Pressure broadening studies on the 33D1-2 3P0 helium line by saturated-absorption techniques

Broadening and shift measurements on the 3³D₁?2³P₀ component of the helium line at λ=587.5 nm are reported. The saturated-absorption method is used. Measurements are performed at room temperature and at liquid nitrogen temperature. Homogeneous broadening constants are deduced from an analysis taking into account the effect of weak velocity-changing collisions. Broadening and shift constants are interpreted in term of a Lennard-Jones interaction potential. The very small shifts observed show the predominance of the repulsive core effect in the interaction potential.     

Experimental generalized oscillator strengths of the 61S0→61P1-excitation of barium

Experimental generalized oscillator strengths f(K²) for excitations of the 6¹P₁ state of Ba, measured at 200 eV and 300 eV, are compared with theoretical data obtained by Kim and Bagus. Theoretical and experimental data agree at K² < 0.3 a.u., but differ significantly at greater K².     

Ba原子6s6p1P1←6s6s1S0跃迁的光腔衰荡光谱

建立了一套光腔衰荡原子束吸收光谱测量装置,并对Ba原子的6s6p¹P₁←6s6s¹S₀吸收谱线用光腔衰荡光谱方法进行了测量,得到了Ba原子在553.548nm不同温度下的吸收谱线线型.实验结果表明,该装置测量吸收灵敏度达到6×10^-7. 关键词： 光腔衰荡 吸收光谱 Ba原子     

Impact broadening and shifts for 6sns 1S0 and 6snd 1D2 series of barium

Impact broadening and shifts of Ba transitions to parity forbidden Rydberg states have been measured using two-photon laser spectroscopy techniques. Broadening and shift rates for the 6sns ¹S₀ (10 < n < 19) and 6snd ¹D₂ (8 < n < 26) levels due to thermal collisional interactions with Xe, Kr and Ar as perturber gases are plotted. Perturbations due to configuration interactions are discussed.     

Charmonium-the 1P1 state

Based on a model which gives agreement with the observed hyperfine and fine splitting of the charmonium states, we predict the mass of ¹p₁ to be 3372 MeV, substantially lower than any previous predicted values. We have also estimated branching ratios and decay rates for the production of this state via channels which become accessible because of its low mass.     

Saturated absorption spectroscopy in the ultra-violet with a continuous-wave,frequency-doubled,ring dye laser; even isotope shifts on the 6d3D1-6p3P0 transition of HgI

A novel, single-frequency, continuous-wave, ring, dye laser with intra-cavity frequency-doubling has been developed, and used to carry out saturated absorption spectroscopy on the 6s6d³D₁-6s6p³P₀ transition of Hg I at 296.7 nm. Even isotope shifts have been measured by this technique on this transition and are: Hg204-202, 350 ± 10 MHz; Hg202-200, 345 ± 10 MHz; Hg200-198, 310 ± 10 MHz. The shift on transitions from the hyperfine state 6s6d³D₁ ($\text{F =}\text{3}\text{2}$) between Hg199 and Hg201 has also been measured, and is 225 ± 10 MHz.     

The forgotten 1D2 level of charmonium

The standard “charmonium” picture predicts four C=+1 states (³P₀, ³P₁, ³P₂, 2 ¹S₀) between ψ and ψ′. If these are identified with the four experimentally observed levels, serious difficulties arise. We remark that a ,,forgotten” ¹D₂ level (J^PC=2^?) is likely to be around 3.5 GeV. It may be identified with χ(2.45) or χ(3.50), avoiding the above above difficulties. The 2 ¹S₀ level has then yet to be discovered.     

Mixing between the 23S1 and 13D1Ds

Mixing between the 23S1 and 13D1Ds is studied within the 3P0 model. If mixing between these two 1 states exists, Ds1* （2700） ± and DsJ*（2860）± could be interpreted as the two orthogonal mixed states with mixing angle θ≈-80 °in the case of a special β for each meson. However, in the case of a universal β for all mesons, D_s1^*（2700） ± could be interpreted as the mixed state of 23S1 and 13D1 with mixing angle 12° < θ < 21° but D_sJ^*（2860）± seems difficult to interpret as the orthogonal partner of D_s1^*（2700）±.     

Optical pumping of a Ne(3P2) atom beam with a multimode laser

Stable optical pumping of a neon metastable atom beam is achieved using a multimode dye laser. The factors that give rise to this stability are discussed. The resultant polarized beam is suitable for the study of electron spin and orbital orientation dependences in a variety of metastable atom collision processes.     

New ab initio Potential Energy Surfaces for Cl(2P3/2, 2P1/2)+H2 Reaction

采用多参考组态相互作用的计算方法和很大的基组构造了Cl+H₂反应体系的一组新的三维从头算势能面. 该势能面包含Cl+H₂体系的能量最低的三个绝热态,并在非绝热近似下转化为四个非绝热势能面. 另外,旋轨耦合矩阵元也基于Breit-Pauli Hamil-tonian计算得到. 对角化这四个非绝热势能和两个旋轨耦合矩阵元组成的全耦合Hamiltonian,得到了三个考虑旋轨耦合后的绝热势能面.基于这组新势能面的非绝热动力学计算结果与最新的实验符合得很好,很好地解释了     

Lifetimes of the Si I 3p4s 1P1 and 3p3d 1P1 states

A beam of metastable silicon atoms was produced by collisional dissociation of silicon molecules and selectively excited by a pulsed dye laser. The lifetimes of the excited Si I states were directly determined from the fluorescence decay curve: $\text{τ(3p4s}{}^1\text{P}{}_1\text{) = 4.1 (4) ns}$, $\text{τ(3p4s}{}^3\text{P}{}_2\text{) = 4.4 (4) ns}$, $\text{τ(3p3d}{}^1\text{P}{}_1\text{) = 8.1(5) ns}$.     

Determination of the lifetime of the mercury 63P1 state

A pulsed tunable dye laser was used for a high resolution experimental study of mercury fluorescence from the 6³P₁ state. The output of the dye laser was frequency doubled into the 253.7 nm region using a potassium penta-borate crystal. Exponential decays were observed for each of the five individual components of the hyperfine structure separately and the effects of the trapping of resonance radiation on the observed lifetime of the 6³P₁ state of mercury were investigated for each resolvable component. Within experimental error, the natural radiative lifetime of the 6³P₁ state was found to be independent of the hyperfine component irradiated and a value of 122±2 nsec was obtained, consistent with results found by other methods.     

Durees de vie des niveaux 1D2 ET 1S0 du magnesium

Radiative lifetimes of the excited n¹S₀ (n = 4, 5) and n¹D₂ (n = 3, 4) states in magnesium have been measured by time resolved fluorescence technique using two photon excitation.     

Magneto-optical study of the 5ƒ2 → 5ƒ16d1 transition in UO2

High field Faraday rotation and magnetic circular dichroism measurements in the energy range between 1.4 and 5.4eV are reported for UO₂. The measurements are compared with two modified atomic models for the 5?² → 5?¹6d¹ transition using LS- and jj-coupling, respectively. Excellent agreement between theory and experiment is found only for a jj-coupling treatment of the final state.The Faraday rotation for magnetic saturation is estimated to be 3 × 10⁶ deg cm^?1 at 4.5 eV.     

Pressure shifts of 1D2 Rydberg states of Mg I

Pressure shifts of the 3snd ¹D₂ Rydberg states to n = 23 have been measured for He, A and Xe and found to agree with previous results for ²P states of alkalis. Improved term values for the energy levels from n = 13 to 23 have been obtained.     

Relativistic calculations of 3s2 1S0-3s3p 1P1 and 3s2 1S0-3s3p 3P1,2 transition probabilities in the Mg isoelectronic sequence

Using the multi-configuration Dirac-Fock self-consistent field method and the relativistic configuration-interaction method,calculations of transition energies,oscillator strengths and rates are performed for the 3s 2 1 S 0-3s3p 1 P 1 spinallowed transition,3s 2 1 S 0-3s3p 3 P 1,2 intercombination and magnetic quadrupole transition in the Mg isoelectronic sequence(Mg I,Al II,Si III,P IV and S V).Electron correlations are treated adequately,including intravalence electron correlations.The influence of the Breit interaction on oscillator strengths and transition energies are investigated.Quantum electrodynamics corrections are added as corrections.The calculation results are found to be in good agreement with the experimental data and other theoretical calculations.     

Sub-kilohertz optical linewidths of the 7F0 ↔ 5D0 transition in Y2O3:Eu3+

Homogeneous optical linewidths as small as 760 Hz (fwhm) have been observed in Y₂O₃:Eu³⁺ using delayed heterodyne photon echoes. Hyperfine and lifetime contributions to dephasing are estimated to contribute ? 300 Hz to this width, and the remainder is attributed to quasi-resonant energy transfer.     

Hg~+离子5d~(10)6s ~2S_(1/2)→5d~96s~2 ~2D_(5/2)钟跃迁同位素位移和超精细结构的理论研究

本文首先在Dirac-Hartree-Fock近似下理论评估了Hg~+离子5d~(10)6s ~2S_(1/2)→5d~96s~2 ~2D_(5/2)钟跃迁的质量位移(mass shift, MS)和场位移(field shift, FS)在其同位素位移(isotope shift, IS)中的相对贡献,发现MS远小于FS而可以被忽略.在此基础上,通过系统地考虑该原子体系中主要的电子关联效应,计算了这条钟跃迁FS的精确值以及涉及到的上下两个能级的超精细结构常数,并得到了几种稳定汞同位素离子该跃迁的IS和超精细结构分裂.其中,计算的~(199)Hg~+和~(198)Hg~+离子之间的钟跃迁频率偏移与已有实验测量值相比误差为2%左右.最终,本文给出了汞离子7种常见同位素该谱线的绝对频率值,为实验上的谱线测量提供了有效的理论依据.     

1S0 and 3S13D1 nucleon-nucleon potentials in the quark compound bag model

For nucleons interacting via formation of the quark compound bag the resulting potential is written in a general form. Explicit examples of potentials are constructed in the ¹S₀, ³S₁ and ³S₁-³D₁ states fitted to the experimental data at T_L ? 1 GeV. As an outcome the QCB energy levels (dibaryons) and NN admixture in QCB are obtained in good agreement with theoretical predictions.