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1.
G. Lindenblatt H. Wenz W. Behmenburg 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,13(3):329-336
By selective optical excitation of collision pairs and observation of the reemitted fluorescence information is obtained on
the role of the molecular channels involved in inelelastic collisions. As an example case we have studied experimentally the
Li( 3
D
→ 3
P) excitation transfer in Li(3D)X systems with X
=
Ne, Ar by means of the optical collision process Li
(2
P
) +
X
+
h
ν→
LiX
(3
D
Λ) →
Li
(3
P
, 3
D
) +
X where LiX
(3
D
Λ) collision molecules dissociate into Li(3P, 3D) atoms following laser excitation h
ν of Li
(2
P
) +
X pairs. For this purpose we measured the Li 3P/3D population ratio by the fluorescence from these levels as function of the
laser detuning Δν from the Li(2P-3D) transition and the rare gas pressure, and determined from this the 3P/3D excitation ratio B
(Δν) for single collision conditions. The experiments were performed using two step cw laser excitation of gaseous mixtures Li
+
X at temperatures around 600 K in the detuning range |Δν| ? 100 cm-1. The B
(Δν) profiles obtained display strong blue-red wing asymmetries both for Li
*
Ne and Li
*
Ar. This reflects different dissociation probabilities from the 3
D
Σ or 3
D
(Π,Δ) states that are initially prepared by blue wing or red wing excitation, respectively. The results are qualitatively discussed
in terms of new ab initio potentials for the two systems.
Received 23 February 2000 and Received in final form 5 July 2000 相似文献
2.
P. Descouvemont 《The European Physical Journal A - Hadrons and Nuclei》2001,12(4):413-419
The 9Be and 9B nuclei are investigated in a microscopic three-cluster model involving α + α +
n (or α + α +
p) configurations. The 8Be (0
+
, 2
+
) +
n and 5He (3/2
-
, 1/2
-
) + α (or mirror) channels are included by taking account of the unstable nature of 8Be and 5He. Spectroscopic properties of 9Be and 9B are analyzed. We show that the 5He + α configurations cannot be neglected to derive accurate results. The 9Be(γ,αα)n photodisintegration cross-section is shown to be mainly determined by 8Be + n channels at low energies, but 5He + α channels become important beyond E
γ≈ 4 MeV.
Received: 7 September 2001 / Accepted: 19 November 2001 相似文献
3.
D. E. Feldman 《JETP Letters》1999,70(2):135-140
The random field and random anisotropy N-vector models are studied with the functional renormalization group in 4−ε dimensions. The random anisotropy Heisenberg (N=3) model has a phase with an infinite correlation length at low temperatures and weak disorder. The correlation function
of the magnetization obeys a power law 〈m(r
1)m(r
2)〉∼|r
1−r
2|− 0.62ε. The magnetic susceptibility diverges at low fields as χ∼H
−1+0.15ε. In the random field N-vector model the correlation length is finite at arbitrarily weak disorder for any N>3.
Pis’ma Zh. éksp. Teor. Fiz. 70, No. 2, 130–135 (25 July 1999)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献
4.
The nonadiabatic corrections to the self-energy part Σs(q, ω) of the phonon Green’s function are studied for various values of the phonon vectors q resulting from electron-phonon interactions. It is shown that the long-range electron-electron Coulomb interaction has no
direct influence on these effects, aside from a possible renormalization of the corresponding constants. The electronic response
functions and Σs(q, ω) are calculated for arbitrary vectors qand energy ω in the BCS approximation. The results obtained for q=0 agree with previously obtained results. It is shown that for large wave numbers q, vertex corrections are negligible and Σs(q, ω) possesses a logarithmic singularity at ω=2Δ, where Δ is the superconducting gap. It is also shown that in systems with nesting, Σs(Q, ω) (where Q is the nesting vector) possesses a square-root singularity at ω=2Δ, i.e., exactly of the same type as at q=0. The results are used to explain the recently published experimental data on phonon anomalies, observed in nickel borocarbides
in the superconducting state, at large q. It is shown, specifically, that in these systems nesting must be taken into account in order to account for the emergence
of a narrow additional line in the phonon spectral function S(q, ω)≈−π
−1 Im D
s
(q, ω), where D
s
(q, ω) is the phonon Green’s function, at temperatures T<T
c
.
Zh. éksp. Teor. Fiz. 115, 1799–1817 (May 1999) 相似文献
5.
N. Shramchenko F. Dénoyer 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(1):51-59
A detailed investigation of the Fourier space of several Al-Pd-Mn samples with composition Al-72.6 at. %, Pd-22.9 at. %, Mn-4.5
at. % is reported. In the phase diagram of the Al-Pd-Mn ternary alloy, this composition corresponds to the so-called ξ' phase which was described as an icosahedral quasicrystalline approximant. By re-examining the Fourier space by means of
X-ray diffraction (powder patterns and single crystal precession patterns), complex structures in close relation with the
ξ'-phase have been observed. These long-range order complex structures are described as resulting from a periodic perturbation
of the ξ' structure along the c direction. Two states with periodicities c
(3 + τ) and c
(5 + τ) have been observed in this study (τ: golden mean). Structural models based on periodic arrangements of “defects” layers separating layers of phase are proposed. These two states are certainly intermediate states between the phase and the metastable decagonal quasicrystalline phase.
Received 11 April 2002 / Received in final form 24 June 2002 Published online 17 September 2002 相似文献
6.
L. I. Buravov 《Russian Physics Journal》2009,52(1):25-32
Masses of a number of elementary particles are calculated on the basis of the model suggested in [1] with the use of one parameter. In this model, an electron is considered as an electric cloud enclosed inside an elastic
lepton shell, electron neutrino ν
е
is considered as an elastic lepton shell contracted to a minimal size, and muon, pion and kaon are considered as resonators
for quanta of virtual neutrinos excited inside the elastic lepton shell. The number and type of these quanta are determined
from the decay scheme for μ, π, and K: 2 for the muon (ν
е
and ), 3 for the pion (ν
е
,
ν
μ, and ), and at least 21 for the kaon. The model allows mass ratios approximating the experimental data for these particles to be
obtained for the first time, with the ratio of μ and е masses equal to (6πℏс/е
2)2/3 ≅ 188, the ratio of π
0 and μ masses equal to (3/2)2/3, and the ratio of K
0 and π
0
equal masses to 72/3. The calculated e, μ
,
π
0, and K
0 masses are in the 0.547:105.707:134.963:493.87 (MeV) ratios (normalized by the neutral pion mass). This is in good agreement
with the available experimental data. The mass ν
е
(≅ 0.02 eV) is also estimated in this model, and the variety of K-meson decay schemes is naturally explained as a result of the variety of excited intrinsic neutrino field structures with
the same energy.
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 23–29, January, 2009. 相似文献
7.
8.
The correlation of the local density of states 〈ρɛ(r
1)ρɛ + ω(r
2)〉 in quasi-one-dimensional disordered wires in a magnetic field is calculated under the assumption that |r
1 − r
2| is much smaller than the localization length. This amounts to finding the zero mode of the transfer-matrix Hamiltonian for
the supersymmetric σ model, which is done exactly by mapping to the three-dimensional Coulomb problem. Both the regimes of
level repulsion and level attraction are obtained, depending on |r
1 − r
2|. We demonstrate that the correlations of different eigenfunctions in the quasi-one-dimensional and strictly one-dimensional
cases are dissimilar.
The text was submitted by the authors in English. 相似文献
9.
N. A. Silant’ev 《Journal of Experimental and Theoretical Physics》1999,89(1):45-55
In this paper the procedure of large-scale averaging of the magnetic-field diffusion equation with the α-term curlα(r,t)B(r,t) is used to show that a nonuniform distribution of the turbulent helicity fluctuations (more precisely, the fluctuations
of the coefficient α) with a zero average value gives rise to large-scale amplification of the initial magnetic field. A detailed study is carried
out of the dependence of the resulting large-scale α effect on the characteristics of the correlator 〈〈α(r, t)α(r″,t″)〉〉 in a rotating medium with a nonuniform distribution of the angular velocity ω=ω(ρ,z) (ρ is the distance for the rotation axis z). The effect of helicity fluctuations and the diffusion coefficient on the turbulent diffusion process is also investigated.
Zh. éksp. Teor. Fiz. 116, 85–104 (July 1999) 相似文献
10.
I. Kolokolov V. Lebedev M. Stepanov 《Journal of Experimental and Theoretical Physics》1999,88(3):506-516
We consider advection of a passive scalar θ(t,r) by an incompressible large-scale turbulent flow. In the framework of the Kraichnan model all PDF’s (probability distribution
functions) for the single-point statistics of θ and for the passive scalar difference θ(r
1)−θ(r
2) (for separations r
1−r
2 lying in the convective interval) are found.
Zh. éksp. Teor. Fiz. 115, 920–939 (March 1999)
Published in English in the original Russian journal. Reproduced here with stylistic changes by the Translation Editor. 相似文献
11.
Pablo A. Ferrari Beat M. Niederhauser Eugene A. Pechersky 《Journal of statistical physics》2007,128(5):1159-1176
We consider the Harmonic crystal, a measure on
with Hamiltonian H(x)=∑
i,j
J
i,j
(x(i)−x(j))2+h∑
i
(x(i)−d(i))2, where x, d are configurations, x(i), d(i)∈ℝ, i,j∈ℤ
d
. The configuration d is given and considered as observations. The ‘couplings’ J
i,j
are finite range. We use a version of the harness process to explicitly construct the unique infinite volume measure at finite
temperature and to find the unique ground state configuration m corresponding to the Hamiltonian. 相似文献
12.
Wen-Zhong Zhu Qiu-Yue Lin Mei Lu Rui-Ding Hu Xiao-Liang Zheng Jian-Ping Cheng Yun-Yun Wang 《Journal of fluorescence》2009,19(5):857-866
Three novel complexes [Nd(L)(NO3)(H2O)2]·NO3·2H2O (HL1 = N-pyrimidine norcantharidin acylamide acid, C12H13N3O4; HL2 = N-pyridine norcantharidin acylamide acid, C13H14N2O4; HL3 = N-phenyl norcantharidin acylamide acid, C14H15NO4) were synthesized. HL1, HL2 and HL3 are the ligand of complex(1), complex(2) and complex(3), respectively. Their structures were characterized by elemental analysis, conductivity measurement, infrared spectra and
thermogravimetric analysis. The DNA-binding properties of the complexes have been investigated by fluorescence spectroscopy
and viscosity measurements. The results suggest that the complexes can bind to DNA by partial intercalation. The liner Stern-Volmer
quenching constant Ksq values are 3.3(±0.21)(1), 1.7(±0.19)(2) and 0.9(±0.04)(3), respectively. Complex (1) and (2) have been found to cleave pBR322 plasmid DNA at physiological pH and temperature. The test of antiproliferation activity
indicates that complex(1) has strong antiproliferative ability against the SMMC7721 (IC50 = 131.7 ± 23.4 μmol·L−1) and A549 (IC50 = 128.4 ± 19.9 μmol·L−1) cell lines. The inhibition rates of complex(2) (IC50 = 86.3 ± 11.3 μmol·L−1) are much higher than that of NCTD (IC50 = 115.5 ± 9.5 μmol·L−1) and HL2 (111.0 ± 5.7 μmol·L−1) against SMMC7721 cell lines. 相似文献
13.
E. Cappelluti C. Grimaldi L. Pietronero S. Strässler G.A. Ummarino 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,21(3):383-391
In this paper, through an exhaustive analysis within the Migdal-Eliashberg theory, we show the incompatibility of experimental
data of Rb3C60 with the basic assumptions of the standard theory of superconductivity. For different models of the electron-phonon spectral
function α
2
F
(Ω) we solve numerically the Eliashberg equations to find which values of the electron-phonon coupling λ, of the logarithmic phonon frequency
and of the Coulomb pseudopotential μ
*
reproduce the experimental data of Rb3C60. We find that the solutions are essentially independent of the particular shape of α
2
F
(Ω) and that, to explain the experimental data of Rb3C60, one has to resort to extremely large couplings: λ = 3.0±0.8. This results differs from the usual partial analyses reported up to now and we claim that this value exceeds the maximum
allowed λ compatible with the crystal lattice stability. Moreover, we show quantitatively that the obtained values of λ and
strongly violate Migdal's theorem and consequently are incompatible with the Migdal-Eliashberg theory. One has therefore
to consider the generalization of the theory of superconductivity in the nonadiabatic regime to account for the experimental
properties of fullerides.
Received 30 March 2001 相似文献
14.
It is shown that the degeneracy of the noncanonical Poisson bracket operating on the space of solenoidal vector fields that
arises due to the freezing-in of the curl of the velocity [E. A. Kuznetsov and A. V. Mikhailov, Phys. Lett. A 77, 37 (1980)] is lifted when the vorticity Ω is represented in terms of vortex lines. This representation makes it possible
to integrate the equation of motion of the vorticity for a system with the Hamiltonian H=∫∣Ω∣d
r.
Pis’ma Zh. éksp. Teor. Fiz. 67, No. 12, 1015–1020 (25 June 1998) 相似文献
15.
G. Fabritius G. Flik J. Golczewski D. Herlach G. Jünemann M. Krenke K. Maier A. P. Pathak H. Rempp A. Seeger W. Sigle E. Widmann D. W. Cooke 《Hyperfine Interactions》1986,31(1-4):229-234
By means of π+/μ+ channelling, positive pions (π+) implanted intoTa, Mo, andW are investigated up to high temperatures. A striking observation is that the channelling effect disappears in a rather narrow
temperature interval centred at 0.26 (Ta) to 0.51 (W) of the melting temperature. From studies of π+ trapping by oxygen atoms inTa estimates for the low-temperature π+ diffusivity inTa [D
π(23K)=1.4·10−10±0.3 m2s−1,D
π(47K)=5.7·10−10±0.3 m2s−1] as well as for the binding enthalpy of π+ to 0 atoms (H
B=7·10−2 eV) have been obtained. The diffusion data are in reasonable agreement with the theory of phonon-assisted tunnelling. 相似文献
16.
Many structures in nature are invariant under the transformation pair, (p,r)→(b
r,−p/b), where b is some scale factor. Born’s reciprocity hypothesis affirms that this invariance extends to the entire Hamiltonian and equations
of motion. We investigate this idea for atomic physics and galactic motion, where one is basically dealing with a 1/r potential and the observations are very accurate, so as to determine the scale b≡mΩ. We find that an Ω∼1.5×10−15 s−1 has essentially no effect on atomic physics but might possibly offer an explanation for galactic rotation, without invoking
dark matter. 相似文献
17.
M. Celasco R. Eggenhöffner 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,23(4):415-419
A dynamical percolative model explaining the universality of 1/
f
γ
noise is reported. Exponents γ ranging from 0 to 2 are obtained under the hypothesis that noise originates from random switching events between two ON-OFF
states in elemental parts (switchers) of a physical system. The usual noise behaviour with γ very close to 1 in an arbitrarily wide frequency range is obtained assuming a statistical distribution of switcher relaxation
time τ proportional to τ
-1
, as in McWhorter's model. The impact of these results with respect to recent self-organised criticality models is discussed.
Received 6 November 2000 and Received in final form 22 May 2001 相似文献
18.
P. Boubert P. Vervisch 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,17(1):43-48
Excitation of carbon monoxide molecules has been carried out in a cold cell and in a low-pressure plasma jet using an ArF
narrow-band excimer laser. The different excitation models are discussed and the relevance of atomic carbon absorption into
the laser cavities is pointed out. Excitation spectra of Cameron bands have been obtained in a room-temperature cell and compared
with calculated spectra. A value of the constant σ related to the interaction strength between a
3
Π(
v
= 2) state and its neighbouring singlet states is derived: 0≤σ≤0.05. The fluorescence spectrum following broad band excitation of CO has been observed both in UV and visible. Similar experiments
carried out in a high enthalpy flow have allowed to point out the presence of a
3
Π metastable carbon monoxide. A method for relative measurements of this species concentration is proposed.
Received 9 April 2001 and Received in final form 13 June 2001 相似文献
19.
A. I. Alekseev 《Journal of Experimental and Theoretical Physics》1997,84(1):35-50
The properties of the density matrix and the multipole moments arising in oriented and aligned atoms with zero nuclear spin
through the interaction with strong resonant ultrashort pulses with wave vector k
0 and circular or linear polarization have been found. Calculations have been made for the time-dependent light-induced magnetization
μ(t′) of a gas of pre-oriented and prealigned atoms following the passage of a weak resonant elliptically polarized pulse with
frequency ω and wave vector k collinear with k
0. It is shown that for oriented atoms, μ(t′) is an even function of the detuning from resonance, ω-ω
ba, and can be split into two terms whose directions are a consequence of symmetry and are determined by the vectors k
0 and k as well as by the direction of rotation of the electric fields corresponding to the pulses. For aligned atoms the vector
μ(t′) is collinear with k, and the first term is an even function of ω-ω
ba. However, the second term is an odd function of ω-ω
ba and reverses direction when the sign of ω-ω
ba changes, as well as when the orientation of the axes of the polarization ellipse is changed. It is shown that if a series
of weak linearly polarized pulses pass through the gas, the light-induced magnetization of the oriented and aligned gas atoms
can be decomposed into three factors: the first determines the direction and is a consequence of the symmetry; the second
(with the dimensions of magnetic moment) depends on the characteristics of the resonant transitions; and the third is a universal
function of t′ and ω-ω
ba that does not depend on the underlying characteristics of the resonant transition. These vector factors and the universal
functions are in principle different for oriented and aligned atoms.
Zh. éksp. Teor. Fiz. 111, 63–92 (January 1997) 相似文献
20.
An explicit solution is obtained for the four-wave mixing ω4=ω1−ω 2+ω3 of two strong fields E
1, E
3 and two weak fields E
2, E
4 in a four-level system with large Doppler broadening. Resonance of the intensity dependence of the mixing coefficient is
found around equal Rabi frequencies, E
1·d
1=E
3·d
3, where d
1,3 are the dipole moments of the corresponding transitions. The effect is interpreted as a crossing of quasi-energy levels.
Up to 6 peaks appear in the dependence of the conversion coefficient on the detuning of the probe field E
2. The unexpected additional pair of peaks is a consequence of averaging over velocities. The results permit interpretation
of the saturation behavior found in recent experiments on mixing in sodium vapor.
Pis’ma Zh. éksp. Teor. Fiz. 66, No. 12, 777–782 (25 December 1997)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献