共查询到20条相似文献,搜索用时 28 毫秒
1.
Vladimir G. Neudatchin Igor T. Obukhovsky Ludmila L. Sviridova Nikolai P. Yudin 《Central European Journal of Physics》2004,2(3):511-522
The pion momentum distributions (MDs) in four channels of virtual decay p→B+π, B = N, Δ, N
1/2-(1535), N
1/2+(1440) are calculated in two models, the microscopic model of 3
P
0 scalar q−q fluctuation with the pion as a composite q−q-system and the chiral semi-microscopic model of πq interaction with the pion as a structureless Goldstone boson. The results of the above models are similar for the baryon
states B = N, Δ, N
1/2-(1535) but are rather different for the Roper resonance N
1/2+(1440) which corresponds to excitation of two oscillator quanta in the nucleon. The experimental investigation of pion MDs
by means of the reaction of quasi-elastic knockout of pion by an electron of a few GeV energy p(e, e′ π)B may be very suitable for Jefferson Laboratory, Virginia (JLab). 相似文献
2.
H.Y. Wang Z.W. Ma E.Y. Jiang Y.J. He H.S. Huang 《Applied Physics A: Materials Science & Processing》1999,68(5):559-562
The structure and magnetic properties of Fe-N and Fe-Ti-N films have been studied as a function of annealing temperature Ta with a transmission electron microscope and a vibrating sample magnetometer. The as-prepared Fe-N films consist of the γ′-Fe4N and α′′-Fe16N2 phases, and the Fe-Ti-N films are composed of the γ′-Fe4N, α′′-Fe16N2, and TiN phases. The structural changes with annealing temperature in the Fe-N films are distinct. The α′′-Fe16N2 decomposes into α+γ′ phases in the Fe-N film annealed at about 300 °C, and it disappears in the film annealed at 350 °C. Annealing of the Fe-Ti-N
films shows no structural changes between room temperature (RT) and 500 °C. The saturation magnetization 4πMS and coercivity Hc of the Fe-N films change drastically with the annealing temperature Ta, whereas those of the Fe-Ti-N films do not change with Ta up to 500 °C. These results indicate that the additon of Ti may improve the thermal stability of Fe-N films.
Recieved: 6 Juli 1998 / Accepted: 19 Oktober 1998 / Published online: 10 March 1999 相似文献
3.
M. K. Srivastava 《Pramana》2004,63(5):1053-1062
An approximate simple scaling law is obtained for asymmetric (e, 3e) process on helium-like ions for double ionization by fast electrons. It is based on the equation (Z
′3π) exp[-Z(r1 + r2)],Z′ = Z – (5/16) for ground state wave function of helium-like ions and Z′2 scaling of energies. The scaling law is found to work very well if the lower energy electron is ejected along the momentum
transfer direction and the other one is ejected in the opposite direction. It also works quite well if this electron is ejected
within about 90° of the momentum transfer direction with the other electron going in the opposite direction. The scaling law
becomes increasingly accurate as the target nuclear charge and the energy increase. 相似文献
4.
Hungchong Kim 《The European Physical Journal A - Hadrons and Nuclei》2000,7(1):121-125
Within the conventional QCD sum rules, we calculate the πNN coupling constant, g
πN, beyond the chiral limit using two-point correlation function with a pion. For this purpose, we consider the Dirac structure,
iγ5, at m
π
2 order in the expansion of the correlator in terms of the pion momentum. For a consistent treatment of the sum rule, we include
the linear terms in quark mass as they constitute the same chiral order as m
π
2. In this sum rule, we obtain g
πN= 13.3 ± 1.2, which is very close to the empirical πNN coupling. This demonstrates that going beyond the chiral limit is crucial in determining the coupling.
Received: 8 July 1999 / Revised version: 20 August 1999 相似文献
5.
G.I. Lykasov W. Cassing A. Sibirtsev M.V. Rzjanin 《The European Physical Journal A - Hadrons and Nuclei》1999,6(1):71-81
We calculate the elastic and inelastic ωN→ωN, →πN, →ρN, →ρπN, →ππN, →σN reactions within a boson exchange approximation where the ωρπ coupling constant and form factor are fixed by the reaction
πN→ωN in comparison to the experimental data. We find rather large ωN cross sections at low relative momenta of the ω-meson which
leads to a substantial broadening of the ω-meson width in nuclear matter. The implications of the ωN final state interactions are studied for ω production in 12C +12C, 40Ca +40Ca and 58Ni +58Ni reactions at about 2 · A GeV within the HSD transport approach; the drastic changes of the transverse mass spectra relative
to a general m
T-scaling (for π0 and η mesons) might be controlled experimentally by the TAPS Collaboration.
Received: 28 April 1999 / Revised version: 7 June 1999 相似文献
6.
A. A. Volod’kin G. E. Zaikov L. N. Kurkovskaya E. B. Burlakova 《Russian Journal of Physical Chemistry B, Focus on Physics》2011,5(5):836-845
The energies of formation, enthalpies, and entropies of the conformers of 1-(carboxy)-1-(N-methylamide)-2-(3′,5′-di-tert-butyl)-4-hydroxyphenyl)-propionic acid and sodium and potassium 1-(carboxy)-1-(N-methylamide)-2-(3′,5′-di-tert-butyl)-4-hydroxyphenyl)-propionates are calculated by quantum-chemical methods in the PM6 approximation. A doubling of signals
in the 1H NMR spectrum of the first conformer is observed, which merge into singlets when the compound is heated. Changes in the structure
of the conformers and donor-acceptor complexes (solvates) occur with the preservation of the metal-ligand coordination bond.
Calculations of the characteristics of 1-(carboxy)-1-(N-methylamide)-2-(3′,5′-di-tert-butyl)-4-hydroxyphenyl)-propionic acid and sodium and potassium 1-(carboxy)-1-(N-methylamide)-2-(3′,5′-di-tert-butyl)-4-hydroxyphenyl)-propionates in the PM6 approximation make it possible to predict the structure and properties of
the solvated structures. The energies of homolysis of the H-O bond D
(OH) are calculated, and a linear dependence of the antioxidant activity on D
(OH) for the structures of the studied compounds is demonstrated. The results make it possible to predict the properties of antioxidants
in the biological environment. 相似文献
7.
I. Y. Erukhimovich A. Johner J. F. Joanny 《The European physical journal. E, Soft matter》2008,27(4):435-445
We present a new ab initio approach to describe the statistical behavior of long ideal polymer chains near a plane hard wall. Forbidding the solid half-space
to the polymer explicitly (by the use of Mayer functions) without any other requirement, we derive and solve an exact integral
equation for the partition function G
D(r,r′, N) of the ideal chain consisting of N bonds with the ends fixed at the points r and r′ . The expression for G(r,r′, s) is found to be the sum of the commonly accepted Dirichlet result G
D(r,r′, N) = G
0(r,r′, N) - G
0(r,r”, N) , where r” is the mirror image of r′ , and a correction. Even though the correction is small for long chains, it provides a non-zero value of the monomer density
at the very wall for finite chains, which is consistent with the pressure balance through the depletion layer (so-called wall
or contact theorem). A significant correction to the density profile (of magnitude 1/is obtained away from the wall within one coil radius. Implications of the presented approach for other polymer-colloid problems
are discussed. 相似文献
8.
A combined analysis of photoproduction data on γp↦ πN, ηN was performed including the data on KΛ and KΣ. The data are interpreted in an isobar model with s-channel baryon resonances and π, ρ (ω), K, and K
* exchange in the t-channel. Three baryon resonances have a substantial coupling to ηN, the well-known N(1535)S
11, N(1720)P
13, and N(2070)D
15. The inclusion of data with open strangeness reveals evidence for further new resonances, N(1840)P
11, N(1875)D
13 and, with weaker evidence, for N(2170)D
13. 相似文献
9.
We calculate the process np → ηd near threshold using a separable potential model of the coupled ηN - πN - ππN subystems, and a relativistic three-body calculation for the ηd scattering amplitude. The ππN channels are represented by an effective σN channel, and we compare the case where the σ and π masses are related by m
σ = 2m
π and no width is considered, to another where the mass and width of the σ -meson are taken from ππ scattering data. The np → ηd cross-section can be well described up to about 60MeV by models where the real part of the ηN scattering length lies between 0.4≤Re(a
ηN)≤0.6 fm which allows us to determine the s -wave ηN scattering amplitude for -60≤E≤60 MeV. 相似文献
10.
This study examined the electrical and optical properties of red OLEDs (organic light-emitting diodes) with a four-layer structure,
ITO/amorphous fluoropolymer (AF)/N,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1-biphenyl-4,4′-diamine (TPD)/R-H:R-D/lithium fluoride (LiF)/Al, containing a hole injection material,
AF (amorphous fluoropolymer) and an electron injection layer material, LiF. Compared to the basic structure (two-layer structure),
the brightness and luminous efficiency of the four-layer structure, ITO/TPD/R-H:R-D/Al, increased approximately 100 times
(30,000 lm/m2) and 150 times (51 lm/W), respectively, with an applied voltage. The excellent efficiency of the external proton was also
increased 150 times (0.51%). That is, the hole and electron injection layers improved the surface roughness of ITO and Al,
and the interfacial physical properties. In addition, these layers allowed the smooth injection of holes and electrons. The
luminance, luminous efficiency and external quantum efficiency were attributed to an increase in the recombination rates. 相似文献
11.
Zhaokui Wang Shigeki Naka Hiroyuki Okada 《Applied Physics A: Materials Science & Processing》2011,102(3):681-687
Injection properties of electrons and holes in a mixed single layer organic light emitting device with mixed small molecules
tris-(8-hydroxy-quinoline) aluminum (Alq3), 2,5-bis(6′-(2′,2″-bipyridyl))-1,1-dimethyl-3,4-diphenylsilole (PyPySPyPy), 4′-bis[N-(1-napthyl)-N-phenyl-amino]biphenyl
(α-NPD), and 5,6,11,12-tetraphenylnaphthacene (rubrene) were investigated using Au/MoO3 as hole and Al alloy as electron injection electrodes. On the basis of measuring the temperature dependence of currents through
the interface between the electrodes and the mixed single organic layer, the carrier injection mechanism was primarily ascribed
to the Schottky thermionic emission with the barrier height of 0.25 eV for holes and 0.67 eV for electrons. By adding the
dopant material rubrene and the electron transport material PyPySPyPy into the mixed single layer, the barrier height of electrons
could be reduced. The interfacial state analysis demonstrated that the electron barrier height was also dependent on the interfacial
conditions of the device. 相似文献
12.
M. Schumacher 《The European Physical Journal A - Hadrons and Nuclei》2006,30(2):413-422
The t-channel contribution to the difference of electromagnetic polarizabilities of the nucleon, (α - β)t, can be quantitatively understood in terms of a σ-meson pole in the complex t-plane of the invariant scattering amplitude A
1(s, t) with properties of the σ-meson as given by the quark-level Nambu-Jona-Lasinio model (NJL). Equivalently, this quantity may
be understood in terms of a cut in the complex t-plane where the properties of the σ-meson are taken from the ππ → σ → ππ, γγ → σ → ππ and Nˉ → σ → ππ reactions. This equivalence may be understood as a sum rule where the properties of the σ-meson as predicted by
the NJL model are related to the f
0(600) particle observed in the three reactions. In the following, we describe details of the derivation of (α - β)t making use of predictions of the quark-level NJL model for the σ-meson mass.
An erratum to this article is available at . 相似文献
13.
V. Dorofeev R. Dzhelyadin A. Ekimov Yu. Gavrilov Yu. Gouz A. Ivashin V. Kabachenko I. Kachaev A. Karyukhin Yu. Khokhlov V. Konstantinov M. Makouski V. Matveev A. Myagkov V. Nikolaenko A. Ostankov B. Polyakov D. Ryabchikov N. Shalanda M. Soldatov A. A. Solodkov A. V. Solodkov O. Solovianov E. Starchenko A. Zaitsev 《The European Physical Journal A - Hadrons and Nuclei》2008,38(2):149-154
The isospin-violating decay f
1(1285) → π+π-π0 has been studied at the VES facility. This study is based on the statistics acquired in π-
Be interactions at 27, 36.6 and 41 GeV/c in the diffractive reaction π-
N → (f
1π-)N . The f
1(1285) → π+π-π0 decay is observed. The preliminary ratio of decay probabilities BR(f
1(1285) → π+π-π0) to BR(f
1(1285) → ηπ+π-).
BR(η → γγ) is ∼ 2% .
Original article based on material presented at HADRON 2007. 相似文献
14.
V.V. Anisovich A.V. Sarantsev 《The European Physical Journal A - Hadrons and Nuclei》2003,16(2):229-258
We present the results of the current analysis of the partial wave IJ
PC = 00+ + based on the available data for meson spectra ( ππ, KˉK,ηη,η,ππππ). In the framework of the K-matrix approach, the analytical amplitude has been reconstructed in the mass region 280 MeV < < 1900 MeV. The following scalar-isoscalar states are seen: comparatively narrow resonances f
0(980), f
0(1300), f
0(1500), f
0(1750) and the broad state f0(1200-1600). The positions of the amplitude poles (masses and total widths of the resonances) are determined as well as pole
residues (partial widths to meson channels ππ, KˉK,ηη,η,ππππ). The fitted amplitude gives us the positions of the K-matrix poles (bare states) and the values of bare-state couplings to meson channels thus allowing the quark-antiquark nonet
classification of bare states. On the basis of the obtained partial widths to the channels ππ, KˉK,ηη,η, we estimate the quark/gluonium content of f
0(980), f
0(1300), f
0(1500), f
0(1750), f0(1200-1600). For f
0(980), f
0(1300), f
0(1500) and f
0(1750), their partial widths testify the qˉq origin of these mesons though being unable to provide precise evaluation of the possible admixture of the gluonium component
in these resonances. The ratios of the decay coupling constants for the f0(1200-1600) support the idea about the gluonium nature of this broad state.
Received: 14 May 2002 / Accepted: 20 August 2002 / Published online: 11 February 2003
RID="a"
ID="a"e-mail: anisovic@thd.pnpi.spb.ru
Communicated by A. Sch?fer 相似文献
15.
Bo Jiao Zhaoxin Wu Xingwei Yan Xun Hou 《Applied Physics A: Materials Science & Processing》2010,98(1):239-243
We investigated the influence of the thickness of hole-transport layer, N,N′-biphenyl-N,N′-bis(1-naphthyl)-(1,1′-biphenyl)-4,4′-diamine (NPB), on the performance of the typical bi-layer organic light-emitting diodes
(OLEDs). It was found that both the current efficiency and the power efficiency of bi-layer OLEDs were improved when the thickness
of the hole-transport layer varied from 30 to 120 nm. By investigating the hole-injection efficiency of ITO/NPB contact with
various thicknesses of NPB film, we found that the hole-injection efficiency was reduced with the thickness of NPB layer increasing
from 60 to 180 nm, which improved the injected carriers balance in devices and increased the efficiency of the bi-layer OLEDs. 相似文献
16.
Tuning of the emission color of organic electroluminescent devices by exciplex formation at the organic solid interface 总被引:1,自引:0,他引:1
′ ,4′′-tris(3-methylphenylphenylamino)triphenylamine, 1,3,5-tris[(4-diphenylaminophenyl)phenylamino]benzene, N, N′-bis(3-methylphenyl)-N, N′-diphenyl-[1,1′-biphenyl]-4,4′-diamine, and 4,4′,4′′-tri(N-carbazolyl)triphenylamine, emitted bright light resulting from the exciplex formed at the solid interface between TPOB
and the hole-transporting material. The exciplex formation was evidenced by the measurements of the photoluminescence spectra
and lifetimes of the mixture of an equimolar amount of TPOB and each of the hole-transporting materials. Tuning of the emission
color from greenish blue to orange was attained by varying the ionization potential of the hole-transporting material for
the fixed electron-transporting material of TPOB.
Received: 27 July 1998/Accepted: 28 July 1998 相似文献
17.
M. Diegelmann H. P. Grieneisen K. Hohla Xue-Jing Hu J. Krasinski K. L. Kompa 《Applied Physics A: Materials Science & Processing》1980,23(3):283-287
As an outcome of a systematic study of excitation kinetics and fluorescence spectra concerning theD′(3π2u
)→A′(3π2g
) transitions in homonuclear diatomic halogens and corresponding transitions in interhalogen molecules [1], this paper describes,
for the first time, TEA laser action in the three halogen monofluorides ClF, BrF, and IF. Output energies in the mJ range
were demonstrated in a fast TEA discharge arrangement at the wavelengths of 284.4, 354.5, and 490.8 nm for ClF, BrF, and IF,
respectively. The results suggest parameter scalability and wavelength tunability. 相似文献
18.
Both phosphorescent materials and devices, which emit red and green light, already have great performance and breakthrough.
The biggest challenge and bottleneck is the blue phosphorescent device, if we want to popularize phosphorescent organic light-emitting
device (OLED) in the full-color panel. This paper brings a new quantum-well structure in light-emitting layer. We select the
commonly used phosphor materials, N,N′-dicarbazoly-2,5-benzene (mCP) and bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl)iridium(III) (FIrpic). The structure
of the device is indium-tin oxide (ITO)/N,N′-bis(naphthalene-1-y1)-N,N′-bis(phenyl)-benzidine (NPB)/di-[4-(N,N-ditolyl-amino)-phenyl]cyclohexane (TAPC)/mCP/FIrpic/mCP/4,7-dipheny1-1,10-phenanthroline (Bphen)/Mg:Ag. The blue OLED of
good performance is achieved by adjusting the thickness of FIrpic. When the thickness of FIrpic is 0.2 nm and the Current
density is 34.86 mA/cm2, the results show that the luminance of the device is 1000 cd/m2, then the luminous power efficiency of the device is 6.01 lm/W. Meanwhile, the light emitting mechanism of ultrathin quantum-well
structure is well studied, the quantum confinement effect and the role of quantum well structure as the light-emitting layer
in the blue phosphorescent devices are mainly analyzed. 相似文献
19.
B.S. Zou G.X. Peng R.G. Ping H.C. Chiang W.X. Ma P.N. Shen 《The European Physical Journal A - Hadrons and Nuclei》2001,11(3):341-344
For J/Ψ↦
pπ0 and
pπ+π-, the π0
p and pπ+π- systems are limited to be pure isospin-(1/2) due to isospin conservation. This is a big advantage in studying N* resonances from J/Ψ decays, compared with πN and γN experiments. The process J/Ψ↦
N
* or p
provides a new way to probe the internal structure of the N* resonances. Here we report a quark model calculation for J/Ψ↦
p,
N
*(1440) and
N
*. The implication for the internal structure of N
*(1440) is discussed.
Received: 1 June 2001 / Accepted: 20 June 2001 相似文献
20.
Two novel and neutral benzimidazole derivatives-based anion receptors bearing a 1,10-phenanthroline fluorophore, N,N′-di-(2′-benzimidazolyl-methylene)-1, 10-phenanthroline-2,9-diamide (1) and N,N′-di-[2′-(benzimidazolyl-2′-) ethyl-]-1,10-phenanthroline-2,9-diamide (2), which exhibited turn-on and turn-off fluorescence
responses to various anions, were rationally designed and synthesized and their fluorescent response toward anions was investigated
in DMSO solution. In the process of anions binding, there were two different fluorescent responses in presence of anions:
a quenching of the fluorescence emission for F- and AcO- and an enhancement of the fluorescence emission for Cl−, Br− and I−. Two different luminescent mechanisms of the receptors 1 and 2 resulting from various anions were exploited to rationalize
quenching and enhancement of the fluorescence emission: a photo-induced electronic transfer mechanism (PET) and the increase
of the rigidity of the host molecules, respectively. In particular, chloride could be recognized selectively from the anions
tested according to changes of fluorescence spectrum.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献