硼离子同位素位移的计算

应用Grasp92 程序包,计算了11,10B2+的 跃迁和 跃迁的同位素位移。 跃迁的同位素位移为29828MHz, 跃迁的同位素位移为29840MHz。这些理论结果与最新的实验结果是相符合的。     

相对论多组态相互作用方法计算Mg~+离子同位素位移

采用相对论多组态相互作用方法研究了Mg~+离子3s~2S_(1/2)—3s~2P_(1/2)和3s~2S_(1/2)—3s~2P_(3/2)两条跃迁谱线的特殊质量位移系数和场位移因子,并计算了中子数8≤N≤20的Mg~+离子的同位素位移.计算结果与其他理论的计算值符合得比较好,与最新的实验测量结果比较,相对误差在0.13%到0.28%范围,是目前最接近Mg~+离子同位素位移实验测量的理论计算结果.该计算结果可为Mg~+离子同位素位移实验和理论研究提供参考,能够用于Mg~+离子的短寿命同位素的光谱测量实验以及利用Mg~+离子开展幻中子数N=8和N=20附近的奇异原子核特性研究等.所用的计算方法和电子激发模式也可以推广到其他核外电子数为11的多电子体系,用于开展相应的原子光谱结构计算和同位素位移的理论研究.     

氮原子同位素计算

本文利用多组态Dirac-Hartree-Fock和相对论组态相互作用的方法计算了氮原子的同位素¹⁴N和¹⁵N的四对能级跃迁：3s⁴P→3p⁴P°,3s⁴P→3p⁴D°,3s²D→5p²D°,和3s²P→3p²P°相应的特殊质量位移系数和场因子. 由计算所得的正常质量位移,特殊质量位移系数和场因子获得了氮原子同位素的正常质量位移、特殊质量位移和场位移. 同时将计算结果和报道的实验和理论计算结果进行了比较.     

采用相对论多组态Dirac-Hartree-Fock方法对Mg原子同位素位移的理论研究

利用相对论多组态Dirac-Hartree-Fock方法研究了Mg原子基态到低激发态~1S_0-~1P_1和~1S_0-~3P_1两条跃迁谱线的同位素位移参数,包括正常质量位移系数,特殊质量位移系数和场位移因子,并计算了~(24)Mg,~(25)Mg和~(26)Mg三个稳定同位素的同位素位移.在计算中采用了一种受限制的双电子激发模式,并将同位素位移计算结果与已有的实验测量和理论计算结果进行了对比.结果表明,用本文的研究方法计算的Mg原子同位素位移与其他理论结果和实验测量值十分符合.本文的计算结果可以为~(20-40)Mg同位素位移测量实验提供必要的参考,所用的计算方法也可以应用到其他类Mg体系(核外电子数等于12的离子)等多电子离子的光谱结构计算和同位素位移的研究中.     

锂原子同位素位移的计算(英文)

本文应用Grasp92程序包计算了~(5,7)LiI的2~2P_(3/2)到2~2S_(1/2)和2~2P_(1/2)到2~2S_(1/2)跃迁的同位素位移.2~2P_(3/2)到2~2S_(1/2)跃迁的同位素位移为10307 MHz,2~2P_(1/2)到2~2S_(1/2)跃迁的同位素位移为10207 MHz.这些理论结果和实验是相符合的.     

同位素位移实验测量

利用光栅光谱仪测量了氢－氘灯谱线的同位素位移。利用具有高分辨、选择性激发等特点的共线快离子束－激光光谱学方法测量了^142-146,148,150Nd^ 同位素位移，结合King-plot和理论计算得到质量位移、场位移和特殊质量位移。     

测量铀同位素位移光谱的方法和装置

测量铀同位素的高分辨位移光谱,目前多采用原子束光谱法[1].该方法的分辨率和准确度高,但是设备复杂昂贵,操作复杂,特别是很难避免铀的高温腐蚀和放射性污染.近年来,美国 Los Alamos实验室的R.A.Keller等人[2]提出用光电流光谱法测量铀同位素位移光谱,并采用天然铀空心阴极灯测量了238U-235U的位移光谱.但是该方法由于同位素丰度相差悬殊,丰度高的同位素谱线强,丰度低的谱线弱,严重影响测量的灵敏度与准确度.特别是使用的单光路测量系统还不能测量零位移光谱. 本发明的目的,在于改进光电流光谱法单光路系统测量铀同位素仕移光谱受同位素…     

石盐中硼含量及其同位素的准确测定

基于Cs₂BO+₂的正热电离质谱法测定样品中硼同位素时,硼含量的准确测定直接制约着硼同位素测定的成败。目前,使用电感耦合等离子体原子发射光谱仪(ICP-OES)测定高盐样品的硼含量仍然存在很大问题,主要体现在两个方面： 高盐的基体干扰和仪器检出限制约,而仅仅依靠简单的稀释无法很好的解决这些困难。因此对样品进行硼元素的预富集以及基体离子的去除是十分必要的。在使用硼特效树脂进行硼元素的吸附时发现部分钠离子也会被同时吸附,故采用3 mol·L-1的氨水可以洗脱大部分吸附的钠离子而不造成硼的损失,达到了去除基体的目的。随后使用10 mL 75 ℃的0.1 mol·L-1盐酸将硼特效树脂吸附的硼洗脱实现了样品中硼的富集。ICP-OES测定硼含量时,选择波长为208.900 nm,样品的加标回收率在106.00%～108.40%之间,检出限为0.006 mg·L-1,定量下限为0.02 mg·L-1。通过不同盐度下的12次重复实验,其相对标准偏差小于5%,在1.94%～3.37%之间,因此该方法是可行的,并不存在偶然误差。联合此方法和Cs₂BO+₂离子的正热电离质谱法,成功测定了8个地质石盐样品的硼含量及硼同位素组成。     

用激光光电流光谱法测量同位素位移

建立了用激光光电流光谱测量同位素位移的方法并测量了波长在５７８．２ｎｍ处铜的同位素位移，波工在５７６．２ｎｍ处铕的同位素位移以及波长在５７４．８ｎｍ处铀的同位素位移。     

钐原子高激发态能级位置和同位素位移测量

本文首次用共振增强消多普勒双光子光谱技术对钐原子四个高激发态偶宇称能级进行了实验研究,得到了这些能级的位置和相应跃迁的同位素位移数据.     

不稳定锂同位素移位的高精度测量实验方案(英文)

对丰中子晕核11Li的核电荷均方根半径的实验确定 ,特别是其与9Li的半径的差值 ,将对各种核模型进行灵敏的检验 .选择锂的合适跃迁 ,利用激光光谱技术高精度测量该跃迁的同位素移位 ,并扣除精确理论计算的质量移位贡献值 ,可以用来确定有关同位素的核电荷均方根半径 .就目前能够提供的实验设备和手段 ,对于不稳定锂的同位素8,9Li和短寿命丰中子晕核11Li而言 ,这是能够得到与核模型相独立的电荷半径值的唯一可行的方法 .这类实验正在德国重离子研究中心 (GSI)和欧洲核子中心的ISOLDE/CERN上计划实施 .描述了锂原子的激光激发共振电离途径和进行锂的同位素移位测量的实验装置,并讨论了采用这种方法测量到的6,7Li的初步结果及其精度 ,以及使用该方法研究不稳定核的灵敏性. A high-resolution isotope shift measurement of lithium isotopes in a suitable transition, combined with an accurate theoretical evaluation of the mass-shift contribution in the corresponding transition, can be used to determine the root-mean-square nuclear charge radii of these isotopes. For the unstable 8,9Li and the short-lived halo nucleus 11Li, this is the only approach available for obtaining nuclear-model-independent values of the charge radii within the reach of present-day facilities...     

Isotope shift studies in the spectrum of boron monosulphide

The spectrum of boron monosulphide has been excited in microwave discharge and photographed at moderate dispersion. TheC ²Π _r ?X ²Σ⁺,B ²Σ⁺?A ²Π _i andA ²Π _i ?X ²Σ⁺ band systems extending from 2100–9000 Å have been obtained for B³²S and B³⁴S species. Isotope shifts for all these band systems have been measured. Comparison of the observed isotope shifts with the theoretically calculated isotope shifts confirms the emitter as well as the vibrational assignments of all these band systems.     

重离子冷却储存环CSRm双电子复合实验研究类锂36,40Ar15+离子同位素移动

配备电子冷却装置的重离子储存环为开展高电荷态离子的双电子复合（dielectronic recombination,DR）精密谱学研究提供了绝佳的实验平台。本工作在兰州重离子加速器冷却储存环主环（HIRFL-CSRm）上开展了类锂36,40Ar15+离子的双电子复合实验,实验观测了电子-离子质心系能量范围为0~35 eV的双电子复合速率系数谱。通过外推法获得了36,40Ar15+离子2s_1/2→2p_1/2和2s_1/2→2p_3/2的跃迁能量。同时利用GRASP2K程序理论计算了36,40Ar15+离子2s_1/2→2p_1/2和2s_1/2→2p_3/2跃迁的质量移动因子和场移动因子,进而得到双电子复合谱的同位素移动值。36,40Ar15+离子2s_1/2→2p_1/2和2s_1/2→2p_3/2同位素移动分别为0.861 meV和0.868 meV。它们均小于目前CSRm上双电子复合实验的实验分辨为~10 meV,进而解释了实验测量的DR谱上未能观察到同位素移动的原因。然而,高电荷态离子的同位素移动场效应与原子序数Z5成正比,因此,在重离子加速器冷却储存环实验环（HIRFL-CSRe）以及未来大型加速器--强流重离子加速器装置（HIAF）上有望通过DR精密谱学方法研究高电荷态重离子甚至放射性离子的同位素移动,进而获得相关原子核的核电荷半径等信息。The cooler storage ring is equipped with an electron-cooler. It is an excellent experimental platform for dielectronic recombination (DR) experiment of highly-charged ions. In this paper, the dielectronic recombination experiments of lithium-like Ar15+ ions with mass number 36 and 40 are conducted at the HIRFL-CSRm(main ring of the Cooling Storage Ring of Heavy Ion Research Facility in Lanzhou). The experimental electron-ion collision energy scale is from 0 eV to 35 eV. Extrapolation method is exploited to obtain the excitation energies of transitions 2s_1/2→2p_1/2 and 2s_1/2→2p_3/2 of the 36,40Ar15+ ions from experimental data. Meanwhile, GRASP2K program is utilized to calculate the mass shift factors and field shift factors of 36,40Ar15+ ions for 2s_1/2→2p_1/2 and 2s_1/2→2p_3/2 transitions to obtain isotope shifts in DR spectra. In theoretical calculation, isotope shifts of 36,40Ar15+ ions corresponding to 2s_1/2→2p_1/2 and 2s_1/2→2p_3/2 are 0.861 meV and 0.868 meV, respectively. They are both less than the experimental precision (~10 meV) of these dielectronic recombination experiments at the CSRm, which explains that isotope shifts cannot be distinguished from the experimental dielectronic recombination spectra. However, the field shift of highly-charged ions is proportional to Z5. In the future, the dielectronic recombination experiments of highly-charged heavy ions even radioactive ions will be conducted at the HIRFL-CSRe (experimental ring of the Cooling Storage Ring of Heavy Ion Research Facility in Lanzhou) and the future large accelerator facility--HIAF(High intensity Heavy-ion Accelerator Facility) to measure isotope shifts to obtain the nuclear charge radius information.     

Isotope shift calculations for D lines of stable and short-lived lithium nuclei

The isotope shifts(TSs) for the 2s~2S_(1/2) to 2p~2P_J(J = 1/2,3/2) transitions of the lithium nuclei including the stable and short-lived isotopes are calculated based on the multi-configuration Dirac-Hartree-Fock method and the relativistic configuration interaction approach.The results are in good agreement with the previous theoretical and experimental results within a deviation less than 0.05%.The methods used here could be applied to the IS calculations for other heavier Li-like ions and few-electron systems.     

Interpretation of the Vapor Pressure Isotope Effect of BF3

The available experimental data on the vapor pressure isotope effect (VPIE) of BF₃ are interpreted within the framework of the statistical theory of isotope effects in condensed systems. It is shown that the temperature dependence of the VPIE of ¹⁰BF₃/¹¹BF₃ observed by Rayleigh distillation experiments cannot be rationalized at all, while the curie obtained by vapor pressure difference measurements seems to be too steep below the boiling point.     

Definitive Carbon-13 Chemical Shift Assignments in 2-Substituted Adamantane Derivatives by Deuterium Isotope Effects

Deuterium isotope effects on carbon-13 chemical shifts in 5-[²H]-isotopomeres of ten 2-substituted adamantane derivatives were determined and used for complete assignment of their carbon-13 NMR spectra.

The carbon-13 NMR spectra of ten 2-substituted adamantane derivatives have been assignated by consideration of deuterium isotope effects. Some four- and five-bond downfield deuterium effects on certain chemical shifts have been measured and attributed to remote hyperconjugative interactions.     

Break-Through Investigation on Uranium Isotope Separation in the System Uranyl Ion Solution Ti(III)-Cationic Resin

A break-through experiment on separation of uranium isotopes was carried out by use of a cation-exchange resin in Ti(III) form. By analyzing the experimental results the apparent equilibrium constants of the order K = 1·00021–1·00034 were determined.

The maximum value on the experimental curies of the isotopic ratio versus effluent volume was interpreted by considering two antagonistic isotope effects: one relatively large given by an exchange reaction between U(IV) in resin and U(VI) in solution and another smaller given by the reduction reaction of U(VI) with Ti(III). The difference of the equilibrium constants of the these two isotope effects as a function of temperature was used for the determination of the apparent thermodynamic values of the resultant process, determined experimentally: ΔH⁰ = 0.8542 cal mol^?1 and ΔS⁰ = 3.33×10^?3cal°K^?1.     

Analysis of the Mass-spectrometric Double-beam Method for the Determination of Isotope Abundance Variations

The only method used for exact determinations of slight variations in natural isotope abundances is the mass-spectronietric double-beam method with standard comparison. With measurements on gases having isotope ratios up to 100:1 δ-value deviations of <0·1‰ can be achieved. As international comparisons have frequently shown this applies only to the random error in analyses performed with a certain type of mass spectrometer. Thus, a comparison of analyses made by IAEA, Vienna, in 1969 displayed a range of scattering of up to 2‰, i.e. twenty times the smallest possible instrumental error (see, e.g., [1]).