共查询到20条相似文献,搜索用时 15 毫秒
1.
N. Yu. Svechnikov V. G. Stankevich B. N. Kolbasov Y. V. Zubavichus A. A. Veligzhanin V. A. Somenkov L. P. Sukhanov A. M. Lebedev K. A. Menshikov 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2017,11(6):1208-1215
Structure of smooth hydrocarbon CD x films with a high deuterium ratio x ~ 0.5 redeposited from T-10 tokamak D-plasma discharges (NRC Kurchatov Institute, Moscow) has been studied. For the first time, small and wide angle X-ray scattering technique using synchrotron radiation and neutron diffraction have been employed. A fractal structure of CD x films is found to consist of mass-fractals with rough border, surface fractals (with rough surface), plane scatterers and linear chains forming a branched and highly cross-linked 3D carbon network. The found fractals, including sp2 clusters, are of typical size ~1.60 nm. They include a C13 fragment consisting of three interconnected aromatic rings forming a minimal fractal sp2 aggregate 9 × C13. These graphene-like sp2 clusters are interconnected and form a 3D lattice which can be alternatively interpreted as a highly defective graphene layer with a large concentration of vacancies. The unsaturated chemical bonds are filled with D, H atoms, linear sp2 C=C, C=O, and sp3 structural elements like C-C, C-H(D), C-D2,3, C-O, O-H, COOH, C x D(H) y found earlier from the infrared spectra of CD x films, which are binding linear elements of a carbon network. The amorphous structure of CD x films has been confirmed by the results of earlier fractal structure modeling, as well as by researches with X-ray photoelectron spectroscopy which allow finding a definite similarity with the electron structure of their model analogues — polymeric a-C:H and a-C:D films with a disordered carbon network consisting of atoms in sp3 + sp2 states. 相似文献
2.
The optical properties of GeO x film and GeO x /SiO2 multilayer heterostructures (with thickness of GeO x layers down to 1 nm) were studied with the use of Raman scattering and infrared spectroscopy, ellipsometry and photoluminescence spectroscopy including temperature dependence of photoluminescence. The observed photoluminescence is related to defect (dangling bonds) in GeO x and interface defects for the case of GeO x /SiO2 multilayer heterostructures. From analysis of temperature dependence of photoluminescence intensity, it was found that rate of nonradiative transitions in GeO x film has Berthelot type, but anomalous deviations from Berthelot type temperature dependence were observed in temperature dependences of photoluminescence intensities for GeO x /SiO2 multilayer heterostructures. 相似文献
3.
I. D. Lobov M. M. Kirillova L. N. Romashev M. A. Milyaev V. V. Ustinov 《Physics of the Solid State》2009,51(12):2480-2485
The magnetorefractive effect in Fe(t x , Å)/Cr(10 Å) samples grown by molecular-beam epitaxy with a variable thickness of the iron layer (superlattices, cluster-layered nanostructures) has been studied in the IR region (λ = 2–13 µm) in s and p polarizations of light. The magnetoresistive effect in a dc magnetic field, H ≤ 32 kOe, has been measured on the same samples. The iron layer thickness required for the magnetorefractive response to appear has been found to be t Fe ≥ 3 Å. The correlation between the magnitude of the magnetorefractive effect in the mid-IR region and magnetoresistance has been discussed. 相似文献
4.
R. Khordad 《The European Physical Journal B - Condensed Matter and Complex Systems》2010,78(3):399-403
In this work, the diamagnetic susceptibility and the bindingenergy of a hydrogenic donor impurity both in the parabolic andnon-parabolic conduction band models have been calculated withinthe effective mass approximation for a V-grooveGaAs/Ga1- x Al x As quantum wire. According to the resultsobtained from the present work reveals that (i) the value ofdiamagnetic susceptibility due to the non-parabolicity effect ishigher than that of parabolicity effect; (ii) the values ofdiamagnetic susceptibility and binding energy due to thenon-parabolicity effect is not appreciable at low Al molefractions; (iii) the diamagnetic susceptibility approaches to thebulk value both in L \(\rightarrow\) 0 or L \(\rightarrow\) ∞; (iv)the effect of non-parabolocity is not appreciable in the bindingenergy and energy dependent effective mass, for energies lowerthan 50 MeV. 相似文献
5.
The hierarchical structure of fermion masses of the Standard Model is explained in split fermion models by localizing the
fermions at different points in an extra dimension. We consider split fermion models with two bulk scalars compactified on an orbifold. In the static case we find analytical expression for the localizer. We also address the issue of stability of the localizer.
We also find exact solutions for the fermion zero modes. We explore the parameter space of the model. We find ample opportunity
for construction of phenomenologically viable theories exist. 相似文献
6.
I. R. Shein 《Physics of the Solid State》2018,60(10):2012-2018
The energies of formation of vacancies in the carbon and silicon sublattices, the independent elastic constants, the all-round compression, shear and Young’s moduli, and the anisotropy coefficients are determined for the complete and nonstoichiometric cubic phases of 3C-SixCy (x, y = 1.0–0.75) by ab initio methods of the band theory. In the formalism of the density functional perturbation theory (DFPT), the phonon dispersion dependences are obtained for these phases (the comparison with the experiment is given for the complete phase). It is shown that the mechanical characteristics of the phases become strongly anisotropic upon the transition from 3C-SiC0.875 to 3C-SiC0.75. It is established from the analysis of the phonon dispersion curves that the 3C-SiC0.875 and 3C-SiC0.75 phases, in contrast to the complete 3C-SiC phase, are dynamically unstable at T = 0 K. 相似文献
7.
8.
J. P. Guedes S. Azevedo M. Machado 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,80(1):127-135
We have studied, through ab initio calculations, the stability of 60° and 120° boron nitride nanocones containing mono and
multiple boron, nitrogen, and
carbon vacancies. The stability of the vacancies as well as the structures reconstruction mechanism have been investigated.
Our results indicate that the
stability of the cones presenting such vacancies strongly depends on growth conditions. We have also found that multiple vacancies
display formation energies that
are comparable, and in some cases, even lower to the ones presented by monovacancies. Therefore, our results allow us to conclude
that the formation energy does not
depend on the vacancy size. Finally, for 120° cones, we can verify that the stability of the boron and nitrogen vacancies
depends on the position where the atom has
been removed. 相似文献
9.
Based on ab initio quantum calculations of the electronic structure for different conformers of V and V
x
gases, we propose an assignment of the fundamental vibrational states of the compounds. 相似文献
10.
V. V. Mesilov V. R. Galakhov A. S. Semenova D. G. Kellerman L. V. Elokhina 《Physics of the Solid State》2011,53(2):271-275
The electronic structure and specific features of the structure of nonstoichiometric cobaltite Li
x
Na
y
CoO2 (x = 0.42, y = 0.36) have been studied comprehensively. The calculated multiplet for the lowspin state of the Co3+ ion agrees with the experimental spectra. It has been established using X-ray absorption spectra measured in the total photoelectric
effect yield and total fluorescence yield modes that the Li
x
Na
y
CoO2 cobaltite is stoichiometric with respect to the alkali metal near its surface and is defective inside. It has been demonstrated
that the charge compensation in the case of an alkali metal deficit in LixNayCoO2 is due to holes in O 2p states. 相似文献
11.
LSDA + U + SO calculations of the electronic structure of helicoidal Fe1 - xCo x Si ferromagnets within the virtual crystal approximation have been supplemented with the consideration of the Dzyaloshinski-Moriya interaction and ferromagnetic fluctuations of the spin density of collective d electrons with the Hubbard interactions at Fe and Co atoms randomly distributed over sites. The magnetic-state equation in the developed model describes helicoidal ferromagnetism and its disappearance accompanied by the occurrence of a maximum of uniform magnetic susceptibility at temperature T C and chiral fluctuations of the local magnetization at T > T C . The reasons why the magnetic contribution to the specific heat at the magnetic phase transition changes monotonically and the volume coefficient of thermal expansion (VCTE) at low temperatures is negative and has a wide minimum near T C have been investigated. It is shown that the VCTE changes sign when passing to the paramagnetic state (at temperature T S ). 相似文献
12.
Thin films of CdSxTe1-x were deposited by the pulse electrodeposition technique using cadmium sulfate, sodium thiosulfate, and tellurium dioxide
on titanium and conducting glass substrates. Structural studies indicated the formation of polycrystalline films possessing
hexagonal structure. The resistivity varies from 53 Ω cm to 8 Ω cm as the stochiometric coefficient “x” value decreases from 1 to 0. The carrier concentration increases with CdTe concentration. It is observed that as the post-heat
treatment temperature increases, the photosensitivity also increases. It is observed that a post-heat treatment temperature
of 550 °C results in high photosensitivity as well as low light resistance. The optical constants, refractive index (n) and extinction coefficient (k) were evaluated from the transmission spectra of the films of different composition. 相似文献
13.
D. Mourad G. Czycholl 《The European Physical Journal B - Condensed Matter and Complex Systems》2010,78(4):497-507
Zero-dimensional nanocrystals, as obtained by chemical synthesis, offer a broad range of applications, as their spectrum and
thus their excitation gap can be tailored by variation of their size. Additionally, nanocrystals of the type A
x
B1-
x
C can be realized by alloying of two pure compound semiconductor materials AC and BC, which allows for a continuous tuning
of their absorption and emission spectrum with the concentration x. We use the single-particle energies and wave functions calculated
from a multiband sp
3 empirical tight-binding model in combination with the configuration
interaction scheme to calculate the optical properties of
Cd
x
Zn1-
x
Se nanocrystals with a spherical shape. In contrast to common mean-field approaches like the virtual crystal approximation
(VCA), we treat the disorder on a microscopic level by taking into account a finite number of realizations for each size and
concentration.
We then compare the results for the optical properties with recent experimental data and calculate the optical bowing coefficient
for further sizes. 相似文献
14.
M. van Leeuwen 《The European Physical Journal C - Particles and Fields》2009,61(4):569-574
We present selected recent results of multi-hadron correlation measurements in azimuth and pseudorapidity at intermediate
and high p
T
in Au+Au collisions at
, from the STAR experiment at RHIC. At intermediate p
T
, measurements are presented that attempt to determine the origin of the associated near-side (small Δφ) yield at large pseudo-rapidity difference Δη that is found to be present in heavy ion collisions. In addition, results are reported on new multi-hadron correlation measures
at high-p
T
that use di-hadron triggers and multi-hadron cluster triggers with the goal to constrain the underlying jet kinematics better
than in the existing measurements of inclusive spectra and di-hadron correlations. 相似文献
15.
16.
A. N. Romannikov 《Journal of Experimental and Theoretical Physics》2009,108(2):340-348
Electric field E r transverse to the current in a moving quasi-neutral plasma can (and should) be considered using Poisson equations and densities of volume charges emerging in the plasma. In the general case, E r becomes nonlocal; i.e., remote volume charge densities are not screened but affect the formation of E r at the points under investigation. This approach is used for describing a phenomenological theory of radial electric field E r (r) and velocity of toroidal rotation of the plasma in the tokamak. Examples of application of this theory to actual experiments are considered. 相似文献
17.
18.
This paper reports on the results of theoretical investigations carried out for the hydrides Mg2FeH6 and Mg2CoH5 and the mixed hydride Mg2(FeH6)0.5(CoH5)0.5 in terms of the full-potential linearized augmented plane wave (FLAPW) method. It has been shown that the partial substitution of the Co atoms for the Fe atoms leads to a slight increase in the stability of the hydride, but, at the same time, makes it impossible to increase the stability of the alloy. The high stability of the hydrides under investigation has been explained by the strong bonding between atoms of the transition metal and hydrogen. 相似文献
19.
We use an appropriate combination of moments of finite energy sum rules in QCD in order to compute the B
q
-meson decay constants f
B
and
. We perform the calculation using a two-loop computation of the imaginary part of the pseudoscalar two point function in terms of the running bottom quark mass. The results are stable against the so-called QCD duality threshold, and they are in agreement with the estimates obtained from Borel transform QCD sum rules and lattice computations.Received: 28 July 2004, Revised: 10 September 2004, Published online: 23 November 2004PACS:
12.38.Bx, 12.38.LgSupported by MCYT-FEDER under contract FPA2002-00612. 相似文献
20.
From a macroscopic theory of the quantum vacuum in terms of conserved relativistic charges (generically denoted by q
(a) with label a), we have obtained, in the low-energy limit, a particular type of f(R) model relevant to cosmology. The macroscopic quantum-vacuum theory allows us to distinguish between different phenomenological
f(R) models on physical grounds.
The text was submitted by the authors in English. 相似文献