127La转动带及带终止

组态相关推转壳模型 Nilsson势研究了 C.M.Parry组最近用 EUROBALL谱仪观测到的 12 7La高自旋态结构 .实验上观测的 12 7La的宇称和辛量子数为 (π,α) =(+,- 1 /2 )的带自旋达到(83/2 ) h.理论计算结果表明该带可能具有组态 π(h11/2 ) 2 ν(h11/2 ) 6.并且几乎达到该带的带终止理论预言值 I=47.5h.该带的形变在 I≤ 40 h内处于正常形变区 (ε2 ≈ 0 .2 2 ,γ≈ 0°) ,随着角动量的增加 γ值逐渐增加 ,直到 γ=60°时带终止. HJ4/9]The configuration dependent shell correction approach with cranked Nilsson potential is employed for explaining the experimental high spin spectra in 127 La. The experimental high spin band with parity and signature (+, -1/2) consists of two parts with a crossing around I =20 . It is most like to have the configuration [02, 6], π (h 11/2 ) 2 ν (h 11/2 ) 6 and almost reaching the maximum angular momentum at I =47.5 . It is in normal deformation region with ...     

转动谱的若干理论及其对超形变带的研究

简述了若干转动谱理论及其对超形变带的应用 ,并用 Bohr- Mottelson的 I(I+1 )展开公式分析了 A=1 90区超形变带的性质和指定了它们的能级自旋 ,用 Harris的ω2 展开公式 J(1) =2α+(4/3 )βω2 +(6 /5 )γω4分析了 A=1 5 0区 Tb和 Dy同位素 2 0条超形变带的性质 ,指定了它们的能级自旋 .对于首次发现的152 Dy(1 )超形变带 ,带首自旋指定为 2 6 h,与实验结果更加符合. The recent developments of rotational spectral theories and its application to superdeformed bands were briefly reviewed. The superdeformed bands in A ≈190 region were analyzed and the spins of energy level were determined by the least square fitting experimental transition energy with the formula of Bohr Mottelson’s I(I+1) expansions. The superdeformed bands in A ≈150 region were analyzed by using the kinematic moments of inertia formula J (1) =2α+(4/3)βω 2+(6/5)γω 4 in...     

正常形变带[521]1/2的ΔI=1颤动

系统分析了A≈ 170区正常形变带 [5 2 1]1/ 2 - 中的ΔI =1颤动现象 .根据旋称伙伴带的跃迁能量提取Δ2 Eγ(I) =[Eγ(I) +Eγ(I- 2 ) ]/ 2 -Eγ(I - 1)值 ,表现出旋称相关的规则上下颤动 .其颤动幅度在低自旋端约为 5 0keV ,而后随自旋而增大或减小 ,大体呈抛物线形 .利用改进的ab公式 ,提取了相关的脱耦合系数 .运用Nilsson波函数 ,探讨了原子核集体哈密顿量中高阶微扰项的可能形式 .     

Nuclear inelastic scattering study of a dinuclear iron(II) complex showing a direct spin transition

The results of the nuclear inelastic scattering (NIS)/nuclear resonance vibrational spectroscopy (NRVS) for the powder spectra of dimeric [Fe ₂L₅(NCS) ₄] (L = N-salicylidene-4-amino-1,2,4-triazole) complex are presented. This system is spin crossover (SCO) material tagged with a fluorophore that can sense or “feel” the SCO signal ripping through the molecular network and thereby providing an opportunity to register the SCO transition. The spectra have been measured for the low-spin and high-spin phases of the complex. The high-spin isomer reveals one broad band above 200 cm ^?1, while the low-spin one displays two intense bands in the range from 390 to 430 cm ^?1, accompanied by a number of weaker bands below this area and one at ca. 490 cm ^?1. A normal coordinate analysis based on density functional calculations yields the assignment of the spin marker bands to particular molecular modes. In addition the vibrational contribution to the spin transition has been estimated     

Energy Staggering in Ground Bands of 232Th and 236,238U Nuclei Using the Interacting Vector Boson Model

The ΔI=2 and ΔI=4 staggering parameters of transition energies E_γ for normally deformed positive parity ground bands in ²³²Th and ^236,238U nuclei are studied in framework of the symplectic extension of the interacting vector boson model. The model parameters are obtained from the fitting procedure between the calculated excitation energies and the corresponding experimental ones. The staggering parameters represent the finite difference approximations to higher order derivatives dⁿE_γ/d Iⁿ of the γ -ray transition energies in a ΔI=2 and ΔI=4 bands, which yielding multipoint formulae. The first order derivative (two-point formula) provides us with information about the dynamical moment of inertia. The staggering oscillation for the fourth order derivative (five-point formula) is about 0.5 KeV and is even larger than that in superdeformed bands. The quite similarity in dynamical moments of inertia of the isotopes ^236,238U up to high spin states indicate that the phenomenon of identical bands is not restricted to superdeformed bands.     

Re-discussion of the Spin Assignments of the Superdeformed Bands in A≈190 Region (Ⅱ) Odd Superdeformed Nuclei

The influence of the I=1 staggering and the fluctuation in observed γ-tyanstion energies on the spin assignments of superdeformed bands is taken into account properly. An improved approach for removing the fluctuations from the observed y transition energies is proposed. The smoothed transition energies are fitted by the ah expression or its modification to assign the spins of the superdeformed bands in the odd-A nuclei in A≈190 region. The assigned spins for some superdeformed bands are different from those given in other approaches.     

Band head spin assignment of Tl isotopes of superdeformed rotational bands

The Variable Moment of Inertia (VMI) model is proposed for the assignment of band head spin of super deformed (SD) rotational bands, which in turn is helpful in the spin prediction of SD bands. The moment of inertia and stiffness parameter (C), were calculated by fitting the proposed transition energies. The calculated transition energies are highly dependent on the prescribed spins. The calculated and observed transition energies agree well when an accurate band head spin (I ₀) is assigned. The results are in good agreement with other theoretical results reported in literature. In this paper, we have reported the band head spin value 16 rotational band of super deformed Tl isotopes.     

Mott transition in kagomé lattice Hubbard model

We investigate the Mott transition in the kagomé lattice Hubbard model using a cluster extension of dynamical mean field theory. The calculation of the double occupancy, the density of states, and the static and dynamical spin correlation functions demonstrates that the system undergoes the first-order Mott transition at the Hubbard interaction U/W approximately 1.4 (W:bandwidth). In the metallic phase close to the Mott transition, we find the strong renormalization of three distinct bands, giving rise to the formation of heavy quasiparticles with strong frustrated interactions. It is elucidated that the quasiparticle states exhibit anomalous behavior in the temperature-dependent spin correlation functions.     

Identification of Rotational Band in Doubly Odd 170Ta

High spin states in ¹⁷⁰Ta have been studied via ¹⁵⁹Tb(¹⁶O,5nγ)¹⁷⁰Ta reaction through excitation functions, K X-γ and γ-γ-t coincidence measurements. Three rotational bands have been identified among which one coupled band and an unfavored δI=2 E2 transition sequence are newly found in this work. The possible quasiparticle configurations of these bands are discussed. Received: 7 November 1997     

Superfluid-to-normal phase transition in superdeformed bands

A semiclassically exact solution for the second inertial parameter B is found for the superfluid and normal phases. An interpolation between these limiting values shows that B changes sign in the transition region at the spin I _c that is critical for the rotational spectrum. A superfluid-to-normal transition reveals itself in a specific variation of B versus the spin I. Experimental data show the existence of a transition for superdeformed bands in the A～80, 130, and 150 mass regions and for some bands characterized by a normal deformation. A transition to the normal phase explains the extreme regularity of superdeformed bands.     

Identification of Bandhead Spin and Identical Bands for Odd-A Nuclei in $A\sim190$ Superdeformed Mass Region

The dynamical moment of inertia is estimated with its even-power expansion of the rotational frequency and in accordance we determine the intermediate spins of the superdeformed (SD) rotational bands. Using Marquardt method of nonlinear least-squares routines, we determine the expansion coefficients by fitting the proposed dynamical moment of inertia with its recent experimental data of the SD nuclei in the A=190 mass region. The comparison between our theoretical and available experimental data for the dynamic moment of inertia and spin shows good agreements. Also, we have calculated the static moment of inertia at three alternative values of spin. The value of spin at which the two moments of inertia are nearly equals is to be regarded as a bandhead spin of the corresponding band. These studies are carried out for eighteen bands of odd-A nuclei of the superdeformed region 190, namely ¹⁸⁹Hg(b1), ¹⁹¹Hg(b1, b2, b3, b4), ¹⁹³Hg(b2, b3, b5), ¹⁹⁵Hg(b1, b2, b3, b4), ¹⁹³Tl(b1, b2, b3, b5), ¹⁸⁹Tl(b1), and ¹⁹⁷Bi(b1). We also notice the occurrence of identical SD bands with near identical transition energies among the considered SD bands.     

Enhancing sensitivity of quadrupolar nuclei in solid-state NMR with multiple rotor assisted population transfers

Rotor-assisted population transfer (RAPT) was developed as a method for enhancing MAS NMR sensitivity of quadrupolar nuclei by transferring polarization associated with satellite transitions to the central m=12-->-12 transition. After a single RAPT transfer, there still remains polarization in the satellite transitions that can be transferred to the central transition. This polarization is available without having to wait for the spin system to return to thermal equilibrium. We describe a new RAPT scheme that uses the remaining polarization of the satellites to obtain a further enhancement of the central transition by performing RAPT-enhanced experiments multiple times before waiting for re-equilibration of the spin system. For 27Al (I=5/2) in albite we obtain a multiple RAPT enhancement of 3.02, a 48% increase over single RAPT. For 93Nb (I=9/2) in NaNbO(3) we obtain a multiple RAPT enhancement of 5.76, an 89% increase over single RAPT. We also describe a data processing procedure for obtaining the maximum possible signal-to-noise ratio.     

Band Structure in Doubly Odd 170Ta

High spin states in ¹⁷⁰Ta have been studied via ¹⁵⁹Tb(¹⁶O,5nγ)¹⁷⁰Ta reaction at 105MeV.Three rotational bands are observed,among which one coupled band and an unfavored ΔI=2 E2 squence are newly found in this owrk.The possible quasiparticle configurations of these bands are discussed.     

Nitrogen and Boron substitutional doped zigzag silicene nanoribbons: Ab initio investigation

We performed a spin polarized density-function theory study of the stabilities, electronic and magnetic properties of zigzag silicene nanoribbons (ZSiNRs) substitutionally doped with a single N or B atom located at various sites ranging from edge to center of the ribbon. From minimization of the formation energy, it is found that the substitutional doping is favorable at edge of the ribbon. A single N or B atom substitution one edge Si atom of ZSiNRs can greatly suppress the spin-polarizations of the impurity atom site and its vicinity region, and leads to a transition from antiferromagnetic (AFM) state to ferromagnetic (FM) state, which is attributed to the splitting of the original spin degenerate edge bands. A single N atom doped ZSiNRs still keep semiconductor property but a single B atom doped ZSiNRs exhibit a half-metallic character. Our results reveal that substitution doped ZSiNRs have potential applications in Si-based nanoelectronics, such as field effect transisitors (FETs), negative differential resistance (NDR) and spin filter (SF) devices.     

Novel Quadruple Fluorescence Properties of Two Benzoylthiourea Isomers

Two benzoylthiourea isomers, N-2-flurobenzoy-N'-4- (N,N-dimethyl)amidophenylthiourea (2FBDAPT) and N-4-fluro-benzoy-N'-4- (N,N-dimethyl)amidophenylthiourea (4FBDAPT) were determined by fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) and X-ray diffraction. It was found that intra- and intermolecular hydrogen bonds played an important role in determining their conformations. Electronic spectra of the two compounds were investigated by UV absorption and steady-state fluorescence methods. The intermolecular hydrogen bond between the title compounds and methanol molecules caused the long wavelength absorption bands in methanol to weaken and vanish indeed. Quadruple fluorescence bands in ultraviolet and visible region were observed in the studied solvents upon the variable excitation wavelength. As same as Azumaya's suggestions for benzanilide (BA), F4 fluorescence bands with the maximum wavelength (λ(max)) between 546?nm and 622?nm were characteristic of TICT fluorescence. F3 bands of λ(max) from 434?nm to 483?nm were explained by the ESIPT model of the S1 state of the thiol tautomer to the S1 state of the keto tautomer. The new proposition was that F2 bands with λ(max) at about 365?nm were attributed to ESIPT from the S1 state of the thiol tautomer to the S0 state of the enol tautomer. And F1 fluorescence emissions with λ(max) at about 310?nm originated from the local S1 transitions of the enol tautomer. All experimental results were supported by MP2, CASSCF and CASPT2 quantum chemical calculations.     

A=135核区N=79的同中异位素高自旋结构研究

摘要: 对清华大学在束γ谱实验组近年来在A=135缺中子核区N=79的同中异位素 135Ba, 137Ce和 139Nd的高自旋态实验研究进行了介绍。 实验是在中国原子能科学研究院HI 13串列加速器上用在束γ的实验技术、 分别通过重离子核反应 130Te(9Be, 4n), 124Sn(18O, 5n), 128Te(16O, 5n)进行的。 实验结果扩展了这3个核的高自旋态能级纲图。 研究表明, 这3个核的低自旋态结构均起源于 νh-111/2空穴与其偶偶核芯的耦合。 用粒子 转子模型对其结构进行了计算, 得到这3个核的形变参量γ值均稍大于30°, 为偏向于扁椭的三轴形变, 从而可看出Ba, Ce和Nd 3个同位素链在低自旋态下由长椭边到扁椭边的形状转变都发生在中子数N=77—79之间。 对于中等自旋态下一些能级的组态进行了指定与系统学比较。 在高自旋态下, 在 137Ce中发现一条γ≈－60°的扁椭形变带, 在 139Nd中则发现3条这样的扁椭形变带, 对这些扁椭形变带的起源及结构特性进行了讨论。 The progress of research on the high spin states at N=79 isotopes 135Ba, 137Ce and 139Nd in A=135 neutron deficient region by the research group of Tsinghua University has been reviewed. The experiments were carried out by using in beam γ ray spectroscopy technology and heavy ion nuclear reactions 130Te(9Be, 4n), 124Sn(18O, 5n) and 128Te(16O, 5n) at China Institute of Atomic Energy (CIAE). The high spin level schemes of these nuclei have been expanded. The results indicate that the lower spin states of these nuclei originated from νh-111/2 hole state coupling with the neighboring even even nucleus cores. All the deformation parameters γ values of these three isotones are larger than 30°, which indicates that they have triaxial deformation with oblate side. The prolate oblate transition in Ba, Ce and Nd isotopic chains indeed happens between N=77 and N=79. Through systematical comparison with the neighboring isotones, the configurations for some middle spin state levels have been assigned. At the high spin states, one oblate band in 137Ce and three ones in 139Nd with γ≈ -60° were discovered. The origination and structural character of these oblate bands have been discussed.     

Microscopic study of electromagnetic properties and band spectra of neutron deficient ~(133,135,137)Sm

A microscopic high spin study of neutron deficient and normally deformed ~(133,135,137)Sm has been carried out in projected shell model framework.The theoretical results have been obtained for the spins,parities and energy values of yrast and excited bands.Besides this,the band spectra,band head energies,moment of inertia and electromagnetic transition strengths are also Predicted in these isotoPes.The calculations successfully give a deeper understanding of the mechanism of the formation of yrast and excited bands from the single and multi-quasi particle configurations.The results on moment of inertia predict an alignment of a pair of protons in the proton(1 h_(11/2))~2 orbitals in the yrast ground state bands of ~(133-137)Sm due to the crossing of one quasiparticle bands by multi-quasiparticle bands at higher spins.The discussion in the present work is based on the deformed single particle scheme.Any future experimental confirmation or refutation of our predictions will be a valuable information which can help to understand the deformed single particle structure in these odd mass neutron deficient ~(133-137)Sm.     

Mott physics, sign structure, ground state wavefunction, and high-T c superconductivity

In this article I give a pedagogical illustration of why the essential problem of high-T _c superconductivity in the cuprates is about how an antiferromagnetically ordered state can be turned into a short-range state by doping. I will start with half-filling where the antiferromagnetic ground state is accurately described by the Liang-Doucot-Anderson (LDA) wavefunction. Here the effect of the Fermi statistics becomes completely irrelevant due to the no double occupancy constraint. Upon doping, the statistical signs reemerge, albeit much reduced as compared to the original Fermi statistical signs. By precisely incorporating this altered statistical sign structure at finite doping, the LDA ground state can be recast into a short-range antiferromagnetic state. Superconducting phase coherence arises after the spin correlations become short-ranged, and the superconducting phase transition is controlled by spin excitations. I will stress that the pseudogap phenomenon naturally emerges as a crossover between the antiferromagnetic and superconducting phases. As a characteristic of non Fermi liquid, the mutual statistical interaction between the spin and charge degrees of freedom will reach a maximum in a high-temperature ??strange metal phase?? of the doped Mott insulator.     

面心立方格子上Ising自旋Ⅰ(1)的反铁磁性——配分函数的级数展开法

本文采用与文献[1]完全相类似的方法作出一般化Ising模型s=1在面心立方格子(fcc)上最近邻相互作用的反铁磁系统的统计理论,即用Pad近似式处理配分函数的高、低温幂级数有限项展开式,得出其反铁磁-顺磁转变为一阶相变。T_c=1.33J/k,小于(1/2)相应的相变点。文中算出了相关的热力学量如内能、潜热、熵、比热、长程和短程序参量,以及磁化率等。值得指出的是:(1)fcc上反铁磁-顺磁相变属于一阶,这是由格子密堆积的拓扑特征所决定,与s的大小无关;(2)T_c(s)随s的增加而缓慢地下降。 关键词：