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991.
992.
M. P.?Westig R.?Engels K.?Grigoryev M.?Mikirtytchiants F.?Rathmann H.?Paetz gen. Schieck G.?Schug A.?Vasilyev H.?Str?her 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,57(1):27-32
A Lamb-shift polarimeter, which has been built for a fast
determination of the polarization of protons and deuterons of an
atomic-beam source and which is frequently used in the ANKE
experiment at COSY-Jülich, is shown to be an excellent device for
atomic-spectroscopy measurements of metastable hydrogen isotopes. It
is demonstrated that magnetic and electric dipole transitions in
hydrogen can be measured as a function of the external magnetic
field, giving access to the full Breit-Rabi diagram for the
22S1/2 and the 22P1/2 states. This will allow the study
of hyperfine structure, g factors and the classical Lamb shift.
Although the data are not yet competitive with state-of-the-art
measurements, the potential of the method is enormous, including a
possible application to anti-hydrogen spectroscopy. 相似文献
993.
994.
In this paper we discuss how partial knowledge of the density of states for a model can be used to give good approximations
of the energy distributions in a given temperature range. From these distributions one can then obtain the statistical moments
corresponding to e.g. the internal energy and the specific heat. These questions have gained interest apropos of several recent
methods for estimating the density of states of spin models. As a worked example we finally apply these methods to the 3-state
Potts model for cubic lattices of linear order up to 128. We give estimates of e.g. latent heat and critical temperature,
as well as the micro-canonical properties of interest.
相似文献
995.
S. S. Aplesnin L. I. Ryabinkina O. B. Romanova V. V. Sokolov A. Yu. Pichugin A. I. Galyas O. F. Demidenko G. I. Makovetski? K. I. Yanushkevich 《Physics of the Solid State》2009,51(4):698-701
The temperature dependences of the specific magnetization σ and the electrical resistivity ρ of Me
x
Mn1 − x
S single crystals (Me= Co, Gd; x= 0.05) have been studied in the temperature range 80 K < T < 1000 K. The samples under study have revealed the presence of a spontaneous magnetic moment below the Néel temperature
(T
N) and ferromagnetic clusters in Gd0.05Mn0.95S in the temperature range 146 K < T < 680 K. Substitution of gadolinium for manganese initiates a transition from p-type to n-type conduction. The change in the conduction type is accompanied by an increase in the electrical resistivity at 300 K by
approximately one order of magnitude and, accordingly, by a decrease in the activation energy. The magnetic and electrical
properties of the crystals under study have been interpreted in terms of the cluster model with temperature-dependent ferromagnetic
exchange and an electron localized in this cluster.
Original Russian Text ? S.S. Aplesnin, L.I. Ryabinkina, O.B. Romanova, V.V. Sokolov, A.Yu. Pichugin, A.I. Galyas, O.F. Demidenko,
G.I. Makovetskiĭ, K.I. Yanushkevich, 2009, published in Fizika Tverdogo Tela, 2009, Vol. 51, No. 4, pp. 661–664. 相似文献
996.
Karol Sza?owski Tadeusz BalcerzakAndrej Bobák 《Journal of magnetism and magnetic materials》2011,323(15):2095-2102
The thermodynamics of a site-diluted ferromagnetic Heisenberg model for spin S=1/2 with interaction anisotropy in spin space is investigated. The study is aimed at presenting the magnetocaloric properties of such a model, including the entropy and temperature changes in magnetization/demagnetization processes, generalized Grüneisen ratio as well as the quantities characterizing the efficiency of magnetic cooling cycles. The results are obtained using pair approximation (PA) method and extensively compared with the molecular field approximation (MFA) calculations. The importance of interaction anisotropy and site-dilution is discussed. The inadequacy of the MFA approach (even on the qualitative level) is found for selected quantities, while PA provides the results which are consistent with the experimentally observed behavior. 相似文献
997.
G.R. Berdiyorov M.V. Miloševi?F.M. Peeters 《Physica C: Superconductivity and its Applications》2010,470(19):946-948
Using the time-dependent Ginzburg–Landau formalism, we study the dynamic properties of a submicron superconducting loop in applied current and in presence of a perpendicular magnetic field. The resistive state of the sample is caused by the motion of kinematic vortex–antivortex pairs. Vortices and antivortices move in opposite directions to each other, perpendicularly to the applied drive, and the periodic creation and annihilation of such pairs results in periodic oscillations of the voltage across the sample. The dynamics of these kinematic pairs is strongly influenced by the applied magnetic field, which for high fields leads to the flow of just vortices. Kinematic vortices can be temporarily pinned inside the loop with observable trace in the voltage vs. time characteristics. 相似文献
998.
A simple and convenient route is presented for the preparation of regio- and stereoisomers of novel azepane β-amino esters, starting from bicyclic β-lactam isomers. The synthetic procedure consists of dihydroxylation of the olefinic bond of the alicyclic amino esters, followed by NaIO4-mediated cleavage of the diol intermediate and reductive ring closure, which furnishes novel regioisomeric 5-aminoazepane-4-carboxylate and 3-aminoazepane-4-carboxylates. This method also allows the preparation of amino esters with an azepane skeleton in enantiomerically pure form. 相似文献
999.
Various aspects of the C-metric representing two rotating charged black holes accelerated in opposite directions are summarized
and its limits are considered. A particular attention is paid to the special-relativistic limit in which the electromagnetic
field becomes the “magic field” of two oppositely accelerated rotating charged relativistic discs. When the acceleration vanishes
the usual electromagnetic magic field of the Kerr–Newman black hole with gravitational constant set to zero arises. Properties
of the accelerated discs and the fields produced are studied and illustrated graphically. The charges at the rim of the accelerated
discs move along spiral trajectories with the speed of light. If the magic field has some deeper connection with the field
of the Dirac electron, as is sometimes conjectured because of the same gyromagnetic ratio, the “accelerating magic field”
represents the electromagnetic field of a uniformly accelerated spinning electron. It generalizes the classical Born’s solution
for two uniformly accelerated monopole charges. 相似文献
1000.
In this Letter, the dynamic plane elasticity problems of 2D quasicrystals is considered. By use of the Fourier transform and matrix transformations the system is reduced to uncoupled ordinary differential equations. Fourier images of Green's functions for dynamic plane elasticity problems of 2D dodecagonal, pentagonal and decagonal quasicrystals are obtained explicitly by the suggested method. 相似文献