硼基态等电子序列磁偶极M1精细结构间隔和光谱跃迁参数

采用全相对论量子力学GRASP2程序,选取三电子组态1s22s22p, 1s22s2p2, 1s22p3,有限核费米模型,Breit和QED的高阶微扰修正,系统地研究了类硼等电子序列磁偶极M1 1s22s22p*"2P3/2-2P1/2( Z=10～100)光谱跃迁的精细能级结构间隔,跃迁概率和振子强度,计算结果表明1s22s2 2p和1s22p3组态之间存在明显的非动力学组态相关,采用三电子组态计算的精细能级结构间隔较单电子组态的计算结果有了显著的改善.     

紫外光区S_2分子激光诱导荧光光谱

利用真空脉冲放电超声射流气体束(H_2S/Ar~3%混合气体)的方法产生了气相S_2分子,并研究了30 400~34 400cm~(-1)范围内S_2分子的时间分辨和基态振动频率分辨的激光诱导荧光光谱,获得了184支谱带的高分辨率(0.1cm~(-1))和低分辨率(0.3cm~(-1))转动光谱。实验观测并归属了S_2分子B_u~(Σ-)-X~3Σ_g~-和B″~3Π_u-X~3Σ_g~-共84支振动跃迁,分析得到了激发态B~3Σ_u~-态ν=0~9和B″~3Π_u态ν=2~12的分子常数以及B~3Σ_u~-态的基态平衡分子构型。由于S_2分子B~3Σ_u~-与B″~3Π_u态之间存在微扰,这两个电子激发态的振动能级间隔、自旋分裂常数和自旋-轨道分裂常数变化不规律,转动跃迁强度和跃迁选择定则存在异常,利用~3Σ-~3Π的齐次微扰哈密顿量定性地对这些异常光谱进行了解释,进一步丰富了S_2分子紫外区低能电子激发态的信息。     

PuN基态和低激发态的分子结构与相对论有效原子实势

用Pu的三种不同相对论有效原子实势 (RECP)和密度泛函(B3LYP)方法对PuN基态和低激发态(4Σ+、6Σ+、8Σ+、10Σ+)的分子结构进行了计算,得到了相应的平衡几何构型和谐振频率.采用最小二乘法拟合得到了PuN分子的Murell-sorbie势能函数,在此基础上推导出完整的力常数和光谱数据,并与实验值作对比.结果表明:PuN的基态为X6Σ+,其余为低激发态;在三种RECP中,对于ωe的计算,60个中心电子的SDDRECP/B3LYP给出的结果与实验值符合得比较好(如X6Σ+:ωe=840.77 cm-1,ωeχe=5.73·"cm-1,De=5.880 6 eV,Re=0.176 3 nm,Be=0.408 4 cm-1,αe=3.3E-03 cm-1).计算还给出了相应的电荷布居、自旋密度、电偶极矩和能量特征等系列分子的性质.     

Theoretical study of potential energy curves,spectroscopic constants,and radiative lifetimes of low-lying states in SeO molecule

The low-lying potential energy curves of SeO molecule are computed by means of ab initio multireference configuration interaction technique, taking into account relativistic (scalar plus spin-orbit coupling) effects. The spectroscopic constants of Ω states for X³Σ^-, a¹Δ, b¹Σ⁺, A³Π, A'³Δ, and A"³Σ⁺ states are obtained, and they are in good accordance with available experimental values. The Franck-Condon factors and transition dipole moments to the ground state are computed, and the natural radiative lifetimes of low-lying Ω states are theoretically obtained. Comparisons of the natural lifetimes of Ω states with previous experimental results and those of isovalent TeO molecule are made.     

Experimental determination of the nu5 cis-bending vibrational frequency and Renner-Teller structure in ground state (X2Piu) C2H2+ using laser induced reactions

The spectrum of the nu(5) cis-bending vibration of ground state (X(2)Pi(u)) C(2)H(2)(+) has been recorded applying the method of laser induced reactions in a low-temperature 22-pole ion trap. It is obtained by counting the number of products of the reaction C(2)H(2)(+) (v(5) = 1) + H(2)--> C(2)H(3)(+) + H as a function of the laser wavelength. The vibronic transitions Delta-Pi and Sigma-Pi with their corresponding spin-orbit and Renner-Teller substructure have been observed. Using a perturbative analysis, the vibrational frequency has been determined to omega(5) = (710 +/- 4) cm(-1) and the Renner-Teller parameter epsilon(5) is on the order of 3 x 10(-2).     

Fourier Transform Spectra of the E(2)Pi(u)-X(2)Pi(g)((3/2)) System of CuCl(2)

High-resolution Fourier transform spectra of the laser-induced fluorescence of (63)Cu(37)Cl(2) produced in a cell have been recorded following excitation of a single vibronic level of the E(2)Pi(u) electronic state. Fluorescence occurs in combination bands to a broad spread of levels in the ground electronic state. A global vibronic model is proposed for the ground state based on an effective Hamiltonian, which fits the experimental data (2782 fluorescence lines, lower state quantum numbers: v(1) = 0-6, v(2) = 0-2, v(3) = 0-6, and J = 4(1/2)-80(1/2)) to 0.019 cm(-1) rms error. Vibrational, rotational and Renner-Teller parameters are obtained (e.g., omega(2) = 95.195(36) cm(-1), B(e) = 0.055106(3) cm(-1), epsilon = -0.1893(28)). A revised value for the equilibrium internuclear distance Cu-Cl is deduced: r(e)(Cu-Cl) = 0.20341(3) nm. The energy diagram of vibronic levels in the ground state is plotted up to 4000 cm(-1). Copyright 2000 Academic Press.     

Laser spectroscopy of jet－cooled CuF in visible region

The laser-induced fluorescence excitation spectra of jet-cooled CuF have been recorded in the range of 19000－21470cm^{-1}, in which the CuF radicals were produced by the reaction of SF_6 with copper atoms from a dc discharge-sputtering source under supersonic jet conditions. Eight observed vibronic transition bands have been assigned as the transition from the ground state X(^1Σ^+) to B(^1Σ^+), C(^1Π) and an unreported upper state. The rotational structure of all observed bands has been analysed at the estimated rotational temperature 80K. We determined the newly observed band to be the (^1Π, v=1)－X(^1Σ^+v=0) transition according to the character of the rotational structure and the isotopic shift analysis. In addition, the lifetimes of the states involved in these bands were measured.     

Potential energy functions for the ground state X3Σ- and excited state 1Σ+ of UO

Based on group theory and atomic and molecular reactive statics (AMRS), the ground state X³Σ^? and excited state ¹Σ⁺ of UO and their reasonable dissociation limits are derived successfully. Using the MP2 method with the relativistic e? ective core potential and valence electron basis set (5s4p3d4f)/[3s3p2d2f] for the U atom and basis set 6-311G* for the O atom, the present work has calculated the potential energy curves for the ground state Χ³Σ^? and excited state ¹Σ⁺ of UO. The equilibrium distance and dissociation energy are 0.1833 nm and 6.9241 eV for the Χ³Σ^? state, and 0.1825 nm and 8.8756eV for the ¹Σ⁺ state. Spectroscopic data are derived for the first time.     

Co24+离子1s23s-1s2np跃迁的波长和振子强度

用全实加关联方法计算了Cu26+离子1s23s和1s2np (n £ 9)态的非相对论能量;在计算相对论效应和质量极化效应对体系能量的一级修正、估算高阶相对论修正和QED修正的基础上,计算了该离子1s23s-1s2np的跃迁能、波长和在三种规范下的振子强度,得到与现有实验数据符合得很好的结果.与量子亏损理论结合,将对该离子能量和振子强度的理论预言准确地外推到包括连续态的整个能域.     

Cu26+离子1s23s-1s2np跃迁的波长和振子强度

用全实加关联方法计算了Cu26+离子1s23s和1s2np (n  9)态的非相对论能量.在计算相对论效应和质量极化效应对体系能量的一级修正的基础上,通过引入价电子的有效核电荷,在类氢近似下,估算了对能量的高阶相对论修正和QED修正,计算了该离子1s23s-1s2np的跃迁能, 波长和在三种规范下的振子强度.得到与现有实验数据符合得很好的结果.与量子亏损理论结合,将对该离子能量和振子强度的理论预言准确地外推到包括连续态的整个能域.     

Experimental investigation of ultracold atom-molecule collisions

Ultracold collisions between Cs atoms and Cs2 dimers in the electronic ground state are observed in an optically trapped gas of atoms and molecules. The Cs2 molecules are formed in the triplet ground state by cw photoassociation through the outer well of the 0-(g) (P3/2) excited electronic state. Inelastic atom-molecule collisions converting internal excitation into kinetic energy lead to a loss of Cs2 molecules from the dipole trap. Rate coefficients are determined for collisions involving Cs atoms in either the F=3 or F=4 hyperfine ground state, and Cs2 molecules in either highly vibrationally excited states (nu'=32-47) or in low vibrational states (nu'=4-6) of the a3 summation(u)+ triplet ground state. The rate coefficients beta approximately 10(-10) cm3/s are found to be largely independent of the vibrational and rotational excitation indicating unitary limited cross sections.     

LiCl~–阴离子的光谱性质和跃迁性质

采用多参考组态相互作用方法结合全电子基组计算了LiCl~-阴离子5个电子态(X~2Σ~+,A~2Π,B~2Σ~+,3~2Σ~+,2~2Π)的电子结构.为了得到精确的光谱常数,计算中考虑了Davidson修正、芯-价电子关联效应和自旋-轨道稱合效应.拟合得到各电子态的光谱常数、分子常数、自发辐射速率和自发辐射寿命.基态的光谱常数与实验值和其他理论值符合较好,同时报道了LiCl~-阴离子激发态的光谱常数以及其到基态的跃迁性质.计算结果表明A~2Π?X~2Σ~+跃迁具有高对角分布的弗兰克-康登因子f₀₀,第一激发态A~2Π有较短的自发辐射寿命.构造A~2Π(v’)? X~2Σ~+(v")准循环跃迁进行激光冷却LiCl~-阴离子需要一束主激光和两束抽运激光.以上结果预测了激光冷却LiCl~-阴离子是可行的.     

Electronic states and spectroscopic properties of MgH in absence and presence of spin–orbit coupling − a configuration interaction study

Electronic spectrum of astrophysically important molecule magnesium hydride (MgH) has been studied using configuration interaction methodology excluding and including spin–orbit coupling. Potential energy curves of several spin-independent (Λ?S) electronic states have been constructed and spectroscopic constants of low-lying bound Λ?S states within 8.2 eV of term energy are reported in the first stage of calculations. The X²Σ⁺ is identified as the ground state in the Λ?S level. In the subsequent stage, the spin–orbit interaction has been incorporated and its effects on the potential energy curves and spectroscopic features of different electronic states of the species have been investigated. The X²Σ⁺_1/2 is identified as the spin–orbit (Ω) ground state of the species. Transition moments of several dipole-allowed transitions are computed in both the stages and radiative lifetimes of the corresponding excited states are computed. Electric dipole moments (µ) for a number of low-lying bound Λ?S states as well as several low-lying Ω-states are also calculated in the present study.     

SiCl自由基X2Π和A2Σ+态的光谱性质

采用内收缩多参考组态相互作用(ic MRCI)方法结合Dunning等相关一致基,计算Si Cl自由基X²Π和A²Σ⁺态的势能曲线.讨论参考能和相关能外推对X²Π和A²Σ⁺态光谱的影响.对势能进行相对论修正及核价修正计算.拟合势能曲线得到X²Π和A²Σ⁺态的光谱常数.它们与实验结果一致.利用Breit-Pauli算符,计算旋轨耦合效应,得到X²Π_1/2和X²Π_3/2的势能曲线、并计算它们的光谱常数.求解双原子分子核运动的径向SchrÖdinger方程,获得无转动SiCl自由基2个Λ-S态及X²Π态的耦合分裂态的全部振动态.得到J=0时X²Π态的自旋-轨道耦合常数、较高振动态的惯性转动常数以及X²Π_1/2和X²Π_3/2的振动能级等分子常数.     

Adiabatic Energies of Excited Σu States of the Hydrogen Molecule

Accurate Born-Oppenheimer potential energy curves and adiabatic corrections are computed for the six lowest ¹Σ_u states of the hydrogen molecule. For the 4¹Σ_u-6¹Σ_u states adiabatic term values of the vibrational levels supported by the potentials and the corresponding rotational constants are given. For the outer potential well of the 6¹Σ_u state, Franck-Condon factors are listed for the possible transitions to the HH?¹Σ_g state.     

锂分子31Πg里德堡态的光谱研究

我们用脉冲光学-光学双共振荧光激发谱(OODR),测量了在35 500～38 000 cm-1能量范围内的里德堡态,观察到7Li231Πg态的10个振动能级.本文对观测的31Пg态的146条激发谱线进行了归属,得到了新的Dunham常数,RKR势能曲线以及A1Σ+u到31Πg态跃迁的夫兰克-康登因子,并且讨论了31Πg态的双重分裂以及与附近里德堡态F(4)1Σ+g,51Σ+g,61Σ+g和G(2)1Πg的微扰.发现在我们的实验精度下(0.2 cm-1) 31Πg态的双重分裂可以忽略.     

Thermally Averaged Spectroscopic Parameters of the Weakly Bound Dimers

Spectroscopic parameters in an ensemble of the weakly bound dimers are derived making use of the quantum and classical statistical average over thermally excited rovibrational states. Argon dimers and oxygen dimers are taken as examples. It is shown that thermally averaged characteristics of dimers rapidly change as temperature of a gas rises. In an ensemble of quasi-diatomic tightly bound dimers, the high-temperature limit of the effective dissociation energy amounts to roughly D(0)/3, where D(0) is the dissociation energy from the ground state. It is demonstrated that the effective rotational B(eff)(T) constant for the oxygen dimers statistically averaged at near room temperature is merely one half of the ground state B(0) value. This conclusion is in agreement with recent spectroscopic observations. Rotationally resolved spectroscopic probe of (O(2))(2) in the slit-nozzle expansion resulted in B(0) = 0.095 cm(-1), while bandshape analysis of the room-temperature collision-induced absorption in the oxygen fundamental allowed an estimate of B(eff) approximately 0.038 cm(-1). The role of anisotropy of intermolecular interaction and the formation of various types of metastable dimeric states are discussed. Copyright 2001 Academic Press.     

类锂体系(Z=21—30)基态1s22s电离能和相对论项能的理论计算

使用全实加关联方法和里兹(Ritz)变分方法计算了类锂体系(Z=21—30)基态1s²2s的非相对论能量和波函数；包括动能修正、电子-电子接触项、轨道-轨道相互作用项以及Darwin项的相对论修正和质量极化项由全实加关联波函数的一阶微扰给出，量子电动力学修正QED(quantum electronic dynamic)由有效核电荷方法和类氢公式计算；给出了中等核电荷的高电离类锂体系基态的电离能、相对论效应的项能(term energy)，并将计算结果与实验数据进行了比较，表明FCPC 关键词： 类锂体系 全实加关联 电离能 项能