钪原子的自电离里德伯能级3d4s(1D2)nf2 D3/2,3d4s(1D2)nf2 F5/2和3d4s(1D2)np2 D3/2<

在多通道量子亏损理论框架下,利用相对论多通道理论,分别在冻结实近似和考虑偶极极化下计算钪原子的J^π=(3/2)^-,(5/2)^-的三个收敛于 3d4s(¹D₂)的自电离里德伯系列的能级.对3d4s(¹D₂)np²D_3/2和3d4s(^{1 关键词： 相对论多通道理论 多通道量子亏损理论 电子-电子关联 自电离里德伯系列}     

用多步激发技术测定锶的(5p3/2ns)1及(5p3/2nd)3自电离谱

用分步激发方法及偏振光技术,测定了锶的(5p_3/2ns)₁(n=13-21)及(5p_3/2 nd)₃(n=13-24)各自电离谱,在低于5p_1/2电离限的(5p_3/2ns)₁态的实电子激发谱中,出现对应于(5p_1/2ns)₁及(5p_1/2nd)₁的畸变峰,畸变峰也出现于(5p_3/2nd)₃的实电子激发谱中。这说明(5p_jns)(5p_jnd)自电离系列间存在相互作用。 关键词：     

Nb XIII离子3d94s2, 3d94s4p, 3d94p2 组态能级结构与跃迁的理论研究

用准相对论Hartree-Fock方法对Nb XIII离子二电子激发组态3d⁹4s², 3d⁹4s4p, 3d⁹4p² 的能级结构做了全面系统的理论计算研究.在对已有研究结果分析的基础上, 运用最小二乘方法对径向积分参数进行了优化计算, 得到了与这些组态有关的电偶极允许跃迁的谱线波长和跃迁概率.计算结果与最新的实验值做了对比分析, 表明本文计算结果是准确的. 研究发现, 波长40.92 nm的谱线, 属于3d⁹4s(¹D)4p²F_7/2–3d⁹ (²D)4s^{2 2}D_5/2 的跃迁谱线, 而不属于3d⁹4s (¹D)4p⁴D_7/2–3d⁹(²D)4s^{2 2}D_5/2 的跃迁谱线, 即上谱项能级为²F_7/2, 而不是⁴D_7/2. 关键词： Nb XIII离子 二电子激发组态 谱线波长 跃迁概率     

Ba原子6pnd(J=1,3)自电离光谱的实验研究

采用三台可调渚激光实施孤立实激发,分三步将处于基态的Ba原子激发到6P1/2nd(J=1,3)和6p3/2nd(J=1,3)自电离态上,获得了分别从6snd1D2(n=7-15)和6sad3D2(n=7-12)激发而得到的6p1/2nd(J=1,3)和6p3/2nd(J=1,3)自电离光谱,重点对主量子数n较低的自电离态进行了实验研究.通过光谱的线形拟合得到了上述能级的位置和宽度等数据,进而获得了量子弓损和约化宽度等信息.通过对不同系列的自电离光谱的分析和比较,详细讨论了这些自电离态的光谱特征及其复杂光谱结构的成因.     

Cu吸附(SiO3)n(n=1—8)团簇几何结构和电子性质的密度泛函研究

运用密度泛函理论下的广义梯度近似和交换关联函数对Cu吸附(SiO₂)n(n=1—8)团簇的几何结构、电荷分布、稳定性和电子性质进行了较详细的研究,结果表明: Cu原子易于和带有悬挂键的Si原子作用并形成"铜岛膜"; Cu吸附(SiO₂)_n团簇后Si原子失去电子能力减弱,O原子得到电子能力增强;Cu(SiO₂)n(n 关键词： 密度泛函理论 2)_n (n=1—8)团簇')" href="#">Cu(SiO₂)_n (n=1—8)团簇 近红外吸收     

钐原子的两步激发共振光电离光谱

采用两步激发共振光电离技术研究了Sm原子的偶宇称高激发态光谱.实验采用了两条激发路线：1)第一束激光的波长固定在478.44nm以便将Sm原子从4f⁶6s²［⁷F₁］态激发至4f⁶6s6p［⁷D₁］态,再用第二束激光使其波长从480nm扫描至530nm,将Sm原子进一步激发至待测的高激发态;2)第一束激光的波长固定在574.8 关键词： Sm原子 光谱 分步激发 共振电离     

虚阴极产生微波的一些基本特性

用Vlasov-Poisson方程对相对论电子束在单板、双板间的传播过程进行了数值模拟,给出了单板模型空间电荷积累最大的位置,不同位置上的电流J、电子数密度n、电场E的振荡频率随入射电子数密度n₀、入射速度v₀的变化关系,双板模型空间电荷积累最大的位置,J、n、E的振荡频率随入射流J₀及两板间距离的变化关系。虚阴极位置的数值结果与稳态理论给出的结果相近,它的振荡频率符合经验公式(1~√2π)ω_peb。单板时入射电子数密度按速度服从高斯分布,能散△E_n/E_n < 10%时的数值结果给出与单能情况基本相同的结论。     

径向积分的解析计算

本文阐明的方法能方便地求出径向积分ⁿ₁^l₁F_Lⁿ₂^l₂(q)≡∫₀^∞> (R_n1^l₁(αr)jL(Kr)R_n2^l₂(αr)r²dr(q≡(K)/(α))的解析表达式。文中给出了L=0,1,2情况下各个径向积分的解析式,同时还以多重求和的形式络出了对各种量子数L,n₁,l₁,n₂,l₂适用的径向积分表达式。     

用双光子电离探测技术研究奇宇称的Sm原子光谱

采用两台激光器对Sm原子奇宇称激发态的光谱及其特性进行了系统研究.利用一台波长在585 nm到663 nm之间调谐的染料激光器,将Sm原子从某个4f⁶6s²⁷F_J(J=0—6)态激发到具有奇宇称的4f⁶6s6p或4f⁵5d6s²激发态.然后,采用波长固定在532 nm的强激光束,对处于上述奇宇称激发态的Sm原子进行双光子电离,以实现探测其光谱信息 关键词： 双光子电离 奇宇称态 Sm原子     

环二硅氨烷的29Si和13C NMR研究

本文报道了十种环二硅氨烷衍生物(R₁=Me、ф;R₂=Me、ф1 R₃=Me;X=Me、ф、OH、OSiMe₃、H和cl)及与此有关的九种聚合物m+n(m=2,3,4,7,10)的²⁹Si和¹³C化学位移,讨论了取代基X、R₁、R₂及硅氧链节数m对化学位移的影响。通过考察化学位移随R₁、R₂的变化,推断环二硅氨烷中N与其周围的三个Si之间存在(p→d)π相互作用。     

Energy levels of perturbed 6p<Emphasis Type="Italic">n</Emphasis>d <Emphasis Type="Italic">J</Emphasis>=2 Rydberg states of Pb I by multichannel quantum defect theory

Energy levels of the odd-parity 6pnd J=2 Rydberg states of atomic lead are analyzed by the multichannel quantum defect theory (MQDT) with previous experimental energy levels. The obtained. Using these parameters, admixture coefficients for each level are calculated to designate the level denotations. The results show that strong channel mixings exist for the levels near the 6pnd (3/2)[5/2]₂ ⁰ and 6p6d (3/2)[3/2]₂ ⁰ pertubers. The five-channel model different from that in literature is used to predict 21 energy positions of 6pnd (1/2)[3/2]₂ ⁰ levels and to determine the denotations of all the 6pnd J=2 Rydberg states under 59788 cm⁻¹ for Pb I.     

Two-color three-photon resonant excitation spectrum of strontium in the autoionization region

We report new studies of the odd parity autoionizing Rydberg series of strontium attached to the 4d( ² D _{3/2, 5/2}) ionic limits possessing J = 1-3 based on the two-color three photon resonant excitation technique in conjunction with an atomic beam apparatus. Using the 4d ²³ P ₀ intermediate levels, we have been able to record the autoionizing Rydberg series of J = 1 whereas, from the 4d ²³ P ₂ intermediate level the series of Rydberg levels possessing J = 1, 2 and 3 have been observed. The level assignments and the line shapes simulations of the autoionizing resonances have been made using the multichannel quantum defect theory. Received 21 November 2001 / Received in final form 2 May 2002 Published online 19 July 2002     

High resolution laser spectroscopy of Ba Rydberg atoms

The purpose of the present paper is to illustrate some selected aspects of high resolution laser spectroscopy of Rydberg atoms, rather than giving an extensive review of the state of the art. The following topics will be discussed: (i) Excitation and detection of Ba Rydberg atoms with principal quantum numbers up ton≲300; (ii) Stark effect and atomic diamagnetism of high-n Ba Rydberg states in thel-mixing region, (iii) Resonance in singlet-triplet mixing of 6snp¹P₁ and 6snd¹D₂ Ba Rydberg states deduced from hyperfine structure measurements.     

Stark effect,hyperfine structure and isotope shifts in highly excited states of BaI and CaI

The electric dipole polarizabilities of 9 even-parity barium states (6s8s ¹ S ₀,³ S ₁; 6s7d ¹ D ₂,³ D _1,2; 5d7s ¹ D ₂ and 6p ^{2 3} P _0,1,2) in the interval 33,800–35,800 cm^?1 have been measured with high resolution laser-atomic-beam spectroscopy. Simultaneously, values of isotope shifts and hyperfine coupling constants for theJ=1 states have been obtained. Comparison of the experimental polarizabilities with calculated values as well as inspection of the data on isotope shifts and hyperfine structure from the present and earlier work strongly suggests erroneous assignments of theJ=2 states, with an exception for the 5d 7s ¹ D ₂ state. The influence of an electric field on the 3d ^{2 3} P _0,1,2 states of calcium has also been studied. A marked departure from a quadratic Stark effect has been observed at relatively small field strengths. This can be attributed to the large polarizabilities of neighbouring Rydberg states. The low field data allow the determination of admixtures of Rydberg states into the 3d ^{2 3} P-states as small as 0.02%.     

Study of Ba 6p1/2ns (J=0,1) autoionizing series

With different polarization configurations the spectroscopic properties of Ba 6p_1/2ns (J=0) and 6p_1/2ns (J=1) autoionizing states have been studied systematically by using an isolated core excitation scheme. Level energies and widths of n members for the J=1 series with n=9–33 and for the J=0 series with n=9–10,12–20 are reported, most of which are observed for the first time. Further information about these two autoionizing series, such as energies of the higher n members and their interseries interactions with 6p_3/2nl series, are obtained by means of saturation excitation method. The experimental data on the J=1 series are analyzed with a 13-channel multichannel quantum defect theory, and general agreement between them has been obtained. Several parts of the experimental results are compared with those of previous works, and agree well with them.     

Experimental study of autoionizing states of AuI

This paper describes the investigation of the autoionizing states of AuI by exciting the states of 6d ² D _3/2 and 6d D _5/2 with tunable dye lasers by means of a resonance ionization time-of-flight mass spectrometer (RI-TOFMS). Many new autoionizing states were found, a few of which have narrow-linewidths of about 0.1 cm^–1. The photoionization efficiencies for different channels were compared. Among the autoionizing states found so far, the highest photoionization yield is given by two newly obtained states from the state 6d ² D _5/2, 3683.6 cm^–1 and 4636.5 cm^–1 above the first ionization limit. In addition, the Shore-Fano profile parameters of several autoionizing resonances were determined by a nonlinear fitting program.     

Molecular dissociative sequential excitation and ionization of strontium vapor

We report new measurements on laser-assisted molecular dissociative sequential excitation and ionization spectra of strontium vapor. A single Nd:YAG pumped dye laser in conjunction with an atomic beam apparatus have been used to investigate the even parity 5snd ^3,1 D ₂ Rydberg series resulting from the 5s5p ¹ P ₁ resonance level. The relative intensities changes among the 5snd ³ D ₂ and ¹ D ₂ Rydberg series are attributed to the interactions with the 4d6s ^1,3 D ₂ perturbers, respectively. The interchannel interactions between the 5snd ¹ D ₂ series and the 4d6s ¹ D ₂ level and among the 5snd ³ D _1,2,3 series and the 4d6s ³ D _1,2,3 intruders have been separately parameterized using the two-channel quantum defect theory. Received: 10 September 1998 / Received in final form: 16 December 1998     

Wn(n=3—27)原子团簇结构的第一性原理计算

使用密度泛函理论下的第一性原理方法,对W_n原子团簇(n=3—27)的结构特性进行了理论计算. 得到了W_n团簇(n=3—7)的最低能量结构和(n=8—27)的局域能量极小的典型结构. 使用凝胶模型,提出的电子组态1s²1p⁶1d¹⁰2s²1f¹⁴2p⁶3s ^{关键词： W团簇 结构性质 稳定性 从头计算}