共查询到20条相似文献,搜索用时 10 毫秒
1.
J. Blasco J. García M.C. Sánchez J. Campo G. Subías J. Pérez-Cacho 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,30(4):469-479
Magnetic measurements have been carried out in different LaNi1-xMnxO
3 + δ
samples with 0.1 ⩽
x
⩽ 0.9. All these samples show two magnetic anomalies, one at relatively high temperature characteristic of a ferromagnetic ordering
and the other at low temperature, typical of magnetic relaxation phenomena. Neutron diffraction patterns indicate that long-range
ferromagnetic ordering is only achieved for x
≥ 0.5. Neutron patterns of LaNi0.5Mn0.5O
3 + δ
samples show an ordered arrangement of Ni and Mn atoms in the perovskite lattice. LaNi0.5Mn0.5O
3 + δ
is then, a double perovskite A2BB'O6 whereas Ni and Mn atoms are randomly distributed for the rest of the samples. X-ray magnetic circular dichroism experiments
confirm the presence of collinear ferromagnetism in LaNi0.5Mn0.5O
3 + δ
. The role of competitive magnetic interactions, structural disorder, magnetic anisotropy and magnetic disaccommodation is
also discussed
Received 19 July 2002 / Received in final form 23 October 2002 Published online 31 December 2002 相似文献
2.
A. Kanaev L. Museur F. Edery T. Laarmann T. Möller 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(2):261-268
We have studied the fluorescence of electronically excited OH*, H* and H2O+* dissociation fragments after VUV excitation ( h
ν≥11.6
eV) of rare-gas clusters (Rg = Ne, Ar) doped with H2O molecules. In contrast to a free molecule, where Balmer H-series dominate the UV-visible spectra, only the OH
*
(
A
2
Σ
+
↦
X
2
Π) emission band is observed in neon clusters. No emission of excited water ions has been observed. We find that while higher
excitation energies (Ne vs. Ar) induce higher vibrational excitation of the OH*
(
A
) fragment, the rotational temperature is lower. This effect is attributed to the difference in the geometric position of the
H2O molecule on the surface or inside the Rg-cluster. The rotational relaxation in neon clusters is rapid while the vibrational
relaxation is slow because of the coupling with the low energy matrix phonons.
Received 7 March 2002 / Received in final form 27 May 2002 Published online 19 July 2002 相似文献
3.
O.-H. Kwon H. Yoo D.-J. Jang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(1):69-75
While the intercalation of C60 and the formation of C
60
-
in the supercages of NaX and NaY are confirmed by using 129Xe NMR and ESR, the photophysical properties of C60 and C
60
-
are characterized by monitoring transient reflectance spectra and kinetics, fluorescence kinetics, and diffuse reflectance
spectra. C
60
-
is considerably more abundant in NaY than in NaX. This difference is explained in terms of polarity difference between two
zeolites. Both C60 and C
60
-
have remarkably elongated excited-state lifetimes due to their collision-free environment in zeolitic nanocavities although
C
60
-
has much shorter lifetimes than C60. C
60
-
, in particular, shows intense absorption and emission due to its reduced symmetry in zeolites.
Received 13 July 2001 and Received in final form 8 October 2001 相似文献
4.
A. Bielski D. Lisak R.S. Trawiński J. Szudy 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(2):217-222
Using a laser-induced fluorescence method a detailed analysis of profiles of the 114Cd 326.1 nm line perturbed by N2 and CH4 was performed which revealed deviations from the ordinary Voigt profile. These deviations are shown to be consistent with
fits of experimental profiles to an asymmetric Voigt profile. Coefficients of the pressure broadening, shift and collision-time
asymmetry are determined and compared with those calculated for van der Waals interaction potential.
Received 29 November 2001 / Received in final form 12 July 2002 Published online 4 February 2003 相似文献
5.
N. Oshimo 《The European Physical Journal C - Particles and Fields》2005,39(3):383-388
The measurability of generation mixing is studied on pair production of sneutrinos in e
+
e
- collisions and their subsequent decays into two different charged leptons e and μ with two lighter charginos. The analyses are made systematically in a general framework of the supersymmetric extension
of the standard model. The production and decay process depends on the parameters of the chargino sector as well as those
of the sneutrino sector. Although generation-changing interactions are severely constrained by radiative charged-lepton decays,
sizable regions in the parameter space could still be explored at e
+
e
- colliders in the near future.
Received: 6 October 2004, Revised: 14 November 2004, Published online: 14 January 2005
PACS:
11.30.Hv, 12.15.Ff, 12.60.Jv, 14.80.Ly 相似文献
6.
7.
G. Pancheri O. Shekhovtsova G. Venanzoni 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):458-460
Effects due to the non-pointlike behaviour of pions in the process e
+
e
-→π
+
π
-
γ can arise for hard photons in the final state. By means of a Monte Carlo event generator, which also includes the contribution
of the direct decay φ→π
+
π
-
γ, we estimate these effects in the framework of the resonance perturbation theory. We consider angular cuts used in the KLOE
analysis of the pion form factor at threshold. A method to reveal the effects of the non-pointlike behaviour of pions in a
model-independent way is proposed. 相似文献
8.
A. Gasparyan J. Haidenbauer C. Hanhart K. Miyagawa 《The European Physical Journal A - Hadrons and Nuclei》2007,32(1):61-67
The prospects of utilizing the strangeness production reaction γd→K
+
Λn for the determination of the Λn low-energy scattering parameters are investigated. The spin observables that need to be measured in order to isolate the
Λn singlet (1
S
0) and triplet (3
S
1) states are identified. Possible kinematical regions where the extraction of the Λn scattering lengths might be feasible are discussed. 相似文献
9.
P. Orgiani C. Aruta G. Balestrino S. Lavanga P.G. Medaglia A. Tebano 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,26(1):23-28
Transport properties of SrRuO3 thin films were studied as a function of the epitaxial strain. SrRuO3 films were grown on (100) SrTiO3 substrates by the Pulsed Laser Deposition technique equipped with Reflection High Energy Electrons Diffraction (RHEED). Samples
thickness has been varied from a few unit cells to above 1000 ? while monitoring RHEED intensity oscillations. In thicker
films epitaxial strain was found to be progressively relaxed. SrRuO3 relaxed films (thickness 1000 ?) show metallic behavior for the whole temperature range with a ferromagnetic ordering at about 150 K. For thinner
films, ferromagnetic ordering occurs at progressively lower temperatures, until in films thinner than 400 ? it disappears.
Films thinner than 80 ? show a semiconducting behavior at low temperatures. Our results provide direct evidence of the crucial
role of the strain effect for conducting and magnetic properties of SrRuO3.
Received 16 July 2001 and Received in final form 22 October 2001 相似文献
10.
Born differential cross sections and the lowest-order radiative correction to them are obtained in the kinematics of large-angle
final photon emissions in high-energy electron-positron annihilation processes. Taking into account the possible emission
of real soft and hard photons in collinear kinematics, we show the validity of the Drell-Yan form of the differential cross
section with the nonsinglet structure functions of the initial leptons. The leading and next-to-leading contribution to the
cross sections is obtained. The relevant numerical estimations are presented.
The text was submitted by the authors in English. 相似文献
11.
N. N. Achasov 《Physics of Atomic Nuclei》2007,70(5):862-863
It is argued that the realization of gauge invariance condition as a consequent of cancellation between the ϕ → γf
0 → γπ
0
π
0 resonance contribution and the ϕ → γπ
0
π
0 background one, suggested by A.V. Anisovich et al., Yad. Fiz. 68, 1614 (2005), is misleading.
The text was submitted by the author in English. 相似文献
12.
Toshiyuki Abe Chongying Dong Haisheng Li 《Communications in Mathematical Physics》2005,253(1):171-219
The fusion rules for the vertex operator algebras M(1)+ (of any rank) and V+L (for any positive definite even lattice L) are determined completely.Supported by JSPS Research Fellowships for Young ScientistsPartially supported by NSF grants and a research grant from the Committee on Research, UC Santa CruzPartially supported by a NSA grant and a grant from Rutgers University Research Council 相似文献
13.
R. Escribano 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):454-457
The scalar contributions to the radiative decay φ→K
0ˉ0
γ are studied within the framework of the Linear Sigma Model (LσM). Theoretical predictions for the associated subprocesses φ→f
0
γ and φ→a
0
γ as well as the ratio φ→f
0
γ/a
0
γ are also given. 相似文献
14.
The concept of ‘D-Differentiation’, which, in the context of smooth manifolds, generalises Lie and covariant differentiation, is extended to
R
∞ -supermanifolds under the name of ‘Super D-Differentiation’. This is done by defining new (non-linear) mappings, called ‘μ-mappings’ and by relating their non-linearity to the Leibniz rule that a derivation must satisfy when it acts on a tensor
product. The resulting axiomatics, which is basis-independent and coordinate-free, is then expressed in a general basis (not
necessarily holonomic). Super Lie and Super covariant differentiation are, amongst others, special cases of Super D-Differentiation. In particular, the transformation rules for the connection coefficients and the commutation coefficients
of non-holonomic bases are obtained. These special cases are found to be in agreement with the DeWitt Super covariant and
Super Lie derivatives.
相似文献
15.
The transverse momentum distributions of W± and Z0 are predicted at RHIC and LHC. A resummation formalism with power corrections to the renormalization group equations is used. Shadowing effects are discussed and found to be unimportant at RHIC, but important for LHC. We study the enhancement of power corrections due to multiple scattering in nuclear collisions and numerically illustrate the weak effects of the dependence on the nuclear mass. 相似文献
16.
Peng-Ming Zhang Xi-Guo Lee Shao-Feng Wu 《International Journal of Theoretical Physics》2007,46(12):3234-3241
We investigate the solitons in the CP
N
model in terms of the decomposition of gauge potential. Based on the φ-mapping topological current theory, the charge and position of solitons is determined by the properties of the typical component.
Furthermore, the motion and the bifurcation of multi-soliton is discussed. And the knotted solitons in high dimension is explored
also. 相似文献
17.
Julia Lindberg Peter Saetre Seiji Nishino Emmanuel Mignot Elena Jazin 《BMC neuroscience》2007,8(1):34
Background
Narcolepsy causes dramatic behavioral alterations in both humans and dogs, with excessive sleepiness and cataplexy triggered by emotional stimuli. Deficiencies in the hypocretin system are well established as the origin of the condition; both from studies in humans who lack the hypocretin ligand (HCRT) and in dogs with a mutation in hypocretin receptor 2 (HCRTR2). However, little is known about molecular alterations downstream of the hypocretin signals. 相似文献18.
Marek Mac Tomasz Uchacz Tomasz Wróbel Andrzej Danel Ewa Kulig 《Journal of fluorescence》2010,20(2):525-532
Novel fluorescing dyes 1,3,4-triphenyl-6-(1,4,7,10-tetraoxa-13-aza-cyclopentadec-13-ylmethyl)-1H-pyrazolo[3,4-b]quinoline (K1) and 2-[(2-hydroxyethyl)-(1,3,4-triphenyl-1H-pyrazolo[3,4-b]quinolin-6-ylmethyl)-amino]ethanol (L1) have been synthesized and investigated by the means of steady state and time-resolved fluorescence techniques. These compounds
act as sensors for the fluorescence detection of small inorganic cations (lithium, sodium, barium, magnesium and calcium)
in solvents of different polarities (THF and acetonitrile). The mechanism, which allows application of these compounds as
sensors, is an electron transfer from the electro-donative part of molecule to the acceptor part (fluorophore), which is retarded
upon complexation of the electro-donative part by inorganic cations. We found that crown ether-containing compound is very
sensitive to the addition of any investigated ions but amino alcohol-containing one exhibits better selectivity to the addition
of two-valued cations. Two kinds of the complexes (LM+ and L2M+) were found in the investigated systems. In addition, the dyes may be used as fluorescence indicators in solvents of lower
polarity like tetrahydrofuran. 相似文献
19.
David Kerr 《Communications in Mathematical Physics》2003,232(3):501-534
We introduce notions of dimension and dynamical entropy for unital C
*
-algebras ``metrized' by means of , which are complex-scalar versions of the Lip-norms constitutive of Rieffel's compact quantum metric spaces. Our examples
involve the UHF algebras and noncommutative tori. In particular we show that the entropy of a noncommutative toral automorphism with respect to the
canonical coincides with the topological entropy of its commutative analogue.
Received: 13 February 2002 / Accepted: 20 August 2002 Published online: 22 November 2002 相似文献
20.
We investigate the Hawking radiation and greybody factor for a scalar field on the background of the black holes in the theory
of the non-minimal R
β
F
2-coupled electromagnetic fields to gravity. For different asymptotic structures caused by the real power number β, we find that the influences of the real power number on the Hawking radiation and greybody factor are different. We also
show that the different coupling constant also affects the Hawking radiation and greybody factor. 相似文献