Precise determination of the 2s(1/2)-2p(1/2) splitting in very heavy lithiumlike ions utilizing dielectronic recombination

The 2s(1/2)-2p(1/2) energy splittings DeltaE(L) of the lithiumlike ions 19779Au76+, 20882Pb79+, and 23892U89+ have been measured at the Experimental Storage Ring, utilizing low energy dielectronic recombination. The resonance energies in total 41 different 1s(2) 2p(1/2)nl(j(')) (n > or =20) autoionizing Rydberg states populated in the dielectronic capture process have been determined. The 2s(1/2)-->2p(1/2) excitation energies have been obtained by extrapolation of these resonance energies to the associated series limits n--> infinity. The combined analysis of the experimental data for all three ions yields DeltaE(L)=216.134(96) eV for Au76+, 230.650(81) eV for Pb79+, and 280.516(99) eV for U89+.     

LiⅠ等电子序列[(1s2p)3P,4d]2P0及 [(1s2s)1S,5p]2P0自电离态的计算

利用鞍点复转动及全实加关联的方法,计算了LiⅠ等电子序列[(1s2p)3P,4d]2P0及[(1s2s)1S,5p]2P0自电离态的能量和宽度.计算结果中包括相对论修正和质量极化修正.文中讨论了自电离宽度随核电荷数Z的变化关系,同时也讨论了精细结构分裂值及相对论修正随核电荷数Z的变化关系.     

Photoexcitation of a dipole-forbidden resonance in helium

We have observed photoexcitation of the dipole-forbidden 1s(2) 1S0-->2p(2) 1D2 resonance in helium by measuring the nondipolar forward-backward asymmetry of photoelectron angular distributions in the 2l2l(') autoionizing region. By exploiting the electric dipole-quadrupole interference in the excitation of both the 2s2p 1P1 and 2p(2) 1D2 levels, we have observed the quadrupole resonance in photoabsorption and extracted its Fano line shape parameters and the relative phase of the 1sEp and 1sEd continua. We find the quadrupole line profile index q(2) to be markedly different from theoretical expectations.     

Strong Relaxation and Correlation Effects on the 2p 53s–2p 6 Spectrum of Neutral Neon

Hyperfine Interactions - The effects of correlation and relaxation on the 2p 53s?1,3 P 1–2p 6?1 S 0 resonance and intercombination transitions of neutral neon have been studied...     

延迟和相关效应对Ne原子2p53s1,3P10-2p6 1S0跃迁的影响

利用多组态Dirac-Fock(MCDF)方法,系统地研究了延迟和相关效应对中性Ne原子2p53s1,3P01-2p61S0电偶极共振和复合跃迁的能量以及跃迁几率(寿命)的影响,给出了相应的跃迁能和辐射寿命,并与最新的实验观测和其他理论计算结果进行了比较.     

铁电体SrBi2Nb2O2电子能带结构的第一性原理研究

采用第一性原理的方法计算了SrBi₂Nb_2O.9（SBN）的顺电相、铁电相的电子结构.顺电相是间接带隙, 铁电相是直接带隙，它们的大小分别为1.57和2.23 eV.顺电相和铁电相的价带顶均主要来自于O₂p态的贡献.而顺电相和铁电相的导带底则分别来自Nb₄d态和Bi₆p态的贡献.计算表明SBN铁电相的低的漏电流与Bi 6p轨道有关.由顺电相到铁电相时，Nb₄d和O_{2 关键词： 顺电相 铁电相 态密度 电子能带结构}     

弛豫与关联效应对NII离子2s22p3s3P1—2s22p21D2与2s22p3s1P1—2s22p23P0,1,2自旋禁戒跃迁概率的影响

用多组态Dirac-Fock方法，并系统考虑相对论效应、电子关联、弛豫效应等重要贡献，计算了NII离子2s22p3s 3P1—2s22p21D2和2s22p3s 1P1—2s22p23P0,1,2自旋禁戒跃迁概率和振子强度-通过比较计算证实：弛豫和关联效应对禁戒跃迁概率的影响非常大，考虑了这些效应后，计算结果有显著的改善-由跃迁概率和振子强度的计算值推断，2s22p3s 3P1—2s22p21D2的谱线强度应该比原有的理论预言值小- 关键词： 跃迁概率 多组态Dirac-Fock方法     

Observation of Single-slope Quasistatic Wings of Laser Induced Collision Energy Transfer

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｌａｓｅｒ ｉｎｄｕｃｅｄｃｏｌｌｉｓｉｏｎｅｎｅｒｇｙｔｒａｎｓｆｅｒ(ＬＩＣＥＴ)ｉｓａｎｏｐｔｉｃａｌｐｈｅｎｏｍｅｎｏｎｉｎｖｏｌｖｉｎｇｔｈｅｓｉｍｕｌｔａｎｅｏｕｓｉｎｔｅｒａｃｔｉｏｎｓｏｆｂｏｔｈｔｈｅｌａｓｅｒｆｉｅｌｄａｎｄｃｏｌｌｉｓｉｏｎ[1～ 3 ] .ＴｈｉｓＬＩＣＥＴｒｅａｃｔｉｏｎｃａｎｂｅｗｒｉｔｔｅｎａｓ:Ａ Ｂ ｈΩ →Ａ Ｂ (1)Ｄｕｒｉｎｇｔｈｅｃｏｌｌｉｓｉｏｎｏｆａｔｏｍ Ａｗｉｔｈａｔｏｍ Ｂ ,ａｔｏｍＡｇｏｅｓｂａｃｋｔｏｇｒ…     

Quantum phase transitions in the itinerant ferromagnet ZrZn2

We report a study of the ferromagnetism of ZrZn2, the most promising material to exhibit ferromagnetic quantum criticality, at low temperatures T as a function of pressure p. We find that the ordered ferromagnetic moment disappears discontinuously at p(c)=16.5 kbar. Thus a tricritical point separates a line of first order ferromagnetic transitions from second order (continuous) transitions at higher temperature. We also identify two lines of transitions of the magnetization isotherms up to 12 T in the p-T plane where the derivative of the magnetization changes rapidly. These quantum phase transitions (QPT) establish a high sensitivity to local minima in the free energy in ZrZn2, thus strongly suggesting that QPT in itinerant ferromagnets are always first order.     

类铍离子N3+激发态的能量、振子强度和跃迁几率

利用多组态相互作用方法及Rayleigh-Ritz变分法,计算了类铍N3+ 基态(1s22s21S)和三个激发态(1s22s2p1P0, 1s22s2p3 P0, 1s22p23P)的能量,运用截断变分方法得到能量的改进量,包括了相对论能量和质量极化效应.计算了相关态的振子强度和辐射跃迁率.计算结果与其它理论和实验结果符合得很好.     

Observation of Single-slope Quasistatic Wings of Laser Induced Collision Energy Transfer

Three transitions of laser induced collision energy transfer from Eu (6s6p)8P5/2 to Sr (5s10s)1S0, Eu(6s6p)8P7/2 to Sr(5s9d)1D2 and Eu(6s6p)8Ps/2 to Sr(5s9d)1D2 have been observed in experiments. The relation between the breadth of spectral lines and the energy structures were analyzed experimentally and theoretically by two dipole-dipole interactions.     

用类氦双电子复合伴线诊断Ar等离子体电子温度

在电子密度约为ne=10 13 cm-3 条件下计算了类氦Ar的伴线 j(1s2 2 p2 P3 / 2 - 1s2 p2 2 D5/ 2 )与共振线w(1s2 1S0 - 1s2P1P1)的强度比 ,采用Hartree Fork Relativistic (HFR)方法计算了伴线因子和波长 ,从而得到伴线强度以及强度比。根据计算的相对强度比随温度的变化关系可以利用实验诊断电子温度     

Revalidation of the isobaric multiplet mass equation

We have determined the energy of the J(pi) = 1/2(+), T = 3/2 resonance in 32S(p,p) to be E(p) = 3374.7+/-0.8 keV. This disagrees with the previously accepted value of E(p) = 3370+/-1 keV by Abbondanno et al. [Nuovo Cimento 70A, 391 (1970)] and solves a problem raised by recent observations of unexpected deviations from the isobaric multiplet mass equation. This resonance is also important in calibrating the beta-delayed proton spectra from 33Ar and 32Ar, and our findings may modify previous conclusions.     

Isomers of OCS and their reaction with H2O on singlet potential energy surface

The isomers of the carbonyl sulfide (OCS) molecule are investigated in detail at CCSD(T)/cc-pVTZ//MP2/6-311++G(2d,2p) level of theory. One cyclic isomer was identified along with three different linear minima of the OCS molecule. Three interconversion transition states were also located between cyclic and linear forms of OCS. Among these four isomers, the singlet potential energy surface (PES) for the molecule–molecule reaction between the three most energetically favoured isomers of OCS and H₂O has been explored theoretically at the CCSD(T)/cc-pVTZ//MP2/6-311++G(2d,2p) level. This singlet PES comprises of three paths. Path 1 is the reaction of linear OCS molecule with water producing the major product P1 (CO₂?+?H₂S), minor product P2 (S?+?HCOOH) and two isomers via 14 minima and 15 transition states. The Path 2 is an isomerization process in which cyclic isomer of OCS reacts with water molecule via another initial barrierless aduct producing five isomers of the OCS–H₂O system through five interconversion transition states. The reaction of linear COS isomer with water is shown in Path 3. This path produces the radicals SH and COOH from another COS–H₂O complex via a transition state. Among these three products, the product P1 is energetically most favoured. The overall exothermicity of the product channels for the formation of major product P1 on PES is calculated to be about 10.60?kcal/mol possessing initial high entrance barriers of 45.48 and 55.47?kcal/mol in two possible pathways. As the process is favoured thermodynamically but not kinetically, the reaction is expected to be very slow.     

Measurement of the absolute energy level and hyperfine structure of the 87Rb 4D5/2 state

We have measured the absolute frequency of the excited state transition 5P(3/2)-4D(5/2) in a (87)Rb atom with a femtosecond frequency comb, utilizing the recently developed spectroscopic technique of the double resonance optical pumping method. The absolute energy level of the 4D(5/2) state is determined by measuring the absolute frequency of the 5S(1/2)-5P(3/2) transition simultaneously. The hyperfine structure constants of the 4D(5/2) state are obtained by using the measured frequency. The magnetic dipole constant, A, is determined to be (-16.747+/-0.010) MHz with an uncertainty reduced 60-fold compared with a previous result. The electric quadrupole constant, B, is determined, for what is to our knowledge the first time, to be (4.149+/-0.059) MHz.     

Evidence for the coexistence of an anisotropic superconducting gap and nonlocal effects in the nonmagnetic superconductor LuNi2B2C

A study of the dependence of the heat capacity C(p)(alpha) on the field angle in LuNi2B2C reveals an anomalous disorder effect. For pure samples, C(p)(alpha) exhibits a fourfold variation as the field H (alpha=0). A slightly disordered sample, however, develops anomalous secondary minima along <110> for mu(0)H>1 T, leading to an eightfold pattern at 2 K and 1.5 T. The anomalous pattern is discussed in terms of coexisting superconducting gap anisotropy and nonlocal effects.     

KⅧ—TbLⅣ离子3s3p 3P1—3s21S0 的自旋禁戒跃迁

在对KⅧ—TbLⅣ离子3s3p3P1能级结构的多组态相互作用理论HXR方法计算的基础上, 分析了各种效应对等电子序列离子能级结构的影响, 找出了能级沿等电子序列变化的规律性. 预测计算了KⅧ—TbLⅣ离子3s3p3P1的能级. 由此进一步计算了KⅧ—TbLⅣ离子自旋禁戒跃迁3s3p3P1—3s21S0的谱线波长、 振子强度和跃迁概率. We have calculated the energy levels of 3s3p3P1 for magnesium like sequence ions from KⅧ—TbLⅣ by HXR (Hartree Forck plus statistical exchange potential with relativistic corrections) method. With the important effects taken into account, we have made a systematic fit for the energy levels of the ions mentioned above. We predicted here the energy levels which have not been observed in experiments for ions from KⅧ to TbLⅣ.The wavelengths, oscillator strengths and probabilities of intercombination transitions 3s3p 3P1—3s21S0 are computed too.     

类锂离子C^3＋激发态（1s^2 2p）^2P光电离的计算

文中首次运用R—矩阵方法，在三态密耦近似下计算了类锂离子C^3 激发态(1s^2 2p)^2P光电离截面，主要给出了不同过程和不同分波的光电离截面。计算结果显示了光电离过程中非常丰富的Rydberg系列共振结构。     

Isomerization of C3H3NO isomers: ab initio study

The structures and isomerization process of C₃H₃NO species have been explored at the MP2/6–311++G(d,p) level of theory of the ab initio method. Eleven minima and four interconversion transition states have been identified. The zero-point vibrational energy corrections were made to predict reliable energies. We predict a five-membered ring-like structure to be the lowest energy isomer, which is 177.73?kcal?mol^?1 more stable than the least stable isomer X found on the potential energy surface. The transition states and minima isomers were verified by frequency calculation. Intrinsic reaction coordinate (IRC) calculations have been performed to confirm that each transition state is linked by the desired reactants and products. The isomer stabilities have been studied using the relative energies, chemical hardness and chemical potential. The MHP principle could not predict the order of stability for C₃H₃NO isomers as arrived at with the relative energies. The role of intramolecular hydrogen bonds on the equilibrium structure has been discussed. The energy barrier and reaction enthalpy have been calculated during isomerization.     

Direct excitation of the forbidden clock transition in neutral 174Yb atoms confined to an optical lattice

We report direct single-laser excitation of the strictly forbidden (6s2)1S0 <--> (6s6p)3P0 clock transition in 174Yb atoms confined to a 1D optical lattice. A small (approximately 1.2 mT) static magnetic field was used to induce a nonzero electric dipole transition probability between the clock states at 578.42 nm. Narrow resonance linewidths of 20 Hz (FWHM) with high contrast were observed, demonstrating a resonance quality factor of 2.6 x 10(13). The previously unknown ac Stark shift-canceling (magic) wavelength was determined to be 759.35 +/- 0.02 nm. This method for using the metrologically superior even isotope can be easily implemented in current Yb and Sr lattice clocks and can create new clock possibilities in other alkaline-earth-like atoms such as Mg and Ca.