共查询到20条相似文献,搜索用时 31 毫秒
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罗亦孝 J.H.Hamilton J.O.Rasmussen A.V.Ramayya C.Goodin A.V.Daniel N.J.Stone 朱胜江 J.K.Hwang 刘少华 C.J.Beyer 李科 H.L.Crowell D.Almehed S.Frauendorf A.Covello V.Dimitrov 张敬业 车兴来 姜卓 D.Fong A.Gelberg I.Stefanescu A.Gargano E.F.Jones P.M.Gore I.Y.Lee G.M.Ter-Akopian M.A.Stoyer R.Donangelo 马文超 J.D.Cole J.Kormicki 张学谦 S.C.Wu J.Gilat T.N.Ginter S.J.Asztalos 《原子核物理评论》2010,27(4):363-389
使用Gammasphere多探测器系统对252Cf裂变源瞬发γ射线进行γ-γ-γ和γ-γ(θ)符合测量,A~100(Z~40,N56)丰中子核区关于形状过渡、形状共存和形状突变的深入研究获得了新的进展。奇-Z核的系统研究揭示了从Z=39(Y)同位素的轴对称大四极形变到Z=43(Tc),44(Ru)和45(Rh)同位素中具有中等四极形变之大三轴形变的过渡。Nb(Z=41)同位素具有过渡核的特征。根据邻近同位素和同中素带交叉信息的系统性及推转壳模型(CSM)计算,Tc和Rh偶-N同位素中观察到的带交叉产生于一对h11/2中子的转动顺排。首次观察到100Nb(Z=41,N=59)的高自旋能级纲图和形变态,从而证实了100Nb中的形状共存,并确认,在Nb同位素链上,基态形状突变发生于N=58(球形)到N=59(大形变);而在Sr(Z=38),Y(Z=39)和Zr(Z=40)各同位素链上,基态形状突变均发生于N=59(球形)到N=60(大形变)。100Nb具有大形变基态,同现有理论预言相矛盾,其大形变的基态及转动带所具有的很大的和不规则的转动惯量具有重要的理论意义。对奇-质子Cs(Z=55)和La(Z=57)丰中子同位素八极激发的详细研究,发现了141,143,144Cs同位素链上电二极矩D0随中子数增加而减小的急剧变化,此前在145,147La中观察到的电二极矩D0的较缓和的减小似乎亦很陡地下延至148La。在Cs和La同位素中观察到的电二极矩D0的急剧下降很可能同偶-质子核146Ba和224Ra中观察到的电二极矩D0的急剧下降相类似,后者已获反射非对称平均场壳修正理论的成功解释。实验证明,141Cs具有很大电二极矩D0。141Cs和142Xe中观测到的很大的电二极矩D0和仅在141Cs中观察到的电二极矩D0的simplex量子数相关性需要进一步的理论研究。根据转动频率比值ω-(I)/ω+(I)的检定,同Xe同位素一样,认定Cs同位素中包括号143Cs的八极激发为八极振动,而在La同位素中存在八极形变。 相似文献
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W. Urban T. Rzaca-Urban N. Schulz J.L. Durell W.R. Phillips A.G. Smith B.J. Varley I. Ahmad 《The European Physical Journal A - Hadrons and Nuclei》2003,16(3):303-307
Excited levels in 140Xe and 142Xe nuclei, populated in the spontaneous fission of 248Cm, were studied by means of prompt γ-ray spectroscopy, using EUROGAM2 array. We report the first observation of an octupole
band in 142Xe and extend the octupole band in 140Xe. Level schemes of 140Xe and 142Xe obtained in this work show patterns characteristic of ocupole-vibrational bands. Properties of octupole bands in Xe isotopes
indicate that octupole correlations in these nuclei are lower than in the corresponding Ba nuclei. The electric dipole moment
of 142Xe was found to be larger than in other Xe isotopes, contrary to theoretical predictions. This may be due to the special role
of the N = 88 neutron number.
Received: 18 November 2002 / Accepted: 15 December 2002 / Published online: 25 February 2003
RID="a"
ID="a"e-mail: urban@fuw.edu.pl
Communicated by D. Schwalm 相似文献
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The potential energy surfaces of the even-even~(68-92)Se,~(112-150)Ba,and~(208-230)Ra isotopes are calculated using the macroscopic-microscopic method in a multidimensional space{α_(λ,μ)}including quadrupole(λ=2,μ=0,2)and octupole(λ=3,μ=0,1,2,3)degrees of freedom.The calculated results show that the even-even isotopes~(92)Se,~(112,114,144-150)Ba and~(220-228)Ra can exhibit the coexistence of triaxial and octupole deformations,thereby leading to simultaneous chiral and reflected symmetry breaking.Therefore,chirality-parity quartet bands are expected in these and their neighboring odd-A/odd-odd nuclei. 相似文献
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H. Baltzer K. Freitag C. Günther P. Herzog J. Manns U. Müller R. Paulsen P. Sevenich T. Weber B. Will 《Zeitschrift für Physik A Hadrons and Nuclei》1995,352(1):47-67
The electron-capture decay of228Pa to levels in228Th has been studied using mass-separated sources and high-resolutionγ-ray and conversion-electron spectroscopy. A level at 979.5 keV is assigned as 2+ member of a second excited Kπ=0+ band, with the 0+ band head at 938.6 keV. The 2+ and 3+ members of a second excited Kπ=2+ band at 1153.5 and 1200.5 keV, which decay by strongE0 transitions to the 969 keVγ-vibrational band, are confirmed. In addition we tentatively propose a Kπ=1+ band at 944 keV. The Kπ=0?, 1? and 2? members of the octupole quadruplet are confirmed, and theγ decay of these levels is analysed in an approach, in which the mixing of the octupole bands by the Coriolis interaction is taken into account. It is suggested that octupole correlations might be important for theE1 transition moments. A total of 29 levels is observed between ~1.4 and ~2.0 MeV, for which the nuclear structure, and the possible assignment to rotational bands, is unclear. 相似文献
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G. V. Benemanskaya S. N. Timoshnev S. V. Ivanov G. E. Frank-Kamenetskaya D. E. Marchenko G. N. Iluridze 《Journal of Experimental and Theoretical Physics》2014,118(4):600-610
The electronic structure of the n-GaN(0001) and Al x Ga1 ? x N(0001) (x = 0.16, 0.42) surfaces and the Ba/n-GaN and Ba/AlGaN interfaces is subjected to in situ photoemission investigations in the submonolayer Ba coverage range. The photoemission spectra of the valence band and the spectra of the surface states and the core 3d level of Ga, the 2p level of Al, and the 4d and 5p levels of Ba are studied during synchrotron excitation in the photon energy range 50–400 eV. A spectrum of the surface states in Al x Ga1 ? x N (x = 0.16, 0.42) is found. The electronic structure of the surface and the near-surface region is found to undergo substantial changes during the formation of the Ba/n-GaN and Ba/AlGaN interfaces. The effect of narrowing the photoemission spectrum in the valence band region from 10 to 2 eV is detected, and surface eigenstates are suppressed. The Ba adsorption is found to induce the appearance of a new photoemission peak in the bandgap at the Fermi level in the Ba/n-GaN and Ba/n-Al0.16Ga0.84N interfaces. The nature of this peak is found to be related to the creation of an accumulation layer due to a change in the near-surface potential and enriching band bending. The energy parameters of the potential well of the accumulation layer are shown to be controlled by the Ba coverage. 相似文献
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Qian T Wang XP Jin WC Zhang P Richard P Xu G Dai X Fang Z Guo JG Chen XL Ding H 《Physical review letters》2011,106(18):187001
We have performed an angle-resolved photoemission spectroscopy study of the new iron-based superconductor K(0.8)Fe(1.7)Se(2) (T(c)~30 K). Clear band dispersion is observed with the overall bandwidth renormalized by a factor of 2.5 compared to our local density approximation calculations, indicating relatively strong correlation effects. Only an electronlike band crosses the Fermi energy, forming a nearly circular Fermi surface (FS) at M (π, 0). The holelike band at Γ sinks ~90 meV below the Fermi energy, with an indirect band gap of 30 meV, to the bottom of the electronlike band. The observed FS topology in this superconductor favors (π, π) inter-FS scattering between the electronlike FSs at the M points, in sharp contrast to other iron-based superconductors which favor (π, 0) inter-FS scattering between holelike and electronlike FSs. 相似文献
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A. M. Bizzeti-Sona P. G. Bizzeti F. Banci Buonamici D. Bazzacco S. Lunardi F. Soramel G. Lo Bianco N. Molho G. De Angelis J. Simpson 《Zeitschrift für Physik A Hadrons and Nuclei》1990,337(2):235-236
High-spin states up to I=22? have been observed for the first time in the odd-odd nucleus142Eu above the 8? β+ -decaying isomer. A new isomer of mean life τm=9.0± 0.6 ns and Jπ=8+ has been identified. The low energy part of the level scheme is interpreted in terms of single-particle excitations in the 2d5/2 and h11/2 orbitals and of the N=80 core excitations. 相似文献
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D. Nosek R. K. Sheline P. C. Sood J. Kvasil 《Zeitschrift für Physik A Hadrons and Nuclei》1992,344(3):277-283
Microscopic structures of the proposed parity doublet bands in the odd-proton Z=61151Pm and Z=63153, 155Eu nuclei are examined using the quasiparticle phonon nuclear model Hamiltonian including the residual pairing and multipole-multipole interactions. Octupole correlations between intrinsic nonrotational states are studied to check the suggested assignments of parity doublet partners in these nuclei. We conclude significant octupole correlations between a pair ofK π = 1/2± doublets in each of these nuclei, with somewhat weaker correlations betweenK π = 3/2± bands in both the Eu isotopes. No octupole connection between the lowestK π = 5/2± bands is found; however, significant octupole collectivity, built on the low-lying 5/2? bands, is predicted in the higher-lying 5/2+ bands which contain the 5/2+ [402] fragmented strength. 相似文献
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I. Sankowska Ch. Droste E. Grodner T. Morek J. Srebrny A. A. Pasternak J. Kownacki P. Napiorkowski S. G. Rohoziński M. Kowalczyk M. Kisieliński R. Kaczarowski E. Ruchowska 《The European Physical Journal A - Hadrons and Nuclei》2008,37(2):169-175
Lifetimes of the yrast levels with spins I π = 23/2? to 39/2? in 129La produced via the 120Sn(14N, 5n) reaction at a beam energy of 77MeV have been measured by the Doppler shift attenuation method. The properties of the studied levels belonging to the πh11/2 band were compared with the theoretical predictions obtained in the framework of the core quasi-particle coupling model. It is suggested that the rigid-rotor model used to describe the cores is too simplified as the even-even nuclei from the A ~ 130 region are susceptible to shape deformation. Reasonable agreement was obtained with the phenomenological cores based on the experimental data of 128Ba. 相似文献
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介绍了通过测量重核裂变产生的瞬发γ谱方法,对围绕Z=56、N=88丰中子核区高自旋态八极形变的研究,并对Xe、Ba、Ce和La等丰中子核链的八极形变特性进行了讨Through study of the prompt γ rays in spontaneous fission, the octupole deformation in neutron rich Xe, Ba, Ce and La isotopes around Z =56, N =88 region was assigned. The properties of the octupole deformation in these nuclei were also discussed. 论. 相似文献
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在不同K覆盖度的W(100)面上吸附CO的Hel紫外光电子能谱研究表明:α和β态的CO由于K的影响,吸附状态发生改变,与CO分子态(α态)有关的5σ/1π分子轨道能级随K覆盖度的增加,结合能位置从8.6eV移到9.3eV,反映K出现后,衬底对α-CO分子反施的增强。在与CO分解态(β态)有关的谱峰位置上(结合能为5.5eV)出现两个离散的谱峰,一个在6.0eV左右,另一个在5.2eV左右。其中结合能在5.2eV左右的谱峰强度随K的覆盖度增加而增大,它的能量位置与O在K覆盖的W(100)面上吸附时的能级位置
关键词: 相似文献
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A multiple wave vector (Q) reconstruction of the Fermi surface is shown to yield a profoundly different electronic structure to that characteristic of single wave vector reconstruction, despite their proximity in energy. We consider the specific case in which ordering is generated by Q(x)=[2πa,0] and Q(y)=[0,2πb] (in which a=b=1/4)-similar to those identified in neutron diffraction and scanning tunneling microscopy experiments-and more generally show that an isolated pocket adjacent to the nodal point k(nodal)=[±π/2,±π/2] is a protected feature of such a multiple-Q model, potentially corresponding to the nodal "Fermi arcs" observed in photoemission and the small size of the electronic heat capacity found in high magnetic fields-importantly, containing electron carriers which can yield negative Hall and Seebeck coefficients observed in high magnetic fields. 相似文献
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M. Piiparinen P. Kleinheinz S. Lunardi M. Ogawa G. de Angelis F. Soramel W. Meczynski J. Blomqvist 《Zeitschrift für Physik A Hadrons and Nuclei》1990,337(4):387-406
Through (α, 4n) and (τ, 3n) reactions the high-spin states in the two-neutron nucleus148Gd were populated up toI π=21? at 7.2 MeV, including numerous states above the yrast line. The148Gd energy spectrum is interpreted in terms of the spherical shell model. Identification of the (νf 7/2 i 1 3/2)10? state gives the νi 13/2 single particle energy free of octupole admixtures as 2.1(1) MeV. Eight high-spin states between 1.2 and 3.7 MeV were identified as the couplings of the two valence-particles to the146Gd octupole phonon, and three above-lying levels are assigned as double-octupole excitations including a 12+ state which decays by anE3-E3 stretched cascade. All these octupole levels can be quantitatively predicted from the one-particle x phonon spectrum of147Gd. The high-spin states above 3 MeV are four-quasiparticle excitations ofπ +1 π ?1 ν 2 andπ 2 ν 2 type and their energies are in good accord with shell model estimates. 相似文献
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We report the electronic structure of the Au-intercalated graphene/Ni(111) surface using angle-resolved photoemission spectroscopy and low energy electron diffraction. The graphene/Ni(111) shows no Dirac cone near the Fermi level and a relatively broad C 1s core level spectrum probably due to the broken sublattice symmetry in the graphene on the Ni(111) substrate. When Au atoms are intercalated between them, the characteristic Dirac cone is completely recovered near the Fermi level and the C 1s spectrum becomes sharper with the appearance of a 10?×?10 superstructure. The fully Au-intercalated graphene/Ni(111) surface shows a p-type character with a hole pocket of ~0.034?Å?1 diameter at the Fermi level. When the surface is doped with Na and K, a clear energy gap of ~0.4?eV is visible irrespective of alkali metal. 相似文献
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Nakayama K Sato T Richard P Kawahara T Sekiba Y Qian T Chen GF Luo JL Wang NL Ding H Takahashi T 《Physical review letters》2010,105(19):197001
We have performed angle-resolved photoemission spectroscopy of the iron-chalcogenide superconductor Fe1.03Te0.7Se0.3 to investigate the electronic structure relevant to superconductivity. We observed a holelike Fermi surface (FS) and an electronlike FS at the Brillouin zone center and corner, respectively, which are nearly nested by the Q~(π,π) wave vector. We do not find evidence for the nesting instability with Q~(π+δ,0) reminiscent of the antiferromagnetic order in the parent compound Fe1+yTe. We have observed an isotropic superconducting (SC) gap along the holelike FS with the gap size Δ of ~4 meV (2Δ/kBTc ~ 7), demonstrating the strong-coupling superconductivity. The observed similarity of low-energy electronic excitations between iron-chalcogenides and iron-arsenides strongly suggests that common interactions which involve Q~(π,π) scattering are responsible for the SC pairing. 相似文献
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By the first-principles calculations, we studied the structure, electronic and magnetic properties of LaOMnSe. The band structure and Fermi surface of LaOMnSe are very similar to those of LaOFeAs, where there are three hole-like Fermi surfaces around Γ-point and two electron-like Fermi surfaces around M-point. The hole-like Fermi surfaces will strongly overlap with electron-like Fermi surfaces if they are shifted by the q vector (π,π,0). Such Fermi surfaces nesting will induce magnetic instability and spin density wave (SDW), which is similar to LaOFeAs. Because of so much similarity to LaOFeAs, LaOMnSe is expected to become superconductor with electron or hole doping. 相似文献
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通过第一性原理计算,我们研究了LaOMnSe的结构、电子性质和磁性质.我们发现LaOMnSe在11点附近存在三个类空穴费米面,在M点附近有两个类电子费米面.如果将类空穴费米面平移(π,π,O),则类空穴费米面就会和类电子费米面在很大程度上重叠,这种费米面嵌套将会导致磁不稳定性和自旋密度波(SI)、V),和LaOFeAs... 相似文献