共查询到20条相似文献,搜索用时 31 毫秒
1.
Lutful Bari Bhuiyan 《Molecular physics》2013,111(15):1863-1871
A generalised form of a local contact condition for the charge profile in a primitive model planar double layer [Bhuiyan, Outhwaite, and Henderson, Mol. Phys. 107, 343 (2009)] at low electrode charge is examined for completely asymmetric, binary electrolytes. The cation and anion sizes are taken to be different from each other with the valencies being 2+:1? or 1+:2?, while the electrode surface charge density is varied from being negative through zero to being positive. Monte Carlo simulation data obtained for such double layer systems at varying ionic radius ratios and electrolyte concentrations suggest the generalised contact relation to be valid at low charge on the electrode. 相似文献
2.
N. A. Inogamov Yu. V. Petrov S. I. Anisimov A. M. Oparin N. V. Shaposhnikov D. von der Linde J. Meyer-ter-Vehn 《JETP Letters》1999,69(4):310-316
Recent experiments have utilizied high-power subpicosecond laser pulses to effect the ultrafast heating of a condensed material
to temperatures far above the critical temperature. Using optical diagnostics it was established that a complicated density
profile with sharp gradients, differing substantially from an ordinary rarefaction wave, forms in the expanding heated matter.
The present letter is devoted to the analysis of the expansion of matter under the conditions of the experiments reported
by D. von der Linde, K. Sokolowski-Tinten, and J. Bialkowski, Appl. Surf. Science 109/110, 1 (1996); K. Sokolowski-Tinten, J. Bialkowski, A. Cavalleri et al., Proc. Soc. Photo-Opt. Instum. Eng. 3343, 46 (1998); and, K. Sokolowski-Tinten, J. Bialkowski, A. Cavalleri et al., Phys. Rev. Lett. 81, 224 (1998). It is shown that if the unloading adiabat passes through the two-phase region, a thin liquid shell filled with
low-density two-phase matter forms in the expanding material. The shell moves with a constant velocity. The velocity in the
two-phase material is a linear function of the coordinate (flow with uniform deformation), and the density is independent
of the coordinate and decreases with time as t
−1.
Pis’ma Zh. éksp. Teor. Fiz. 69, No. 4, 284–289 (25 February 1999) 相似文献
3.
Abtract One of the simplest examples of possible application of the μSR
2 method for estimating the sizes of diamagnetic domains is analyzed in detail. The domains have been observed for the first
time by means of the μ SR method in beryllium [G. Solt, C. Baines, V. S. Egorov et al., Hyperfine Interactions 104, 257 (1997)]. Results are given from a computer simulation of a μSR
2 experiment to measure domain sizes in Be. An algorithm is described for processing the experimental results. It is graphically
demonstrated that domain sizes can be estimated within the accelerator operating time allocated for an ordinary μSR experiment.
Zh. éksp. Teor. Fiz. 115, 2133–2142 (June 1999) 相似文献
4.
Abstract Compounds with high fluorinating capacity are obtained when rubidium and cesium chlorides are fluorinated in a stream of elemental fluorine. Best results are obtained when the, temperature is kept in the range of 140–170°C. These products were first assumed to be polyfluorides, MF3, of Rb and Cs 1. It was later assumed by various researchers 2 that the products are really tetrafluorohalates of Rb and Cs, formulated as MC1F4. One of the authors was himself involved in the problem of trying to establish the structure of these products. It is, however, a very difficult problem since pure products giving constant analytical results were not obtained. During the fluorination process, which is an exothermic one, enough heat is evolved to melt the reaction medium and the temperature rises above that needed to decompose the products. It is therefore impossible to obtain reliable analytical data, the products being a mixture of regular fluorides, MF, and the active, fluorinating, ones. No final proof has therefore been found for the C1F? 4 structure. 相似文献
5.
A new allotropic form of amorphous silicon with sp hybridization of the valence electrons is discovered. The new material consists of linear chains of atoms. A small fraction
of the atoms are in the sp
2 state. Acting as bridges, these atoms couple the linear chains into a single random network. This conclusion is based on
an analysis of experimental data on the effect of annealing and ion implantation on the structure of the short-range order
and the properties of amorphous-silicon films obtained by different methods.
Pis’ma Zh. éksp. Teor. Fiz. 67, No. 9, 646–649 (10 May 1998) 相似文献
6.
It is pointed out that in the partial oxidation of porous silicon (PS) formed on heavily doped crystals, the topology of the
pores can result in the formation of an anisotropic material with strings of nanometersized silicon granules embedded in insulating
silicon dioxide SiO2. In this range of granule sizes the correlation effects in the tunneling of electrons (holes) are strong on account of their
Coulomb interaction. This should be manifested as discrete electron and hole tunneling at temperatures comparable to room
temperature. The room-temperature current-voltage characteristics of n
+-PSp
+-p
+ diode structures with a PS interlayer on p
+-Si, which exhibit current steps on the forward and reverse branches, are presented. The current steps are attributed to discrete
hole tunneling along the silicon strings in SiO2.
Pis’ma Zh. éksp. Teor. Fiz. 67, No. 10, 794–797 (25 May 1998) 相似文献
7.
A new parameter is proposed for characterizing boundary friction between solids—the probability Q that some contact spot will be converted to a wear particle as the real contact area shifts by one mean contact-spot diameter.
A method is proposed for the phenomenological detection of optimum regimes of boundary friction, which are characterized by
the minimum wear intensity of the sample material, and for measuring the corresponding quantity Q=Q
opt. For babbitt, one of the most frictionless materials, the value of Q
opt is found to be ≈2×10−10. When data on the linear wear intensity I
h
, the contact pressure p
n
, and the hardness H are available, Q can be calculated for the given test conditions. Deviations of Q from the value Q
opt (for a given material) can serve as a criterion for how closely a prepared surface structure approaches the optimal.
Zh. Tekh. Fiz. 68, 48–52 (April 1998) 相似文献
8.
ABSTRACTInverted perovskite solar cells (PSCs) have attracted much attention due to their low-temperature and solution-based process. Electron transport layers are important components in inverted PSCs. Non-fullerene n-type organic small molecules seem to be more attractive as electron transport layers, because their structures are easy to be synthesised and modified. In this paper, density functional theory and semi-classical Marcus electron transfer theory were used to explore the electron transport properties in three azaacene derivatives, including one experimentally reported molecule, 1,4,9,16-tetrakis((triisopropylsilyl)ethynyl)quinoxalino[2?,3?:4″,5″]cyclopenta[1″,2″,3″:5′,6′]acenaphtho[1′,2′:5,6]pyrazino[2,3-b]phenazine (1), and two theoretically designed molecules (2 and 3). Compound 2 is formed by substituting i-Pr groups in compound 1 with H atoms, which is designed to evaluate the effect of i-Pr groups on the electron transport properties. Compound 3 is designed by adding one more benzopyrazine group to the conjugation structure of compound 1. It shows that i-Pr group can increase HOMO and LUMO energy levels and improve solubility in organic solvent and hydrophobicity. Enlarging conjugation can not only decrease LUMO energy level and electron reorganisation energy, but also can increase solubility and electron mobility. So our designed compound 3 is expected to be a potential electron transport material in inverted PSCs. 相似文献
9.
《光谱学快报》2013,46(5-6):407-418
The complete 1H and 13C NMR assignment and stereochemical elucidation of four norbornene derivatives (1–4) are presented. These derivatives were obtained by an asymmetric Diels–Alder reaction of a chiral dienophile, from D‐glucose, as leukotriene D4 receptor antagonists. NOE measurements of the four products between H‐7b and H‐5 readily allowed discrimination between exo‐ (2, 4) and endo‐ (1, 3) diastereomers with respect to methyl carboxylate and tetrahydrofuro[1,3]dioxolyl groups. Further discrimination and subsequent absolute configuration determination of the two endo‐ and two exo‐ products were performed by NOE peak measurements and molecular modeling calculations of relative interproton distances of the most stable conformations of each isomer. 相似文献
10.
Abstract Lithia water, a community resource of local historical significance, is described as a central theme in the undergraduate analytical chemistry sequence. A statistical comparison of the classical determination of major cations (Na+, K+, Ca2+, Mg2+) and anions (HCO3 ?, Cl?) reinforces statistical and charge‐balance concepts covered in analytical chemistry. Subsequent determination of these major cations by inductively coupled plasma (ICP) enables students to statistically evaluate the presence of bias between instrumental and classical methods. The effect of easily ionized elements on ICP calibration sensitivity and linearity via the use of cesium as an ionization suppressor is reported. 相似文献
11.
Abstract The crystal structure of the title compound, C17H13N5O4, has been determined by single crystal x-ray diffraction at room temperature. The molecule is not planar, with dihedral angles of 7.2(1)° between the quinoline ring and N-methylhydrazone group, and 17.45(2)° between the N-methylhydrazone group and the phenyl ring. The crystal parameters of this compound are as follows: monoclinic P 21/n, a=9.525(2)Å, b = 15.192(2) Å, c = 11.302(2) A, β = 94.722(3)°, V = 1629.8(6) Å3, Z = 4, Dx = 1.432 g/cm3, F(000) = 728, λ (MoKα) = 0.71070 Å, μ = 0.106 mm?1, Rint = 0.017. The structure was solved by SHELXS-86 and refined by SHELXL-93. R = 0.07 for 2438 observed reflections with I > 2σ (I). 相似文献
12.
B. Drossel M.A. Moore 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,21(4):589-594
We study the low-temperature phase of the three-dimensional ±
J Ising spin glass in Migdal-Kadanoff approximation. At zero temperature, T
= 0, the properties of the spin glass result from the ground-state degeneracy and can be elucidated using scaling arguments based
on entropy. The approach to the asymptotic scaling regime is very slow, and the correct exponents are only visible beyond
system sizes around 64. At T
> 0, a crossover from the zero-temperature behaviour to the behaviour expected from the droplet picture occurs at length scales
proportional to T
-2/ds
where ds is the fractal dimension of a domain wall. Canonical droplet behaviour is not visible at any temperature for systems whose
linear dimension is smaller than 16 lattice spacings, because the data are either affected by the zero-temperature behaviour
or the critical point behaviour.
Received 18 February 2001 相似文献
13.
C.Z. Dong S. Fritzsche B. Fricke 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(1):5-13
The 17 levels of the 3
d
10
, 3
d
9
4
s and 3
d
9
4
p configurations, and the electric-dipole transitions among these levels are calculated for the three nickel-like ions Se6+, Y11+ and Sn22+ by using large-scale multiconfiguration Dirac-Fock wavefunctions. From these computations, the excitation energies and transition
probabilities as well as the lifetimes of 3
d
9
4
p levels are derived, including all dominant effects of relativity, correlation and of the rearrangement of the electron density
within the same framework. Comparison is made with the scarce number of experimental data and previous semi-empirical computations. 相似文献
14.
Sema Özturk Şamil Işik Erbil Aguar Selami Şalsmaz H. K. Fun Ahmet Erdönmez 《光谱学快报》2013,46(2):245-254
Abstract The crystal structure of the title compound, C41 H35 N7 O6 S3 was determined as monoclinic by single crystal X-Ray diffraction technique. The molecular structure was identified by IR, 1H-NMR, 13C-NMR and elemental analysis. The crystal parameters of this compound are as follows: monoclinic P 2 1/n, a = 12.694(2) Å, b = 26.204(2) Å, c = 13.005(2) Å, β = 102.95(2)°, V = 4216.02(1) Å.3, Z = 4, Dx = 1.289 g/cm3, F(000) = 1704, λ (MoKα) = 0.71070 Å, μ = 0.2 mm?1. The structure was solved by SHELXS-97 and refined by SHELXL-97. R = 0.06 for 3178 observed reflections with I > 2σ (I). 相似文献
15.
Abstract The change in microstrains ε, block sizes L and in the temperature dependences of conductivity of polysilicon with the grain size 30-40nm at N+, Ne+, P+ ion irradiation has been studied. It is shown that ε increases while L practically is not changing up to amorphization. The change in conductivity is governed by an increase in the density of states near the Fermi level and depends both on the damage rate for the given ions and their chemical activity. 相似文献
16.
A. K. Pikaev A. V. Gogolev V. P. Shilov A. M. Fedoseev 《Isotopes in environmental and health studies》2013,49(10):465-469
The paper is a short review of experimental data obtained during the study of reactivity of ions of actinides towards inorganic free radicals in irradiated aqueous solutions by pulse radiolysis method. The values of rate constants of reactions of these ions with primary products of water radiolysis (eaq ?, H, OH, O?) and secondary radicals formed via reactions of these products with solutes and/or as a result of direct action of ionizing radiation on solutes (SO4 ?, NO3, Cl2 ?, CO3 ?, O2 ? etc.) are listed. The peculiarities of the reactivity are discussed. The examples of application of the obtained data for the simulation of radiolytical transformations of ions of actinides are presented. 相似文献
17.
The thermoluminescence of single crystals of corundum containing anion defects following x-ray and laser excitation is investigated.
Its features in the luminescence bands of F, F+, and Cr3+ centers are studied. Synchronous measurements of the thermoluminescence and thermally stimulated exoelectron emission are
performed by the fractional glow technique following x-ray and laser excitation of the samples. It follows from the results
obtained that several traps are active in the temperature range of the principal dosimetric peak (400–500 K). The spectral
sensitivity curve contains maxima corresponding to absorption bands of F, F+, and Al
i
+
centers. A possible mechanism for the recombination luminescence of F centers is discussed. It is found that the material
exhibits high sensitivity to small doses of ultraviolet laser radiation.
Zh. Tekh. Fiz. 67, 72–76 (July 1997) 相似文献
18.
A general expression for the resonant contribution to a tunneling current has been obtained and analyzed in the tunneling
Hamiltonian approximation. Two types of resonant tunneling structures are considered: structures with a random impurity distribution
and double-barrier structures, where the resonant level results from size quantization. The effect of temperature on the current-voltage
curves of tunneling structures is discussed. The study of the effect of potential barrier profile on the d
2
I/dV
2 line shape is of interest for experiments in inelastic tunneling spectroscopy. Various experimental situations where the
inelastic component of the tunneling current can become comparable to the elastic one are discussed.
Fiz. Tverd. Tela (St. Petersburg) 40, 1151–1155 (June 1998) 相似文献
19.
An x-ray diffraction study of the paraphase of the (PbMg1/3Nb2/3O3)0.6-(PbTiO3)0.4 solid solution has been found to exhibit a clearly pronounced ferroelectric transition. It is shown that Pb2+ ions occupy a special position (000), as opposed to pure PMN and other relaxor ferroelectrics, where they are displaced from
it in random directions. The absence of these displacements indicates suppression of frozen-in random electric fields in this
compound.
Fiz. Tverd. Tela (St. Petersburg) 41, 1282–1285 (July 1999) 相似文献
20.
S. Kumar P. Majumdar 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,50(4):571-579
We suggest and implement a new Monte Carlo strategy for correlated models
involving fermions strongly coupled to classical degrees of freedom, with
accurate handling of quenched disorder as well. Current methods
iteratively diagonalise the
full Hamiltonian for a system of N sites with computation time
τN ∼N4. This limits achievable sizes to N ∼100. In
our method
the energy cost of a Monte Carlo update is computed from
the Hamiltonian of a cluster, of size Nc, constructed around the reference
site, and embedded in the larger system. As MC steps sweep over the system,
the cluster Hamiltonian also moves, being reconstructed at each site where
an update is attempted. In this method
τN,Nc
∼NNc3.
Our results are obviously exact when Nc=N,
and converge quickly to this asymptote with increasing Nc, particularly
in the presence of disorder.
We provide detailed benchmarks
on the Holstein model and the double exchange
model. The `locality' of the energy cost, as evidenced by our results,
suggests that several important but inaccessible problems can now be handled
with control. This method forms the basis of our studies in Europhys. Lett.
68, 564 (2004), Phys. Rev. Lett. 94, 136601 (2005), and
Phys. Rev. Lett. 96, 016602 (2006). 相似文献