估算等离子体效应对类氢离子束缚态能级能量影响的新公式

在均匀电子气模型下,通过求解Dirac方程,计算了类氢离子束缚态能级能量与等离子体密度的关系,得到了能近似估算能级能量随等离子体密度变化的新拟合公式,该公式同样可以用以估算不同束缚态能级发生压致电离时的临界电子密度.通过与自洽场离子球模型计算结果的比较,作为一种简单和快捷的计算方法,均匀电子汽模型在近似计算束缚态能级能量及压致电离临界电子密度方面是自洽场离子球模型得很好近似方法.     

The atomic structure and the properties of ununbium (<Emphasis Type="Italic">Z</Emphasis> = 112) and Mercury (<Emphasis Type="Italic">Z</Emphasis> = 80)

A super heavy element Uub (Z = 112) has been studied theoretically in conjunction with rela-tivistic effects and the effects of electron correlations. The atomic structure and the oscillator strengths of low-lying levels have been calculated, and the ground states have also been determined for the singly and doubly charged ions. The influence of relativity and correlation effects to the atomic properties of such a super heavy element has been investigated in detail. The results have been compared with the properties of an element Hg. Two energy levels at wave numbers 64470 and 94392 are suggested to be of good candidates for experimental observations.     

Investigation of the hyperfine structure of Ta I lines (VI)

We have classified about 200 new lines and have discovered 13 energy levels with even parity and 1 level with odd parity by means of the systematic hyperfine structure investigation of a large number of spectral lines of the neutral tantalum atom. For the new levels we deduced their angular momenta, parity and magnetic hyperfine interaction constants A as well as the electric quadrupole interaction constants B. Received 8 August 2001     

Investigation of the hyperfine structure of Ta I lines (V)

We report on further investigations of the hyperfine structure of spectral lines of the neutral tantalum atom. Besides determination of the hyperfine constants A and B of 21 levels we report on the discovery of 9 up to now unknown fine structure levels for which we could determine their energy position, parity, angular momentum and the constants A and B. For a large number of up to now unclassified lines the combinations could be identified. Received 27 June 2000 and Received in final form 23 August 2000     

铯原子7S1/2态磁偶极超精细常数的测量

在室温下的原子气室中, 基于铯原子6S_1/2-6P_3/2-7S_1/2(852.3 nm+1469.9 nm) 阶梯型能级系统, 利用电光调制器的主频和±1级边带分别产生的三套双共振吸收光谱, 当驱动电光调制器的信号源频率严格等于7S_1/2态超精细分裂的能级间隔时, 三套谱线中的一些超精细跃迁谱线重叠且线宽最窄, 利用这一现象很好地避免了激光器频率扫描时非线性效应的影响, 测量出了7S_1/2 态超精细分裂能级间隔: 2183.72 MHz±0.23 MHz, 并计算出该态的磁偶极超精细常数: A_hfs= 545.93 m MHz±0.06 MHz, 与文献中报道的测量结果一致.     

超重元素Bh（Z=107）的激发态结构和共振吸收率的理论预言

在成功预言了100号元素Fm低激发态能级结构的基础上，通过系统考虑电子相关效应和相对 论效应，使用MCDF方法进一步预言了107号元素Bh的几个较低的激发态能级以及由基态到这 些激发态的共振吸收率.期望预言的结果会对进一步的实验工作提供一定的帮助. 关键词： 超重元素 MCDF方法 低激发态结构     

A Detail Investigation on the Synthesis of Superheavy Element Z = 119

Physics of Particles and Nuclei Letters - We have studied the α-decay properties of superheavy nuclei Z = 119 in the range 265 ≤ A ≤ 316. By studying the α-decay properties,...     

Isomer separation and measurement of nuclear moments with the ISOLDE RILIS

Short-lived radioisotopes are element selectively ionized by the resonance ionization laser ion source (RILIS) of the on-line isotope separator ISOLDE (CERN). The relative production of low and high spin isomers can be significantly changed when a narrow-bandwidth laser is used to scan through the atomic hyperfine structure. This allows the assignment of gamma ray transitions to the decay of the individual isomers. Moreover, the measurement of the hyperfine splitting provides a very sensitive method for the determination of magnetic moments of exotic isotopes. The technical developments are discussed for the example of copper. This revised version was published online in August 2006 with corrections to the Cover Date.     

First observation of atomic levels for the element fermium (Z=100)

The atomic level structure of the element fermium was investigated for the first time using a sample of 2.7x10(10) atoms of the isotope 255Fm with a half-life of 20.1 h. The atoms were evaporated from a filament and stored in the argon buffer gas of an optical cell. Atomic levels were sought by the method of resonance ionization spectroscopy using an excimer-dye-laser combination. Two atomic levels were found at wave numbers (25 099.8+/-0.2) and (25 111.8+/-0.2) cm(-1). Partial transition rates to the 5f(12)7s(2) (3)H(e)(6) ground state have been determined from their saturation characteristics. Multiconfiguration Dirac-Fock calculations suggest that the leading orders of these levels could be the 5f(12)7s7p (5)I(o)(6) and 5f(12)7s7p (5)G(o)(5) terms.     

直接鉴别超重元素Z和A的一种新的可能方法

随着合成的超重元素向超重岛逼近,合成截面越来越小,同时,合成的超重元素的寿命可能相对增长, 这对利用α衰变链的传统方法鉴别超重元素是非常不利的。 讨论了可能突破这个瓶颈的一种可以直接鉴别超重元素原子序数Z和质量A的新方法, 即与RFQ离子阱技术相结合的激光多步共振电离方法, 对实现这种方法的途径、 该方法所面临的困难和挑战、需要进行的前期研究工作以及该方法的可能性和可行性进行了较详细的讨论。 With the synthesis of heavy elements approaching the super heavy island, the production cross section becomes smaller and the lifetime of the super heavy element becomes longer, which results in the difficulties for identification of theelements by using conventional alpha decay chain technique. In order to overcome the difficulties, a novel approach to direct identification of atomic number Z and nuclear mass A for super heavy elements is proposed, namely, the multi step resonant laser ionization of singly charged ions in combination with RFQ trap. The routine for the experiment is presented, and the possibilities, feasibilities, as well as the problems to be faced, are discussed in detail.     

^143Pm高自旋态研究

通过熔合蒸发反应^129Te(^19F,4nγ）布居了^143Pm的高自旋态,利用在束γ谱学方法,对^143Pm的高自旋态核结构进行了研究,测量了γ射线单谱和γ－γ符合谱,并进行了γ射线各向异性以及DCO比率分析,建立了激发高能达10535．4keV的能级纲图,其中包括新发现的32条γ射线和17个新能级,用弱耦合模型对^143Pm的晕态能级结构进行了解释。     

铥原子激发能级超精细结构常数的测定

用铥空心阴极灯,采用光电流光谱技术测得铥原子21条一级跃迁谱线,确定了相应跃迁上能级的超精细结构常数,其中7个能级的参数为首次发表,运用同一空心阴极灯,采用双色双光子级联共振技术,由荧光法首次测得4个第二激发能级的超精细结构常数.     

通过48Ca+249Bk 合成Z=117的可能性研究

利用两步模型对可能合成 Z=117 的核反应48Ca+249Bk 进行了研究。模型将熔合过程分为弹靶接触前的粘连过程和从弹靶接触到形成复合核的形成过程。结合统计蒸发模型,计算了297117 蒸发数个中子的剩余截面。结果表明,在激发能 E* = 31 MeV且复合核蒸发3中子时的剩余截面最大为 0.34 pb ,已经可以用实验方法进行探测。     

^139LaⅠ超精细结构光谱测量

本文用激光光电流光谱方法研究了~(139)LaI五个奇宇称能级的超精细结构,其中三个是首次报道.采用最小二乘拟合,得到了这些能级的磁偶极超精细结构常数A.     

Novel Experimental Method in the Study of Double Rydberg States by Laser Resonance Excitation

1.IntroductionSequentia1multisteplaserexcitationhasbeenextensivelyusedtostudydoublyexcit-edstatesofa1ka1ine-earthatoms.Mostoftheinvestig8tionsconcernedthedoublyexcitedstatesinwhichoneofthetwovalenceelectronsishighlyexcitedandtheotherisweaklyexcited[1].Inthecasewhenbothvalenceelectronarehighlyexcited(doubleRydbergstates),onlyafewresultswereobtainedduetothelimitutioninexPerimentaltech-nique['j.ThelimitationarosefromvariousaSpectS.First,duringthesequentiallaserex-citationofdoubleRydbergstatesw…     

An electron spectroscopic determination of theL I energy in the elements Sodium (Z=11) to Copper (Z=29)

Energies of atomic electrons in theK andL shells of eighteen elements of low atomic numbers have been measured by electron spectroscopy. Tabulated values for theL _I energies are shown to be in need of considerable revision. AluminumKα radiation is shown to have high potentialities for ESCA studies.     

Investigation of the Magnetic Hyperfine Field at 140Ce on Gd Sites in GdCo2 Compound

Perturbed angular correlation experiments on ¹⁴⁰La–¹⁴⁰Ce probes substituting for the Gd positions on GdCo2 demonstrate that the magnetic hyperfine field (MHF) on Ce atoms follows an expected Brillouin function but with a substantially reduced saturation value as compared with the MHF acting on free Ce⁺³ ions. The results were interpreted with the aid of first principles electronic structure calculations showing that the reduced value of the MHF is a consequence of a small orbital contribution to the MHF which was attributed to the de-localization of the Ce 4f electronic state.     

Aln(n=2～7)团簇的结构和能级分布

采用密度泛函B3LYP的方法研究了小原子团簇Al2～7的几何结构和能级分布,分析了随团簇原子数的增加,团簇的几何结构和费米能级的变化情况.研究结果表明:Al2～7的团簇的几何结构在5个原子以前为平面结构,而从六个原子开始为空间立体的稳定结构.电子壳层结构表明,在铝团簇中没有出现非常明显的象碱金属那样的稳定幻数结构.在Al2～Al7团簇中,能级结构呈现明显的分立特征,费米能级随着原子个数的增加而减小,到Al7时又有所增加,且团簇的能量间隙最小.     

NnHn(n=3～7)氮氢化合物的结构质理论研究

本文对53种NnHn(n=3～7)氮氢化合物进行了理论计算,应用自然键轨道理论(Nature Bond Orbital,NBO)和分子中的原子理论(Atoms In Molecules,AIM)分析了化合物的成键特征、相对稳定性.氮原子孤对电子与氮氮键以及氮氮键相互之间的超共轭作用是影响氮氮键长的重要因素.采用原子基团...     

NnHn(n=3~7)氮氢化合物的结构与性质理论研究

本文对53种NnHn(n=3~7)氮氢化合物进行了理论计算,应用自然键轨道理论(Nature Bond Orbital, NBO)和分子中的原子理论(Atoms In Molecules, AIM)分析了化合物的成键特征、相对稳定性。氮原子孤对电子与氮氮键以及氮氮键相互之间的超共轭作用是影响氮氮键长的重要因素。采用原子基团法,比较了化合物的原子基团能量和原子基团生成热。通过预测53种化合物的稳定性,找出了氮氢化合物的稳定性与结构之间的一些规律,为预测氮氢化合物的稳定性提供了新的方法和新的数据。