Fine and hyperfine structures of pionic helium atoms

The fine and hyperfine structures of pionic helium metastable states is calculated within the formalism of the Breit-Pauli Hamiltonian by using the variationally generated wave functions in Hylleraas coordinates.Our results not only verify the existing values of Hori et al.[Phys.Rev.A 89,042515(2014)]for the fine structure of π^(4)He^(+),but also determine the hyperfine structure of π^(3)He^(+).

Collisional Line Assignments and Hyperfine Structure Interpretation in Cs22^3△1g State

Accurately known energy level structure of the A＇∑u＋b3 IIu complex of states from a recent global de-perturbation of these states has enabled additional assignments of 140 perturbation facilitated infrared-infrared double resonance （PFIIDR） transitions to the 2^3△1g state from collisionally populated intermediate 1 ＋ A Eu levels. Together with the 221 previously observed 2^3△1g←A1∑u＋←X1∑g＋ Eu X Eg double resonance lines [J. Chem. Phys. 128, 204313 （2008）], molecular constants and the Rydberg-Klein-Rees potential energy curve of the 23△1g state have been recalculated （excluding 54 perturbed levels）. The centrifugal distortion constant has been determined and agrees well with the value calculated based on standard empirical formulas. The hyperfine structure of the 23△1g state, which has not resolved in our sub-Doppler excitation spectra of the 23△1g state, has been interpreted with a preliminary simulation.

Calculation of the hyperfine structure constants in ^(85)Rb and ^(133)Cs

For heavy atoms or ions, such as, Rb and Cs et al., relativistic effect must be considered in the calculation. In this paper, the relativistic many-body perturbation theory is used to solve the Dirac equation. And the zeroth-order hyperfine constants are evaluated with Dirac-Fock wave function. The finite basis sets of dirac equation are constructed by B-splines. With the finite basis sets the core polarization and the correlation diagrams are calculated. The hyperfine structure constants of the 5S1/2 and 6S<sub>1/2 states of 85Rb as well as the 6S1/2 and 7S<sub>1/2 states of 133Cs are evaluated.

Stark effect of the hyperfine structure of ICl in its rovibronic ground state:Towards further molecular cooling

Hyperfine structures of IC1 in its vibronic ground state due to the nuclear spin and electric quadruple interactions are determined by diagonalizing the effective Hamiltonian matrix. Furthermore, the Stark sub-levels are precisely determined as well. The results are helpful for electro-static manipulation （trapping or further cooling） of cold IC1 molecules. For example, an electric field of 1000 V/cm can trap IC1 molecules less than 637μK in the lowest hyperfine level.

Hyperfine Structure of La1 in a Cathode Discharge Tube

Hyperfine structures of La1 are reported using Doppler-free intermodulated fluorescence,Doppler-limited laser induced fluorescence and optogalvanic spectroscopy in a home-made cathode discharge tube.The constants A and B for the levels at 20197.34,21447.86cm^(-1) and constant A for the levels at 19379.40,18156.97,94910.38,and 24409.68cm^(-1) are reported.A homogeneous linewidth less than 40MHz and the different resolutions between fluorescence and optogalvanic spectroscopy were observed.

Investigation of the Hyperfine Structure of Atomic Niobium (Nb I) Spectral Lines Based on the Lower Energy Levels at 22936, 23010, and 23048 cm^-1

The hyperfine (hf) structure constants of three atomic niobium energy levels in the energy range around 23000 cm-1 (at 22936.90, 23010.58, and 23048.58 cm-1) are known with only limited accuracy, and the constants of combining levels are sometimes even unknown. Thus we performed laser spectroscopic investigations in the wavelength range between 5600 and 6500 &Aring;, and we excited altogether 16 transitions in which these lower levels are involved. Beside a more precise determination of the hf structure constants of the three lower levels (which were determined on several lines sharing a common upper level), these experiments led to the knowledge of the hf constants of nine levels with previously unknown constants. Beside these results, also the hf constants of 13 further energy levels are reported. For six of these levels, the constants were previously unknown.

Hyperfine structures and the field effects of IBr molecule in its rovibronic ground state

Hyperfine structures and the field effects of IBr molecule in its rovibronic ground state are theoretically studied by diagonalizing the effective Hamiltonian matrix.Perturbations of high-J levels up to 4 are taken into account when studying the hyperfine sub-levels of the J=0 level,and thus,an 80×80 matrix is constructed and solved.Some of the experimentally absent molecular constants are computed using Dalton program.Our results will be helpful in the experimental investigation of manipulation and further cooling of cold IBr molecules.

Mixed-field effect at the hyperfine level of^(127)I^(79)Br in its rovibronic ground state:Toward field manipulation of cold molecules

The mixed-field effect at the hyperfine level of the rovibronic ground state of the^(127)I^(79)Br(X^(1)Σ,v=0,J=0)molecule is computed on the J-I uncoupled basis of|JM_(J)I_(1)M_(1)I_(2)M_(2)>,where J is the molecular total angular momentum excluding nuclear spin,M_J is the projection number of J,I_(1) and I_(2) are the nuclear spins of the iodine and bromine atoms,and M_(1) and M_(2) are the projection numbers of I_(1) and I_(2),respectively.When the two applied electric and magnetic fields are parallel,the perturbations are rare and only one perturbation is observed in a relatively large field regime in our computation range.However,when the two fields are off-parallel,the perturbations increase significantly and some sublevels show the Feshbach-like resonance phenomenon.Therefore,such sublevels transit between weak-field seeking and strong-field seeking repeatedly,which can be utilized to enhance or suppress cold molecular collision and chemical reaction rates.Such behavior of the molecular hyperfine structure in the mixed off-parallel fields may also be utilized to construct an electric-field-assisted anti-Helmholtz magnetic trap for cold molecules and to realize evaporative cooling of cold molecules(sub-mK)into the ultracold regime(μK).

Hyperfine Constants for Low-Lying States in ^137Ba^＋

Relativistic many-body perturbation calculation is applied to calculate the hyperfine constants for the lowlying states 6S1/2, 6P1/2, 6P3/2, 5D3/2, and 5D5/2 in the alkaline earth ion ^137Ba^＋. The zeroth-order hyperfine constants are calculated with Dirac-Fock wave functions, and the finite basis sets of the Dirac-Fock equation are constructed by B splines. With the finite basis sets, the core polarization and the correlation effect are calculated. The final results for magnetic dipole hyperfine a constants are obtained.

Fine Structure Analysis of the Configuration System of V II. Part II: Odd-Parity Levels

The 3d34p, 3d35p and 3d24s4p odd configurations of the V II spectrum have been reanalysed and three 3d24s4p triplets are assigned higher energies than previously proposed. We have determined the fine structure parameters, the largest and next largest eigenvector percentages of levels, their calculated Landé gJ-factors and predicted positions for missing experimental levels up to 100,000 cm-1 for the 3d24s4p configuration. Furthermore for the first time a hyperfine structure (HFS) parametric treatment, involving levels of these two configurations has been carried out. The deduced single-electron HFS parameter values are successfully checked with those obtained by means of ab initio calculations.

Fine Structure Analysis of the Configuration System of V II. Part I: Even-Parity Levels

Using a linked-parameter technique of level-fitting calculations in a multi configuration basis, a parametric analysis of fine structure (fs) for even-parity levels of V II, involving six configurations, has been performed. This led us to exchange the assignments of two triplets, 3d3(2F)4s c 3F and 3d4 d 3F, reported in earlier analyses as being located at 30,300 cm-1 and 30,600 cm-1, respectively. This is confirmed by experimental hyperfine structure (hfs) A constants, used as fingerprints. Moreover, the current singlet 3d24s2 1D2 position is likely too high. The fs parameters, magnetic Landé g-factors, and the percentage of leading eigenvectors of levels are calculated. We present also predicted singlet, triplet and quintet positions for missing experimental levels up to 100,000 cm-1. The single-electron hfs parameters are determined in their entirety for 51V II for the model space (3d + 4s)4 with good accuracy. For the model space (3d + 4s)4 of 51V II the single-electron hfs parameters are computed;furthermore, our achieved theoretical evaluations of the single-electron hfs parameters, thanks to the use of ab initio calculations, reinforce the validity of these hfs parameter values, deduced from experimental data.

高电荷态类硼离子^(2)P_(3/2)—^(2)P_(1/2)跃迁的实验和理论研究进展

高电荷态离子(highly charged ion,HCI)的精细结构及辐射跃迁性质的精确测量不仅可以检验基本物理模型,包括:强场量子电动力学(quantum electrodynamics,QED)效应、电子关联效应、相对论效应、原子核效应等,而且能够为天体物理和聚变等离子体物理提供关键原子物理参数.相对于研究较多的类氢和类锂离子体系,类硼离子的精细结构禁戒跃迁的相对论效应和QED效应的贡献很大,高精度实验测量与理论计算为进一步检验多电子体系的基本物理模型提供了重要途径.此外,类硼离子也被认为是最佳的高电荷态离子光钟候选体系.本文主要介绍了类硼离子基态^(2)P_(3/2)—^(2)P_(1/2)跃迁的实验和理论研究最新进展,概述了其精细结构和超精细结构的研究现状,并讨论了使用电子束离子阱结合高分辨光谱学实验技术开展类硼离子超精细分裂实验测量的方案,为未来开展类硼离子超精细分裂实验研究并在更高精度上检验QED效应,提取原子核磁化分布半径,检验相关的核结构模型等研究提供了参考.

氢分子离子超精细结构理论综述

通过氢分子离子振转光谱的高精度实验测量和理论计算,可以精确确定基本物理常数,如质子-电子质量比、氘核-电子质量比、里德伯常数、以及质子和氘核的电荷半径.氢分子离子光谱包含丰富的超精细结构,为了从光谱中提取物理信息,我们不仅需要研究振转光谱跃迁理论,还需要研究超精细结构理论.本文回顾了氢分子离子精密光谱的实验和理论研究历程,着重介绍了氢分子离子超精细结构的研究历史和现状.在20世纪的下半叶就有了关于氢分子离子超精细劈裂的领头项Breit-Pauli哈密顿量的理论.随着21世纪初非相对论量子电动力学(NRQED)的发展,氢分子离子超精细结构的高阶修正理论也得到了系统的发展,并于最近应用到H_(2)^(+)和HD^(+)体系中,其中包括mα^(7) ln(α)阶量子电动力学(QED)修正.对于H_(2)^(+),超精细结构理论计算经过数十年的发展,可以与20世纪的相应实验测量符合.对于HD^(+),最近发现超精细劈裂实验测量和理论计算存在一定的偏差,且无法用mα^(7)阶非对数项的理论误差来解释.理解这种偏差一方面需要更多的实验来相互检验,另一方面对理论也需要进行独立验证并发展mα^(7)阶非对数项理论以进一步减小理论误差.

Hyperfine Structure of Several Soils from Western Hubei and Inner Mongolia Studied by Mossbauer Spectroscopy

Soil samples taken from Xilamuren Grassland,Resonant Sand Bay,Inner Mongolia,and Yichang,western Hubei Province were investigated by Mssbauer spectroscopy at room temperature and 20 K.This was supplemented with phase identification and elemental analysis to obtain information about the composition and structure types of Fe-containing compounds.The samples collected from both Xilamuren Grassland and Resonant Sand Bay,Inner Mongolia were found to have small amount of iron 1%-2%.The main phases were determined as silica,albite,and microcline.Two or three dominant doublets were observed in the Mssbauer spectra of these samples,respectively and identified as corresponding to the valence states of Fe2＋and Fe3＋.A sextet observed in all the spectra is attributed to the hematite phase.Low temperature Mssbauer measurements have revealed Morin transition.

Determination of hyperfine structure constants of 5D_(5/2) and 7S_(1/2) states of rubidium in cascade atomic system

We present a method to precisely determine the hyperfine structure constants of the rubidium 5D（5/2） and 7S（1/2） states in a cascade atomic system. The probe laser is coupled to the 5S（1/2）→ 5P（3/2） hyperfine transition, while the coupling laser is scanned over the 5P（3/2）→ 5D（5/2）（7S（1/2）） transition. The high-resolution double-resonance optical pumping spectra are obtained with two counter-propagating laser beams acting on rubidium vapor. The hyperfine splitting structures are accurately measured by an optical frequency ruler based on the acousto-optic modulator, thus, the magnetic dipole hyperfine coupling constant A and quadrupole coupling constant B are determined. It is of great significance for the atomic hyperfine structure and fundamental physics research.

The hyperfine structure of electron spin resonance spectrum of tricobalt cluster radical anion CH_3CCo_3(CO)_9^-

CH_3CCo_3(CO)_9 was synthesized from the reaction between chloralose and Co_2(CO)_. The radical anion was generated by electrochemical reduction,and electron spin resonance spectra in THF were recorded by in situ electrolysis in the sample tube in the ESR cavity at 298 and 110K with the spectral data

BrF分子电磁偶极跃迁转动超精细微波谱模拟

本文推导了BrF振动基态(X^(1)Σ,v=0)下J=1←0的转动超精细光谱的跃迁偶极矩,总结了跃迁选择定则为:△J=±1;△F_(1)=0,±1和△F=0,±1;而且,当△F_(1)=△F时谱线强度很强,反之很弱.当能级之间存在微扰相互作用时,某些谱线由电偶极和核磁偶极跃迁共同产生,然而磁偶极仅仅贡献大约十亿分之一的光谱强度.计算所得光谱线宽和相对强度与实验结果一致.同时,在|JI_(1)F_(1)I_(2)F>基矢下对Hamilton量矩阵对角化确定了转动超精细光谱的位置,与实验误差小于1/50谱线宽度(<10-8).最后模拟了微波转动超精细光谱,所得结果有助于超精细分子光谱实验和其他相关应用研究.

Control and data acquisition system for collinear laser spectroscopy experiments

A control and data acquisition system was implemented for the recently developed collinear laser spectroscopy setup.This system is dedicated to data recording,storage,processing,monitoring of the beam intensity and energy,and visualization of various spectra.In comparison to the conventional resonance nuclear reaction system,the key technique is the precise synchronization of the detected counts with the actual scanning voltage(or probing laser frequency).The functions of the system were tested by measuring the hyperfine structure spectra of stable calcium(e.g.,^(40)Ca^(+))and radioactive potassium(e.g.,^(38)K)in the bunched and continuous modes,respectively.This system will be routinely applied and further improved in subsequent laser spectroscopy experiments on unstable isotopes at the Beijing Radioactive Ion-beam Facility(BRIF).

类铝离子钟跃迁能级的超精细结构常数和朗德g因子

本文利用多组态Dirac-Hartree-Fock方法计算了类铝等电子序列从Si^(+)到Kr^(23+)离子基组态3s^(2)3p^(2)P_(1/2,3/2)能级的超精细结构常数和朗德g因子.通过系统评估电子关联效应对Si^(+)和Co^(14+)离子中所关心原子参数的影响,尤其是与内壳层电子相关的关联效应,构建了可靠精确的计算模型,除Si^(+)离子外,超精细结构常数和g因子的计算误差分别控制在1%左右和10^(-5)的量级.此外,进一步分析了超精细结构常数中电子部分矩阵元和g因子随原子序数Z的变化规律,并拟合了这些物理量与Z的定量依赖关系,利用拟合公式可以快速计算类铝离子在14≤Z≤54区间内任意同位素的超精细结构常数和g因子.

用于不稳定核性质研究的激光共振电离技术

不稳定原子核的基本性质反映了核的内在结构和有效相互作用,可用于研究不稳定核的奇特结构。激光核谱技术通过测量核外电子光谱的超精细结构和同位素移位,可以核模型无关地提取原子核的多个基本性质,是研究不稳定核性质和结构的有力工具之一。多步激光共振电离方法是测量原子或离子超精细结构和同位素移位的方法之一。基于此,国际上发展了多种共振电离谱实验技术,用于放射性核束装置上开展不稳定核基本性质和结构研究。本文首先介绍了激光共振电离方法,以及由此发展的各种共振电离激光谱实验技术。随后详细讨论了近十年来刚发展起来的共线共振电离谱技术。此技术可同时实现超精细结构谱的高分辨和高灵敏度测量,正在核素版图大质量范围内的不稳定核性质和结构研究中发挥重要作用。最后分析了用于国内放射性核束装置的共振电离激光谱技术的发展现状及应用前景。