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1.
Using the data on dispersion of refractive indices in the visible region, the experimental values of the components L
j
of the Lorentz tensor have been obtained for uniaxial (crystalline, oriented on a substrate, and stretched) films of conjugated
polymers from nanometer to micrometer thicknesses. The dependence of the components L
j
on the axial and planar orientations of macromolecules with respect to the optical axis of the film, technology of fabricating
the films, and chemical structure of macromolecules has been elucidated. The correlation between the components L
j
and the measured parameter η has been determined and the analytical dependence L
j
(η) for films with both types of macromolecular orientation has been established. In the visible region (0 ≤ η ≤ 0.5), the
presence of one point (η = 1/3) of isotropization of the tensor L and three points (η = 0, 1/3, and 0.5) of isotropization of the local field tensor f has been revealed. The point η = 1/3 of isotropization of the tensors L and f has been determined. A comparison has been made between the values of L
j
(η) with predictions of known models of the local field for conjugated polymers. 相似文献
2.
Osamu Yamashita 《Applied Physics A: Materials Science & Processing》2011,104(2):551-558
The three thermal rate equations were built newly up at both ends and at the junction of a p–n diode, in order to derive analytically the temperature difference ΔT (between a junction and both ends) and the internal cooling efficiency η defined newly for a homojunction diode. The maxima ΔT and η of a diode were derived analytically as a function of V
j within the short-length approximation and calculated numerically as a function of V
j or V
bi, where V
j is a voltage across the junction and V
bi is a built-in voltage at the junction. As a result, ΔT increases abruptly with an increase of V
j below V
j=0.050 V or of V
bi below V
bi=0.10 V, while above their values, it increases slowly with an increase of V
j or V
bi to saturate a certain value. For example, ΔT was estimated as 14.6 K for Hg0.8Cd0.2Te diode with V
bi=0.36 V. η has a local maximum of 63% at V
j≈0.01 V or at V
bi≈0.03 V, while above their respective values, it decreases abruptly with an increase of V
j or V
bi and falls to 4.4% at V
bi=0.80 V which is equivalent to that of a diode emitting a laser for fiber optical communication. However, the greater enhancements
in ΔT and η of a diode are required to apply the internal cooling system to a laser-emitting diode which needs the exact control of temperature.
These results should be useful for the application of the internal cooling system to the double heterojunction diode used
in the optical communication. 相似文献
3.
E. M. Aver’yanov 《Journal of Experimental and Theoretical Physics》2010,110(4):622-636
Experimental values of the Lorentz tensor components L
j
for uniaxial quasi-two dimensional “soft matter” objects on substrates (bilayer lipid membranes, multilayer Langmuir films,
smectics A, hexatic smectics B, submicron films of discotics Col
hd
, micron anisotropic films of liquid-crystal comblike polymers and macromolecular polymers, submicron films of conjugated
conductive polymers), freely suspended submicron films of smectics A, and uniaxially stretched micron films of conjugated
conductive polymers have been determined using dispersion of refractive indices in the visible range. The dependences of the
components L
j
on the type of orientation (axial, planar) of uniaxial molecules (structural units of the film) with respect to the optical
axis of the film, the film thickness, the substrate type, the chemical structure of molecules, and their long-range orientational
order are established. It is revealed that the smectic A-hexatic B phase transition and two-dimensional crystallization of
the smectic layer lead to changes in the components L
j
due to the change in the orientational ordering of molecules as a result of the relation between the orientational and hexatic
order parameters. All the above objects are characterized by isotropization of the Lorentz tensor L and the local-field tensor f with a simultaneous decrease in the birefringence of the sample and in the anisotropy of the molecular polarizability due
to the change in the electronic structure of molecules. The correction for the anisotropy of the local-field tensor f to the orientational order parameter or the anisotropy of the molecular polarizability increases. The existing model approaches
to calculating the components L
j
for the objects under consideration are compared with the experimental data. 相似文献
4.
Electroluminescence efficiency in bilayer organic light-emitting devices with LiF/Al cathode 总被引:2,自引:0,他引:2
LI HongJian ZHU RuHui YAN LingLing & ZHANG HaiYan School of Physics Science Technology Central South University Changsha China 《中国科学G辑(英文版)》2007,50(1):31-40
An analytical model to calculate electroluminescence (EL) efficiency of bilayer organic light-emitting devices, considering the influence of introducing LiF insulating buffer layer at metal/organic interface on the barrier height for electron injection, was presented. The relations of EL efficiency versus the applied voltage and injection barrier or internal interfacial barrier or the thickness of organic layer were discussed. The results indicate that: (1) when δ e/δ h < 2, metal/organic (M/O) interface is ohmic contact; when δ e/δ h > 2, M/O becomes contact limited; and when δ e/δ h = 2 (Φ h ~ 0.2 eV, Φ e ~ 0.3 eV), there is a transition from ohmic contact to contact limited; (2) η EL decreases with the increase of δ′e / δ′h; however, when δ′e / δ′h > 2.5 (H ′h~ 0.2 eV, H ′e~ 0.4 eV), the changes of η EL are very small, which shows that η EL is dominated by the carrier’s injection; (3) when increasing Lh/L, η R has a descending trend at low voltage and a rising one at higher voltage. For a given Lh/L, η EL first increases and then decreases with the increasing applied voltage, and as Lh/L further increases, the variation tendency of η EL is more obvious. These conclusions are in agreement with the reported theoretic and experimental results. 相似文献
5.
A. S. Demidov 《Russian Journal of Mathematical Physics》2010,17(2):145-153
For a given domain ω ⋐ ℝ2 with boundary γ = ∂ω, we study the cardinality of the set $
\mathfrak{A}_\eta \left( \Phi \right)
$
\mathfrak{A}_\eta \left( \Phi \right)
of pairs of numbers (a, b) for which there is a function u = u
(a,b): ω → ℝ such that ∇2
u(x) = au(x) + b ⩾ 0 for x ∈ ω, u|
γ
= 0, and ||∇u(s)| − Φ(s) ⩽ η for s ∈ γ. Here η ⩾ 0 stands for a very small number, Φ(s) = |∇(s)| / ∫
γ
|∇v| d
γ, and v is the solution of the problem ∇2
v = a
0
v + 1 ⩾ 0 on ω with v|
γ
= 0, where a
0 is a given number. The fundamental difference between the case η = 0 and the physically meaningful case η > 0 is proved. Namely, for η = 0, the set $
\mathfrak{A}_\eta \left( \Phi \right)
$
\mathfrak{A}_\eta \left( \Phi \right)
contains only one element (a, b) for a broad class of domains ω, and a = a
0. On the contrary, for an arbitrarily small η > 0, there is a sequence of pairs (a
j
, b
j
) ∈ $
\mathfrak{A}_\eta \left( \Phi \right)
$
\mathfrak{A}_\eta \left( \Phi \right)
and the corresponding functions u
j
such that ‖f
u
j+1‖ − ‖f
u
j
‖ > 1, where ‖f
u
j
= max
x∈ω
|f
u
j
(x)| and f
u
j
(x) = a
j
u
j
(x) + b
j
. Here the mappings f
u
j
: ω → ℝ necessarily tend as j → ∞ to the δ-function concentrated on γ. 相似文献
6.
We substantially apply the Li criterion for the Riemann hypothesis to hold. Based upon a series representation for the sequence
{λk}, which are certain logarithmic derivatives of the Riemann xi function evaluated at unity, we determine new bounds for relevant
Riemann zeta function sums and the sequence itself. We find that the Riemann hypothesis holds if certain conjectured properties
of a sequence ηj are valid. The constants ηj enter the Laurent expansion of the logarithmic derivative of the zeta function about s=1 and appear to have remarkable characteristics. On our conjecture, not only does the Riemann hypothesis follow, but an inequality governing the values λn and inequalities for the sums of reciprocal powers of the nontrivial zeros of the zeta function.
Mathematics Subject Classification (2000) 11M26. 相似文献
7.
The energy and centrality independence of the limiting fragmentation for produced mesons have been used to extract the reduced
pseudorapidity (η′ = η − η
beam
) distributions of charged baryons at forward rapidity. The distribution crosses at η′ ≈ = −1 suggesting the prominence of beam protons above that rapidity. The loss of beam rapidity has been extracted which
has been found to increase with centrality. 相似文献
8.
We classify simple linearly compact n-Lie superalgebras with n > 2 over a field ${\mathbb{F}}We classify simple linearly compact n-Lie superalgebras with n > 2 over a field
\mathbbF{\mathbb{F}} of characteristic 0. The classification is based on a bijective correspondence between non-abelian n-Lie superalgebras and transitive
\mathbbZ{\mathbb{Z}}-graded Lie superalgebras of the form L=?j=-1n-1 Lj{L=\oplus_{j=-1}^{n-1} L_j}, where dim L
n−1 = 1, L
−1 and L
n−1 generate L, and [L
j
, L
n−j−1] = 0 for all j, thereby reducing it to the known classification of simple linearly compact Lie superalgebras and their
\mathbbZ{\mathbb{Z}}-gradings. The list consists of four examples, one of them being the n + 1-dimensional vector product n-Lie algebra, and the remaining three infinite-dimensional n-Lie algebras. 相似文献
9.
Gotter M Sottmann T Baciu M Olsson U Wennerström H Strey R 《The European physical journal. E, Soft matter》2007,24(3):277-295
Time-resolved small-angle neutron scattering (TR-SANS) was employed to observe temperature-induced phase transitions from
the sponge (L
3 to the lamellar ( L
α phase, and vice versa, in the water-oil (n -decane)-non-ionic surfactant ( C12E5 system using both bulk and film contrast. Samples of different bilayer volume fractions φ and solvent viscosities η were
investigated applying various amplitudes of temperature jump ΔT . The findings of a previous 2H -NMR study could be confirmed, where the lamellar phase formation was determined to occur through a nucleation and growth
process, while it was concluded that the L
3 -phase develops in a mechanistically different and more rapid manner involving uncorrelated passage formation. Likewise,
the kinetic trends of the nucleation and growth transition (decreased transition time with increase of φ and ΔT were witnessed once again. Additionally, NMR and SANS data that demonstrate a strong dependency of that process on solvent
viscosity η are presented. Contrariwise, it is made evident via both SANS and NMR results that the L
α -to-L
3 transition time is independent (within experimental sensitivity) of the varied parameters (φ , ΔT , η . Unusual scattering evolution in one experiment, originating from a highly ordered lamellar phase, intriguingly hints
that a major rate determining factor is the disruption of long-range order. Furthermore, the bulk contrast investigations
give insight into structure peak shifts/development during the transitions, while the film contrast experiments prove the
bilayer thickness to be constant throughout the phase transitions and show that there is no evidence for a change in the short-range
order of the bilayer structure. The latter was considered possible, due to the different topology of the L
3 and L
α phases. Lastly, an unexpected yet consistent appearance of anisotropic scattering is detected in the L
3 -to- L
α transitions. 相似文献
10.
High-statistics Belle data on the γγ → π0η reaction have been analyzed in order to reveal the mechanism of two-photon production and the nature of the a
0(980) resonance. The solution obtained for the γγ → π0η amplitude is in agreement with the predictions of the chiral theory for the πη-scattering length; with the strong coupling
of the a
0(980) resonance with the πη, K
$
\bar K
$
\bar K
, and πη′ channels; and with the key role of the a
0(980) → (K
$
\bar K
$
\bar K
+ π0η + π0η′) → γγ rescattering mechanisms in the a
0(980) → γγ decay. This picture is much in favor of the q
2
$
\bar q
$
\bar q
2 nature of a
0(980) resonance and is consistent with the properties of its partners, σ0(600) and f
0(980) resonances, in particular, with those manifested in the γγ → ππ reactions. The important role of vector exchanges in
the formation of the nonresonant background in the γγ → π0η reaction has been revealed. Preliminary information on the π0η → π0η reaction has been obtained. 相似文献
11.
L. Palladino A. Reale G. Taglieri D. Batani S. Bollanti P. Di Lazzaro F. Flora T. Letardi G. Schina M. Belli A. Scafati 《Il Nuovo Cimento D》1993,15(8):1133-1146
Summary We present a detailed study of XUV and soft X-ray emission from Cu plasma produced by an excimer laser at intensitiesI
L≦8·1011 W/cm2. The XeCl excimer laser (ψ≈308 nm) delivers pulses with energyE
L≈2.3 J, temporal durationt
L≈100 ns and brightnessB≧1014 W/cm2 sr. We recorded a spectral conversion efficiency η=0.5% eV−1 forI
L=4·1011W/cm2 in the aluminium window at 73eV with a harder X-ray tail around ≈400eV. We also measured the dependence of X-ray signal on
laser intensity and viewing angle. Experimental results have been compared with some analytical laser-plasma interaction models. 相似文献
12.
V. D. Lakhno 《Journal of Experimental and Theoretical Physics》2010,110(5):811-815
A theory of a strong-coupling large-radius bipolaron has been developed. The possibility of the formation of 3D bipolarons
in high-temperature superconductors is discussed. For the bipolaron energy, the lowest variational estimate has been obtained
at α > 8, where α is the electron-phonon coupling constant. The critical ionic-bond parameter η
c
= ɛ∞/ɛ0, where ɛ∞ and ɛ0 are the high-frequency and static dielectric constants, has been found to be η
c
= 0.2496. 相似文献
13.
The critical properties and phase transitions of the three-dimensional frustrated antiferromagnetic Heisenberg model on a
triangular lattice have been investigated using the Monte Carlo method with a replica algorithm. The critical temperature
has been determined and the character of the phase transitions has been analyzed using the method of fourth-order Binder cumulants.
A second-order phase transition has been found in the three-dimensional frustrated Heisenberg model on a triangular lattice.
The static magnetic and chiral critical exponents of the heat capacity α, the susceptibility γ and γ
k
, the magnetization β and β
k
, the correlation length ν and ν
k
, as well as the Fisher exponents η and η
k
, have been calculated in terms of the finite-size scaling theory. It has been demonstrated that the three-dimensional frustrated
antiferromagnetic Heisenberg model on a triangular lattice forms a new universality class of the critical behavior. 相似文献
14.
Ching-Liang Wei Ying-Chung Chen Chien-Chuan Cheng Kuo-Sheng Kao 《Applied Physics A: Materials Science & Processing》2008,91(3):501-506
Bright and efficient stacked color-tunable organic light emitting devices (OLEDs) using an intermediate Al/Au electrode have
been reported. The effects of the thicknesses of Al and Au layers on the luminance characteristics have been comprehensively
studied. After optimization, the bottom-emission single-unit OLED of 4,4′,4′′-Tris(N-3-methylphenyl-N-phenyl-amino) triphenylamine/N,N′-diphenyl-N,N′-bis(1-naphthyl)-(1,1′-biphenyl)-4,4′-diamine/tris(8-hydroxyquinoline) aluminum has a maximum luminance efficiency (ηL) of 3.37 cd/A by using Al/Au as the cathode and 2.92 cd/A by using Al/Au as the anode. Meanwhile, by introducing the optimized
intermediate Al/Au electrode into the stacked color-tunable (red to blue) OLEDs, a red unit with maximum ηL of 4.73 cd/A and a blue unit with maximum ηL of 3.96 cd/A have been obtained. The color can be tuned efficiently along a linear route from pure red with the Commission
Internationale de l’Eclairage (CIE) coordinates of (0.662, 0.330) to sky blue with the CIE coordinates of (0.155, 0.340).
This scheme can be a potential candidate for achieving high-brightness and efficient stacked color-tunable OLEDs.
PACS 78.60.Fi; 78.66.Qn; 81.05.Lg; 85.30.De 相似文献
15.
Mixing angles of η and η′ mesons are obtained in the scheme of octet-singlet mixing θη = −15.4°, θ′η = −17.9°, and in the scheme connected with expansion in the quark basis $
\bar q
$
\bar q
q − $
\bar s
$
\bar s
s φ = 39.3°. The constants gV
ηγ, g
η′
V
γ of radiative decays η′ → V
γ and V → ηγ (V ≡ ρ, ω, φ) and the ratios of constants of weak decays of η and η′ mesons are calculated. The numerical values that were found
are in agreement with the experimental data. 相似文献
16.
Complex eigenphases and mixing parameters for elastic n-d scattering above the breakup threshold are calculated. Faddeev equations are solved precisely using the Bonn-B NN potential. We point out defects in existing N-d phase-shift analyses. Peculiar energy variations in the mixing parameter η3/2− are shown to have no effect on observables and are simply an artifact of the S-matrix parametrization. It is shown, that the n-d analyzing power A
y
depends most sensitively on the three eigenphases δ1/2
3/2/1, δ2/3
3/2/1, and δ5/2
3/2/1, which again are predominantly generated by the 3
P
j
NN force components. Therefore a determination of those eigenphases from experimental data would help to constrain the 3
P
j
NN forces.
Received September 26, 1994; accepted for publication December 15, 1994 相似文献
17.
N.V. Shevchenko V.B. Belyaev S.A. Rakityansky S.A. Sofianos W. Sandhas 《The European Physical Journal A - Hadrons and Nuclei》2000,9(1):143-146
Elastic ηd-scattering is considered within the Alt-Grassberger-Sandhas (AGS) formalism for various ηN input data. A three-body resonant state is found close to the ηd threshold. This resonance is sustained for different choices of the two-body ηN-scattering length a
ηN. The position of the resonance moves towards the ηd threshold when Rea
ηN is increased, and turns into a quasi-bound state at Rea
ηN∼ 0.7-0.8 fm depending on the choice of Ima
ηN.
Received: 12 June 2000 / Accepted: 3 August 2000 相似文献
18.
The current-voltage characteristics of granular YBa2Cu3O6.95 high-temperature superconductor samples have been measured at a temperature of 77.3 K in external transverse magnetic fields
H
ext with a strength of up to H
ext ≈ 500 Oe for low transport current densities (0.1 A/cm2 ≤ j ≤ 0.6 A/cm2). The current-voltage characteristics obtained have been used to construct dependences of the magnetoresistance ρ on the
quantities j (ρ(j)
Hext=const) and H
ext(ρ(H
ext)
j = const). It has been revealed that the current and field dependences of the magnetoresistance exhibit anomalies at H
ext ≥ H
c1g
, where H
c1g
is the lower critical field of superconducting grains. A comparative analysis of the dependences ρ(j)H
ext = const and ρ(H
ext)
j = const has made it possible to develop concepts regarding the influence of the processes of redistribution of the magnetic field
between grain boundaries and superconducting grains on the transport and galvanomagnetic properties of granular high-temperature
superconductors. It has been established that the field dependences of the magnetoresistance exhibit specific features associated
with the beginning of penetration of Josephson vortices into grain boundaries in the magnetic field H
c1J
and with the breaking of a continuous chain of Josephson junctions in the magnetic field H
c2J
. 相似文献
19.
V.A. Khoze A.D. Martin M.G. Ryskin 《The European Physical Journal C - Particles and Fields》2006,48(2):467-475
We propose a new variable, Rj, in order to identify exclusive double-diffractive high ET di-jet production. The variable Rj is calculated using the transverse energy ET and pseudorapidity of the jet with the largest ET. For a purely exclusive event the value of Rj→1, if we were to neglect hadronisaton and the detector resolution effects. To illustrate the expected Rj distribution we also compute exclusive three-jet production; and, moreover, we include jet smearing effects. By studying the predictions as a function of the size of the rapidity interval, δη, which allows for additional gluon radiation, one can probe the QCD radiation effects which are responsible for the Sudakov suppression of the exclusive amplitude. In this way we may check and improve the formalism used to predict the cross sections of exclusive double-diffractive Higgs boson (and/or other new physics) production. 相似文献
20.
The microscopic scenario of vortex escape from a columnar defect under the influence of a transport current has been studied.
For defect radii smaller than the superconducting coherence length the depinning process is shown to be a consequence of two
subsequent topological electronic transitions in a trapped vortex core. The first transition at a critical current j
L
is associated with the opening of Fermi surface segments corresponding to the creation of a vortex-antivortex pair bound
to the defect. The second transition at a certain current j
d
> j
L
is caused by merging of different Fermi surface segments, which accompanies the formation of a freely moving vortex. 相似文献