共查询到20条相似文献,搜索用时 0 毫秒
1.
Cammarere D. Scheicher R. H. Briere T. M. Sahoo N. Das T. P. Pratt F. L. Nagamine K. 《Hyperfine Interactions》2001,136(3-8):759-762
Muon Spin Relaxation (μSR) experiments are currently being conducted on the important electron transfer molecule cytochrome
c (cyt c) with the goal to find out about microscopic details of the path the moving electron is taking. Simultaneously we
are using the Unrestricted Hartree–Fock Cluster Procedure to determine the trapping sites for muon (μ+) and muonium (Mu) in the heme unit of cyt c and the associated hyperfine interactions. For the trapping sites with the highest
binding energies for μ+, namely the nitrogen and the carbon of the pyrrole rings, we have used the available magnetic susceptibility data together
with our calculated hyperfine fields to predict the Knight-shifts. At room-temperature we found 88.4 ppm and 79.0 ppm for
the most attractive N- and adjacent C-site, respectively. At 150 K, these shifts increase to 172.7 ppm for the N-site and
153.7 ppm for the C-site.
This revised version was published online in September 2006 with corrections to the Cover Date. 相似文献
2.
R. H. Scheicher E. Torikai F. L. Pratt K. Nagamine T. P. Das 《Hyperfine Interactions》2004,158(1-4):53-57
Muon Spin Relaxation (μSR) experiments in A- and B-form DNA have shown evidence for an enhanced electron mobility in the more closely-packed A-form.
Besides dynamic effects (electronic diffusion) that could cause the observed difference in muon spin relaxation, one should
also carefully examine the difference in the strengths of the hyperfine interactions of the muon (μ
+) with the moving electron in the two forms of DNA, since this could contribute to the observed difference in the muon spin
relaxation rates as well. We have therefore investigated the (static) trapping properties of muon and muonium (μ
+
e
−) in A-form and B-form DNA from first-principles with the aim to understand how the different structural geometries of A-
and B-form DNA can influence the hyperfine interaction of trapped muonium. 相似文献
3.
Nobuhiro Yamanaka 《Hyperfine Interactions》2000,127(1-4):129-132
The Fermi contact parameter which represents hyperfine structure (hfs) has been accurately calculated for the ground state
of the 9Be+ ion in a previous paper. In the present paper, the calculated parameter is compared with a high precision measurement to
derive the hfs anomaly (the Bohr-Weisskopf effect), which is caused by nuclear magnetization distribution. The obtained hfs
anomaly shows a satisfactory agreement with the result of a nuclear shell model calculation.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
4.
S. G. Karshenboim V. G. Ivanov 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,19(1):13-23
We consider hyperfine splitting of 1s and, in part, of 2s levels in light hydrogen-like atoms: hydrogen, deuterium, tritium, helium-3 ion, muonium and positronium. We discuss present
status of precision theory and experiment for the hfs intervals. We pay a special attention to a specific difference, D
21 = 8E
hfs(2s) - E
hfs(1s), which is known experimentally for hydrogen, deuterium and 3
He
+ ion. The difference is weakly affected by the effects of the nuclear structure and thus may be calculated with a high accuracy.
We complete a calculation of the fourth order QED contributions to this difference and present here new results on corrections due to the nuclear effects. Our theoretical
predictions appear to be in a fair agreement with available experimental data. Comparison of the experimental data with our
examination of D21 allows to test the state-dependent sector of theory of the hfs separation of the 1s and 2s levels in the light hydrogen-like atoms up to 10-8.
Received 22 September 2001 相似文献
5.
H. V. Klapdor-Kleingrothaus H. Päs U. Sarkar 《The European Physical Journal A - Hadrons and Nuclei》2000,8(4):577-580
We discuss violations of CPT and quantum mechanics due to interactions of neutrinos with space-time quantum foam. Neutrinoless
double beta decay and oscillations of neutrinos from astrophysical sources (supernovae, active galactic nuclei) are analysed.
It is found that the propagation distance is the crucial quantity entering any bounds on EHNS parameters. Thus, while the
bounds from neutrinoless double beta decay are not significant, the data of the supernova 1987a imply a bound being several
orders of magnitude more stringent than the ones known from the literature. Even more stringent limits may be obtained from
the investigation of neutrino oscillations from active galactic nuclei sources, which have an impressive potential for the
search of quantum foam interactions in the neutrino sector.
Received: 5 June 2000 / Accepted: 12 July 2000 相似文献
6.
Y.P. Gangrsky D.V. Karaivanov K.P. Marinova B.N. Markov L.M. Melnikova G.V. Mishinsky S.G. Zemlyanoi V.I. Zhemenik 《The European Physical Journal A - Hadrons and Nuclei》1998,3(4):313-318
The hyperfine structure of the D2 optical line in 22Na and 23Na has been investigated using high resolution laser spectroscopy of a well-collimated atomic beam. The hyperfine splitting
constants A and B for the excited 3p 2P3/2 level for both investigated sodium isotopes have been obtained. They are as follows: A(22) = 7.31(4) MHz, B(22) = 4.71(28)
MHz, A(23) = 18.572(24) MHz, B(23) = 2.723(55) MHz. With this data, using the high precision MCHF calculations for the electric
field gradient at the nucleus, the electric quadrupole moment of 22Na has been deduced: Qs(22) =+0.185(11) b. The sign of Qs(22), determined for the first time, indicates a prolate nuclear deformation. A precise value of the isotope shift 22,23Na in the D2 line has also been obtained.
Received: 26 February 1998 / Revised version: 25 June 1998 相似文献
7.
A. Korgul H. Mach B. Fogelberg W. Urban W. Kurcewicz T. Rzaca-Urban P. Hoff H. Gausemel J. Galy J.L. Durell W.R. Phillips A.G. Smith B.J. Varley N. Schulz I. Ahmad L.R. Morss M. Górska V.I. Isakov K.I. Erokhina J. Blomqvist F. Andreozzi F. Coraggio A. Covello A. Gargano 《The European Physical Journal A - Hadrons and Nuclei》2002,15(1-2):181-184
Excited states in the 134Sb nucleus, populated in the β--decay of 134Sn, have been studied at the mass separator OSIRIS. The 134Sn activity was produced via fast neutron-induced fission of 238U target. A main result was the discovery of a very low-lying first-excited state of 134Sb, at 13keV, which has led to a strong revision of the level scheme. The new results are compared with different theoretical
calculations and with the known data for the analogous neutron and proton two-particle nucleus in the 208Pb region. On the basis of this comparison, the energy of the ( πg
7/2νf
7/2)7- isomer is estimated to be about 250keV, some 100keV lower than previously reported.
Received: 21 March 2002 / Accepted: 16 May 2002 / Published online: 31 October 2002
RID="a"
ID="a"e-mail: anovak@fuw.edu.pl 相似文献
8.
V. M. Nadutov T. Ericsson S. G. Kosintsev S. M. Bugaychuk Ye. O. Svystunov H. Annersten 《Hyperfine Interactions》2006,168(1-3):1023-1027
F.C.C. Fe–30.3%Ni and Fe–30.5%Ni–1.5%C (wt.%) alloys were studied by means of Mössbauer spectroscopy in external magnetic field B ext?=?2.5, 5, 7 T parallel to the gamma-beam. It is shown that distribution of effective magnetic field in the alloys is broad and that carbon expands the range of B eff. The external magnetic field increases B eff in the Fe–Ni alloy and decreases it more evidently in the Fe–Ni–C alloy. Antiferromagnetic spin coupling along the ferromagnetic component is proposed to explain data. 相似文献
9.
L. Petit A. Svane W.M. Temmerman Z. Szotek 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,25(2):139-146
The electronic and magnetic properties of Pu monopnictides and monochalcogenides, PuX (X = N, P, As, Sb, Bi, O, S, Se, Te, Po), are studied using the self-interaction-corrected local spin-density approximation. This approach allows for an integer number of f-states to be localized, while the remaining f-electron degrees of freedom are available for band formation. By varying the relative proportions of localized and delocalized
f-states, the energetically most favourable (groundstate) configuration can be established. We show that the experimental data
can be interpreted in terms of the coexistence of both localized and delocalized f-states.
Received 10 August 2001 相似文献
10.
O. Sorlin C. Donzaud F. Nowacki J.C. Angélique F. Azaiez C. Bourgeois V. Chiste Z. Dlouhy S. Grévy D. Guillemaud-Mueller F. Ibrahim K.-L Kratz M. Lewitowicz S.M. Lukyanov J. Mrasek Yu.-E. Penionzhkevich F. de Oliveira Santos B. Pfeiffer F. Pougheon A. Poves M.G. Saint-Laurent M. Stanoiu 《The European Physical Journal A - Hadrons and Nuclei》2003,16(1):55-61
The neutron-rich nuclei 23
60-63V have been produced at GANIL via interactions of a 61.8A·MeV 76Ge beam with a 58Ni target. Beta-decay to 24
60-63Cr has been investigated using combined β- and γ-ray spectroscopy. Half-lives of the 60-63V nuclei have been determined, and the existence of a beta-decay isomer in the 60V nucleus is strongly supported. The observation of low-energy 2+ states in 60Cr (646keV) and 62Cr (446keV) suggests that these isotopes are strongly deformed with β2 ∼ 0.3. This is confirmed by shell model calculations which show the dominant influence of the intruder g and d orbitals to obtain low 2+ energies in the neutron-rich Cr isotopes.
Received: 13 June 2002 / Accepted: 27 August 2002 / Published online: 17 January 2003
RID="a"
ID="a"e-mail: sorlin@ipno.in2p3.fr
Communicated by D. Guerreau 相似文献
11.
H. Arenhövel W. Leidemann E.L. Tomusiak 《The European Physical Journal A - Hadrons and Nuclei》2002,14(4):491-509
Formal expressions are derived for the multipole expansion of the structure functions of a general polarization observable
of exclusive electrodisintegration of the deuteron using a longitudinally polarized beam and/or an oriented target. This allows
one to exhibit explicitly the angular dependence of the structure functions by expanding them in terms of the small rotation
matrices d
j
m'm(θ), whose coefficients are given in terms of the electromagnetic multipole matrix elements. Furthermore, explicit expressions
for the coefficients of the angular distributions of the differential cross-section including multipoles up to L
max = 3 are listed in tabular form.
Received: 19 November 2002 / Accepted: 7 May 2002 相似文献
12.
P. Farkašovský 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,20(2):209-215
A new numerical method is used to study the ground-state properties of the spinless Falicov-Kimball model in one and two dimensions.
The resultant solutions are used to examine the phase diagram of the model as well as possibilities for valence and metal-insulator
transitions. In one dimension a comprehensive phase diagram of the model is presented. On the base of this phase diagram,
the complete picture of valence and metal-insulator transitions is discussed. In two dimensions the structure of ground-state
configurations is described for intermediate interactions between f and d electrons. In this region the phase separation and metal-insulator transitions are found at low f-electron concentrations. It is shown that valence transitions exhibit a staircase structure.
Received 20 October 2000 相似文献
13.
R. Zitzler Th. Pruschke R. Bulla 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,27(4):473-481
We discuss the ground state magnetic phase diagram of the Hubbard model off half filling within the dynamical mean-field theory.
The effective single-impurity Anderson model is solved by Wilson's numerical renormalization group calculations, adapted to
symmetry broken phases. We find a phase separated, antiferromagnetic state up to a critical doping for small and intermediate
values of U, but could not stabilize a Néel state for large U and finite doping. At very large U, the phase diagram exhibits an island with a ferromagnetic ground state. Spectral properties in the ordered phases are discussed.
Received 9 January 2002 Published online 25 June 2002 相似文献
14.
S.V. Dordevic D.N. Basov R.C. Dynes B. Ruzicka V. Vescoli L. Degiorgi H. Berger R. Gaál L. Forró E. Bucher 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,33(1):15-23
We present a comprehensive analysis of the optical constants of the two-dimensional dichalcogenide materials 2
H
-
TaSe
2
and 2
H
-
NbSe
2
, in an attempt to address the physics of two-dimensional correlated systems. The title compounds were studied over several
decades in frequency, from the far-infrared to the ultraviolet. Measurements with linearly polarized light have allowed us
to obtain both the in-plane and out-of-plane components of the conductivity tensor. Although the electromagnetic response
of dichalcogenides is strongly anisotropic, both the in-plane and out-of-plane components of the conductivity tensor share
many common features, including the presence of a well-defined metallic component, as well as a “mid-infrared band”. We discuss
the implications of these results in the context of the spectroscopic results of other classes of low-dimensional conductors
such as the high-temperature superconducting cuprates. In particular, the analysis of the redistribution of the spectral weight
as a function of temperature, as well as the behavior of the quasiparticles relaxation rate, points to significant distinctions
between the charge dynamics of dichalcogenides and other classes of low dimensional conductors.
Received 28 October 2002 / Received in final form 10 March 2003 Published online 23 May 2003
RID="a"
ID="a"e-mail: degiorgi@solid.phys.ethz.ch 相似文献
15.
M. Modugno C. Fort P. Maddaloni F. Minardi M. Inguscio 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,17(3):345-349
We have investigated the center-of-mass oscillations of a 87Rb Bose-Einstein condensate in an elongated magneto-static trap. We start from a trapped condensate and we transfer part of
the atoms to another trapped level, by applying a radio-frequency pulse. The new condensate is produced far from its equilibrium
position in the magnetic potential, and periodically collides with the parent condensate. We discuss how both the damping
and the frequency shift of the oscillations are affected by the mutual interaction between the two condensates, in a wide
range of trapping frequencies. The experimental data are compared with the prediction of a mean-field model.
Received 28 May 2001 相似文献
16.
S. Anantha Ramakrishna N. Kumar 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,23(4):515-519
We re-examine and correct an earlier derivation of the distribution of the Wigner phase delay time for wave reflection from
a long one-dimensional disordered conductor treated in the continuum limit. We then numerically compare the distributions
of the Wigner phase delay time and the dwell time, the latter being obtained by the use of an infinitesimal imaginary potential
as a clock, and investigate the effects of strong disorder and a periodic (discrete) lattice background. We find that the
two distributions coincide even for strong disorder, but only for energies well away from the band-edges.
Received 11 June 2001 and Received in final form 30 July 2001 相似文献
17.
R. Citro M. Marinaro 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,28(1):55-60
Within a strong-coupling perturbative approach, based on a Cumulant Expansion of the extended single-band Hubbard model, we
show that the on-shell inverse scattering time deviates from the normal Fermi-liquid behavior near the points of the Fermi
surface connected by the characteristic wave-vector of an incommensurate charge density wave. The violation of the Fermi liquid
behavior is associated with a square root behavior of the inverse quasiparticle lifetime in proximity of a stripe phase. Some
relevant features observed in ARPES experiments on Bi2212 are qualitatively reproduced.
Received 28 February 2002 / Received in final form 7 May 2002 Published online 9 July 2002 相似文献
18.
T. Beier H. Häffner N. Hermanspahn S. Djekic H.-J. Kluge W. Quint S. Stahl T. Valenzuela J. Verdú G. Werth 《The European Physical Journal A - Hadrons and Nuclei》2002,15(1-2):41-44
We describe a double-Penning-trap experiment suitable for testing QED in strong fields by determining the electronic g-factor of a single hydrogen-like ion in its ground state. Our measurements on 12C5 + reach a relative accuracy of 2×10-9, where the largest uncertainty results from the mass of the electron. Together with equally precise theoretical predictions
therefore, it is possible to evaluate a new value for the electron's mass. The possibilities to obtain other fundamental constants
and nuclear parameters are lined out.
Received: 21 March 2002 / Accepted: 16 May 2002 / Published online: 31 October 2002
RID="a"
ID="a"e-mail: t.beier@gsi.de 相似文献
19.
V. Rodrigues D. Ugarte 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):395-398
We have used high resolution transmission electron microscopy to determine the structure of gold nanowires generated by mechanical
stretching. Just before rupture, the contacts adopt only three possible atomic configurations, whose occurrence probabilities
and quantized conductance were subsequently estimated. These predictions have shown a remarkable agreement with conductance
measurements from a break junction operating in ultra-high-vacuum, corroborating the derived correlation between nanowire
atomic structure and conductance behavior.
Received 28 November 2000 相似文献
20.
J.V. Jovanović S.B. Vrhovac Z.Lj. Petrović 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,21(3):335-342
Transport properties of ion swarms in presence of Resonant Charge Transfer (RCT) collisions are studied using Momentum Transfer
Theory (MTT). It was shown that, not surprisingly, RCT collisions may be represented as a special case of elastic scattering.
Using the developed MTT we tested a previously available anisotropic set of cross-sections for Ar+Ar
+ collisions by making the comparisons with the available data for the transverse diffusion coefficient. We also developed
an anisotropic set of Ne+Ne
+ integral cross-sections based on the available data for mobility, longitudinal and transverse diffusion. Anisotropic sets
of cross-sections are needed for Monte Carlo simulations of ion transport and plasma models.
Received 16 June 2002 / Received in final form 2nd August 2002 Published online 24 September 2002
RID="a"
ID="a"e-mail: vrhovac@phy.bg.ac.yu
RID="b"
ID="b"e-mail: zoran@phy.bg.ac.yu 相似文献