterns, i.e. dendrite and seaweed patterns, have been visualized. The fractal dimension d
f = 1.65 of both dendrite and some of seaweed patterns was obtained by using the box-counting method, although most of the
seaweed patterns are compact. Selected-area ED patterns indicate that the fold stems tilt about 34.5° around the b-axis and polymer decoration patterns show that the chain folding direction and regularity in two (200) regions are quite
different from each other. Because of chain tilting, branched crystals show three striking features: 1) the lamella-like branches
show two (200) regions with different thickness; 2) the crystals usually bend towards the thin region; 3) the thick region
grows faster by developing branches, thus branches usually occur outside the thick region. The branched patterns show a characteristic
width w, which gives a linear relationship with the crystallization temperature on a semilogarithmic plot.
Received 15 March 2002 and Received in final form 29 April 2002 相似文献
6.
V. Dureuil C. Ricolleau M. Gandais C. Grigis 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,14(1):83-88
The crystalline structure of Co clusters embedded in an amorphous Al2O3 matrix was studied by transmission electron microscopy (TEM) and electron diffraction (TED). In the first stage of the growth
a metastable structure (body-centred-cubic) is observed. A face-centred-cubic phase (fcc) is found when the size of the clusters
increases ( diameter > 4 nm). The hexagonal-close-packed phase arises in the fcc phase by a succession of stacking faults at the largest sizes.
The mechanisms of phase transformation have been determined by using high resolution electron microscopy (HREM). The chemical
nature of the clusters, in particular the existence of Co-O bonds, was investigated by using electron energy loss spectroscopy
(EELS).
Received 03 July 2000 and Received in final form 22 December 2000 相似文献
7.
The effect of oxidation on the structure of nickel nanoparticles 总被引:1,自引:0,他引:1
B. Rellinghaus S. Stappert E.F. Wassermann H. Sauer B. Spliethoff 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):249-252
The structural properties of nickel nanoparticles which are prepared by means of DC sputtering in argon and subsequently oxidized
in ambient air are reported. Ex situ structural and chemical investigations utilizing (high resolution) transmission electron microscopy and electron energy loss
spectroscopy reveal that the particles consist of a metallic core surrounded by an oxide shell. The lattice constant of the
nickel core is found to increase significantly with decreasing particle size. This widening of the nickel lattice is attributed
to an interfacial stress that originates from the lattice mismatch between nickel and nickel oxide.
Received 21 December 2000 相似文献
8.
M. Angeloni C. Aruta G. Balestrino P. Orgiani A. Tebano P.G. Medaglia 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(4):561-566
In this report we demonstrate that high quality epitaxial heterostructures, based on metallic SrRuO3 and insulating SrTiO3 individual blocks a few unit cells thick, can be grown in a purely 2D, layer-by-layer mode, using pulsed laser deposition
with in situ reflection high energy electron diffraction (RHEED) diagnostics. The thickness of each constituent block can be controlled
at the level of a single unit cell. A detailed investigation carried out at the synchrotron facility, ESRF, by various X-ray
techniques has demonstrated that each intensity oscillation of the RHEED specular spot corresponds strictly to the growth
of a single perovskite unit cell, either SrRuO3 or SrTiO3. Furthermore, we show that, in these structures, the interfaces between the different constituent blocks are very sharp with
a roughness of only one unit cell.
Received 3 July 2002 / Received in final form 12 September 2002 Published online 31 October 2002
RID="a"
ID="a"e-mail: tebano@uniroma2.it 相似文献
9.
R.-P. Methling V. Senz E.-D. Klinkenberg Th. Diederich J. Tiggesbäumker G. Holzhüter J. Bansmann K.H. Meiwes-Broer 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):173-176
We have investigated the magnetic properties of mass-selected iron clusters using the Magneto-Optical Kerr effect (MOKE) in
longitudinal geometry. For the production of these clusters, a newly developed continuous arc cluster ion source (ACIS) was
applied. The source is based on cathodic arc erosion in inert gas environment and subsequent expansion into high vacuum. Its
intensity and stability allows mass selection within a wide size range. The source efficiency is demonstrated in deposition
experiments and transmission electron microscopy. For mass-selected iron particles deposited into a silver matrix we could
observe a change in the magnetic behaviour from ferromagnetism to superparamagnetism around a size of 10 nm at room temperature.
Received 1st December 2000 相似文献
10.
S. Djeniže A. Srećković S. Bukvić 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(1):11-16
We have obtained transition probabilities (Einstein's A values) of thirteen transitions in doubly (N III), six in triply (N IV) and two in four times (N V) ionized nitrogen spectra
belonging to the 3s-3p and 3p-3d transitions using a relative line intensity ratio (RLIR) technique. The linear low-pressure pulsed arc was used as an optically
thin plasma source operated at 51 400 K electron temperature and 2.2×1023 m-3 electron density in nitrogen plasma. Our A values are compared to recent theoretical and experimental data.
Received 18 December 2001 / Received in final form 29 January 2002 Published online 28 June 2002 相似文献
11.
M. Dubiel S. Brunsch W. Seifert H. Hofmeister G.L. Tan 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):229-232
Ag particles of 3.9 and 5.1 nm mean size in silicate glasses were produced by ion exchange and subsequent annealing at 480
and 600 °C. These thermal treatments may induce stresses in matrix and particles in addition to the well known effect of surface atoms
because of the thermal expansion mismatch of both materials. Structural characterisation of the particles by high-resolution
electron microscopy revealed a size-dependent lattice dilatation quite opposite to the so far observed lattice contraction
of similar metal/glass composites. This result, confirmed by X-ray absorption spectroscopy at the Ag K-edge, is discussed
in terms of an Ag-Ag bond length increase near the particle surface. The temperature-dependent EXAFS spectra (10-300 K) indicate
an increased thermal expansion coefficient of the particles with an increased mean particle size calculated on the basis of
an anharmonic Einstein model. With that the bond length increase can be explained. The results can be interpreted by a combination
of both the particle size effects and the influence of the surrounding matrix.
Received 30 November 2000 相似文献
12.
Interplay of charge, spin, orbital and lattice correlations in colossal magnetoresistance manganites
A. Weiße H. Fehske 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,30(4):487-494
We derive a realistic microscopic model for doped colossal magnetoresistance manganites, which includes the dynamics of charge,
spin, orbital and lattice degrees of freedom on a quantum mechanical level. The model respects the SU(2) spin symmetry and the full multiplet structure of the manganese ions within the cubic lattice. Concentrating on the hole
doped domain ( 0≤x≤0.5) we study the influence of the electron-lattice interaction on spin and orbital correlations by means of exact diagonalisation
techniques. We find that the lattice can cause a considerable suppression of the coupling between spin and orbital degrees
of freedom and show how changes in the magnetic correlations are reflected in dynamic phonon correlations. In addition, our
calculation gives detailed insights into orbital correlations and demonstrates the possibility of complex orbital states.
Received 4 September 2002 / Received in final form 8 November 2002 Published online 31 December 2002 相似文献
13.
Importance of lattice contraction in surface plasmon resonance shift for free and embedded silver particles 总被引:3,自引:0,他引:3
W. Cai H. Hofmeister M. Dubiel 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,13(2):245-253
The size evolution of the surface plasmon resonance was investigated for free and embedded silver particles between about
2 to 10 nm in size. The crystal lattice of such particles as analyzed by high resolution electron microscopy show linear contraction
with reciprocal particle size. Based on this, a model was presented by combining the lattice contraction of particles and
the free path effect of electrons to predict the size evolution of the resonance. The results reveal a contribution of the
lattice contraction to the resonance shift according to a roughly linear relation that changes slightly with particle radius
(> 1.0 nm) and surrounding media. This surface plasmon resonance shift proceeds linearly with reciprocal size for Ag particles
in vacuum and argon, but for Ag particles embedded in glass it appears to be independent of the radius down to nearly 1 nm.
All predictions are quantitatively compared to previously reported experimental data and a good agreement is obtained. An
unusual red-shift observed for Ag particles in glass may be attributed to a thermal expansion mismatch induced lattice dilatation.
Received 26 July 2000 and Received in final form 14 September 2000 相似文献
14.
H. Kuzmany W. Plank M. Hulman Ch. Kramberger A. Grüneis Th. Pichler H. Peterlik H. Kataura Y. Achiba 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,22(3):307-320
We report on the evaluation of the distribution of diameters for nanotube samples with a wide variation of mean diameters.
Such results were obtained from a detailed analysis of the radial breathing mode Raman response and compared to results obtained
from an evaluation of optical spectra and X-ray diffraction pattern. The evaluation of the Raman data needs a well refined
analysis as the experimental analysis exhibits a rather complicated and oscillating relation between response and exciting
laser. Both, an exact calculation where the density of states was considered explicitly and an approximate calculation were
applied. Both models used for the analysis are able to explain several unexpected results from the experiment such as the
oscillating behavior of the spectral moments, unusual discontinuities in the first moments of the Raman response for excitation
in the IR, a fine structure for the response in optics and Raman, and an up shift of the RBM frequency as compared to qualified
ab initio calculations. In detail the first moment and the variance of the spectra were used for the evaluation of the diameter distribution.
To obtain good results between experimental and theoretical oscillation pattern the transition energy between the first two
van Hove singularities had to be scaled up which is considered as a result from coulomb interaction of the electrons in the
tubular material. On the other hand the analysis does not only allow to determine the mean value and the width of the diameter
distribution but yields also a value for the average bundle diameters or, alternatively, the strength of the tube-tube interaction.
The model used for the analysis of the Raman data is also appropriate to analyze the optical response, at least for the spectral
range from 0.5 eV to 3.5 eV. The fine structure in the response for the transitions between the three lowest van Hove singularities
is well reproduced and the mean tube diameters and their distribution is obtained in very good agreement with the results
from the Raman analysis. From the X-ray analysis the same mean values and comparable distributions for the tube diameters
were received whereas the bundle diameters could not be retained with high precision in this case.
Received 18 February 2001 and Received in final form 3 April 2001 相似文献
15.
V. Milosavljević S. Djeniže 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,15(1):99-104
Characteristics of the Stark broadened and overlapping 447.1 nm He I spectral line and its forbidden 447.0 nm components have
been measured at electron densities between 4.4×1022 m-3 and 8.2×1022 m-3 and electron temperatures between 18 000 K and 33 000 K in plasmas created in five various discharge conditions using the
low pressure pulsed arc as an optically thin plasma source operated in helium-nitrogen-oxygen gas mixture. Good agreement
was found among our measured line characteristics and their existing calculated values, based on the quasistatic approximation.
Possible influence of the singly ionized oxygen impurity atoms (O II) on the intensity values of the dip between allowed and
forbidden components was found that can explain the disagreement among some existing experimental and calculated line characteristics
data, at higher electron temperatures and densities. On the basis of the observed asymmetry of the 447.1 nm spectral line
profile we have obtained the ion contribution parameter at 1022 m-3 electron density and 8 000 K electron temperature.
Received 20 February 2001 and Received in final form 25 April 2001 相似文献
16.
A. Michel V. Pierron-Bohnes J.P. Jay P. Panissod S. Lefebvre M. Bessière H.E. Fischer G. Van Tendeloo 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,19(2):225-239
Epitaxial Co/Mn multilayers (0.75 to 6 nm Co, 0.4 nm Mn layer thickness) have been grown on mica substrates covered by a (0002)
Ru buffer layer. The structural properties of these layers have been studied using X-ray diffraction, nuclear magnetic resonance
(NMR), and high resolution transmission electron microscopy (HRTEM). The Co layers, grown as face centred cubic (fcc), were
found to be stabilised by the very thin Mn layers. Data obtained using X-ray diffraction and NMR were analysed and found to
be in good agreement, while Monte-Carlo simulations were used to interpret the data and calculate the expected diffracted
intensity and NMR spectra. The HRTEM data show that the Mn layers give rise to a large strain contrast extending, in the growth
direction, over a distance which exceeds the thickness of the Mn layers. The superlattices could be described as having an
fcc structure containing randomly located stacking faults with varying densities. The results verify the presence of a dominant,
almost perfect phase of fcc stacking, and of a faulted hcp phase, while the number of defects increases with the Co layer
thickness.
Received 27 October 1999 and Received in final form 29 May 2000 相似文献
17.
B.I. Ostrovskii D. Sentenac I.I. Samoilenko W.H. de Jeu 《The European physical journal. E, Soft matter》2001,6(4):287-294
We report on the thin-film behaviour of a polyacrylate with phenyl benzoate mesogenic side groups and a narrow polydispersity.
Depending on the degree of polymerisation, these polymers show a nematic, a smectic-A d, a re-entrant nematic and a C phase with a two-dimensional monoclinic lattice. X-ray reflectivity and atomic-force microscopy
have been used to characterize the structure and surface morphology. The system exhibits two stable side-chain packing configurations
with incommensurate spacings that can be both stabilized at a free surface. Thin films in the nematic phase show a structural
dewetting induced by the growth of surface domains of the C phase. Additionally, surface-induced ripples with a nanoscale
lateral period form at the air-film interface. We attribute these patterns to a coupling between the local liquid crystalline
ordering of the mesogenic side groups and the surface curvature energy.
Received 28 February 2001 and Received in final form 6 August 2001 相似文献
18.
B. Viaris de Lesegno J.C. Karam M. Boustimi F. Perales C. Mainos J. Reinhardt J. Baudon V. Bocvarski D. Grancharova F. Pereira Dos Santos T. Durt H. Haberland J. Robert 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(1):25-34
A new Stern Gerlach interferometer operating with a nozzle beam of metastable argon atoms Ar* (3p5 4s, 3
P
2) is described. The selection of incoming (polarisation) and outgoing (analysis) Zeeman sublevels is achieved by use of laser
induced transitions at two wavelengths, 811.5 nm (closed J = 2 → J = 3 transition) and 801.5 nm (open J = 2 → J = 2 transition). Linear superpositions of Zeeman sublevels, just beyond the polariser and just before the analyser, are prepared
by means of two zones where Majorana transitions take place. In between, a controlled magnetic field configuration (the phase
object) is produced within a triple μ-metal shielding. Standard interference patterns are obtained by scanning the field and
detecting the atoms by secondary electron emission from a Faraday cup. When a static radial magnetic gradient is used, the
beam profile is modulated by interference. The transverse pattern, which can be translated at will by adding a homogeneous
field, is observed for the first time using a multi-channel electron multiplier followed by a phosphor screen and a CCD camera.
The results satisfactorily agree with all theoretical predictions.
Received 27 June 2002 / Received in final form 20 September 2002 Published online 4 February 2003
RID="a"
ID="a"e-mail: perales@lpl.univ-paris13.fr
RID="b"
ID="b"UMR 7538 du CNRS 相似文献
19.
A. Vecchione M. Gombos S. Pace L. Marchese G. Cerrato C. Tedesco P.W. Stephens C. Noce 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,26(1):51-55
We report the preparation and the structural and morphological characterization of the perovskite compound NdSr2RuCu2Oy. The crystal structure of this material has been determined by a combined high-resolution electron microscopy, selected area
electron diffraction and high-resolution X-ray powder diffraction study. The morphology of the samples has been monitored
by a scanning electron microscope equipped with an energy dispersive spectrometer attachment by which the microanalysis of
the crystallites has been also performed. Finally, dc magnetic susceptibility measurements show that this compound behaves
like an enhanced paramagnetic metal with evidence of neither magnetic order and neither superconducting one.
Received 15 November 2001 相似文献
20.
Ya.E. Krasik A. Dunaevsky J. Felsteiner 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,15(3):345-348
We studied the emission properties of carbon fiber cathodes. These cathodes were made either of a single carbon fiber or of
carbon fabric, or of an array of carbon fiber bundles. It was found that an intense emission of electrons occurs from a plasma
which is formed on the carbon fiber surface as a result of a flashover process. In addition, the time delay in the appearance
of the electron emission with respect to the start of the accelerating voltage pulse was found to depend strongly on the voltage
growth rate. A simple model of the plasma formation is suggested.
Received 12 March 2001 相似文献