Self-broadening of the Na 3S-5S and 3S-4D two-photon transitions

Self-broadening of the Na 3s-5s and 3s-4d two-photon transitions has been measured. The results agree with a calculation based on van der Waals interaction between excited and ground state Na atoms.     

Magic Wavelengths for the 1S-2S and 1S-3S Transitions in Hydrogen Atoms

The dynamic dipole polarizabilities for 1S,2S and 3S states of the hydrogen atom are calculated using the finite B-spline basis set method,and the magic wavelengths for 1S-2S and 1S-3S transitions are identified.In comparison of the solutions from the Schrodinger and Dirac equations,the relativistic corrections on the magic wavelengths are of the order of 10~(-2) nm.The laser intensities for a 300-E_r-deep optical trap and the heating rates at 514 and 1371 nm are estimated.The reliable prediction of the magic wavelengths would be helpful for the experimental design on the optical trapping of the hydrogen atoms,and in turn,it would be helpful to improve the accuracy of the measurements of the hydrogen 1S-2S and 1S-3S transitions.     

计算电子与原子Mg碰撞3^1S→3^1P跃迁散射截面

应用动量空间的耦合通道光学势方法计算了中等入射能量范围的电子与原子Ｍｇ的非弹性散射３１Ｐ的微分散射截面，１０个分立的通道和描述连续态激发的光学势被包括在这个计算中。在１０ｅＶ、２０ｅＶ和４０ｅＶ的计算结果与实验测量符合的非常好并表明包括连续态改进了大角度的微分散射截面。     

高剥离类钠离子3s2S—3d2电四极矩E2光谱跃迁的理论计算

 利用全相对论性多组态Dirac-Fock平均能级方法系统地计算了高剥离类钠离子3s²S—3d²D(Z=14～103）电四极矩E2光谱跃迁的能级间隔，跃迁几率和振子强度，计算中考虑了核的有限体积效应，Breit修正和QED修正，所得结果和最近的实验数据及理论计算值进行了比较，计算结果表明：高原子序数的高荷电离子的电四极矩E2光谱跃迁的跃迁几率和中性原子的电偶极E1的相当，在ICF和MCF高温高密度激光等离子体中，电四极矩E2光谱跃迁过程不容被忽视。     

激光诱导镁原子S—S,S—D禁戒跃迁

报道在镁金属蒸气中利用两束激光三光子共振激发原子３ｓｎｐ１Ｐ中高里德堡态时，观察到随泵浦激光功率的增强，出现３ｓ４ｓ１Ｓ０－３ｓｎｓ１Ｓ０、３ｓｎｄ１Ｄ２（ｎ≈１８～３２）偶宇称态偶极禁戒跃迁增强，以及３ｓｎｓ１Ｓ０能级移动现象，并解释为光泵过程引起的原子激发态碰撞效应。利用禁戒跃迁首次测定了Ｍｇ３ｓｎｓ１Ｓ０（ｎ＝２２～３０）能级。     

S+X双频旋转关节设计与仿真

为解决S+X双频合建大型测控天线S、X不能同时发射上行功率的技术难题,对天馈线系统主要组成部件包括：天线反射面、S/X双频馈源、S/X双频段旋转关节等进行了分析,并针对结构实现与电气设计上的技术难点,给出了解决方案：电气设计上采用TM01模式作为X频段圆波导主要传输模式,采用TEM模式作为S频段同轴波导传输模式;在结构上使用两通路同轴嵌套的形式,完成了双频关节设计;通过电气性能仿真,得到了满意的结果,据此完成了双频旋转关节方案设计。通过计算、仿真与优化,结果表明所设计双频关节的电气性能均优于指标要求。采用该方案设计的某S+X双频合建大型测控天线实际使用表明：S、X能同时发射上行功率,同时构成天地测控回路。     

Na原子中3S—4D双光子共振增强紫外相干辐射的观测和研究

用Na原子3S—4D双光子共振增强的受激超Raman散射、四波混频和光泵受激发射过程,获得230—340nm范围内两组紫外相干辐射,分析了这一系列紫外相干辐射的产生机制和谐线特性。     

Effects of osmotic manipulation of intracellular hydration of HeLa S-3 cells on their proton NMR relaxation times

Pellets of HeLa from suspension cultured cells in isotonic medium (300 mosmolar) were introduced into a Bruker CXP100 NMR spectrophotometer at 80 mHz within 5 min of the start of centrifugation. T1 and T2 times were measured within a total elapsed time of 20-25 min at 80 mHz and 37 degrees C, and averaged 1430 msec and 120 msec, respectively. Extrapolation to zero extracellular space gave a corrected T1 of 1370 msec. For cells collected after 10 min in hypotonic medium (down to 30 mosmolar) increased proton density correlated well with increased cell water content, but relaxation times did not rise in proportion to that predicted for the entry of "bulk" water (T1 of 4700 msec), except when swelling approached lysis point. Cells partially dehydrated by 10 min in hypertonic medium of up to 1500 mosmolar have also been analyzed, but once again the shortening of T1 was not proportional to the loss of "free" (bulk phase) water. At the upper limit of hypertonic treatment, lacunae or vacuoles of a watery nature separated within the cytomatrix, preventing maximum dehydration. The relationship of cell water to T1 is complex over the whole range of tonicity that HeLa S-3 cells tolerate. The data indicate, however, that hypotonically induced water probably has an average T1 time considerably lower than bulk phase water. In contrast, raising the total extracellular volume with medium had precisely the predicted effect on T1 time, further strengthening the case that water taken up by cell acquires a shorter T1 time. Cells adapting to hypotonic conditions oscillated in size and water content over 2-3 hr before returning to near their initial volume. Under these circumstances, T1 oscillated in the same way but with a reduced amplitude, consistent with the above findings.     

High-resolution 133Cs 6S-6D, 6S-8S two-photon spectroscopy using an intracavity scheme

This Letter presents an intracavity scheme for diode laser based two-photon spectroscopy. To demonstrate generality, three (133)Cs hyperfine transition groups of different wavelengths are shown. For the 6S-6D transitions, we achieved a 10(2) times better signal-to-noise ratio than in previous work [J. Phys. Soc. Jpn. 74, 2487 (2005)] with 10(-3) times less laser power, revealing some previously vague and unobserved spectra. Possible mutual influences between the two-photon absorber and laser cavity were investigated for the first time to our knowledge, which leads to the application of a reliable hand-sized optical frequency reference. Our approach is applicable for most of the two-photon spectroscopy of alkali atoms.     

p Annihilation in a quark rearrangement model including S- and P-waves

A quark-antiquark rearrangement mechanism is applied to S- plus P-wave p annihilation. Including the effect of configurations enables the model to account for up to 70% of the observed annihilation cross section. This is achieved only by including the widths of the mesons.     

Chiral recognition in electron scattering by S- and R-2-butanol

Experiments are described involving the low-energy scattering of electrons from the two optical enantiomers S- and R-2-butanol. Using a synchrotron radiation photoionisation source on the ASTRID storage ring, scattering spectra are reported between a few meV and 140 meV at an electron energy resolution of 1.6 meV. These data show electron dichroism at 35 meV, for scattering into the backward hemisphere, with a cross-section of 202.1 ± 8.0 Ų (4σ) and 182.8 ± 9.0 Ų (4σ) for S- and R-, respectively, with the racemic mixture lying at the average value. No dichroic effect could be detected in the integral cross-section within the accuracy of the experiment. A brief qualitative discussion is given of a possible electron dissociative attachment mechanism for the creation of homochirality in space, including a new feature involving feedback through enhancement of electron polarisation through scattering from non-racemic mixtures of enantiomers.     

S-5N全固态重复频率脉冲发生器

 主要介绍S-5N的结构及测试实验结果。S-5N型全固态重复频率脉冲发生器是目前国际上同类源中峰值功率和平均功率均为最大的一台。随负载大小的变化，S-5N脉冲发生器的输出电压为400～600kV，输出电流2～3kA，输出脉冲半高宽40～50ns，单脉冲输出能量40～65J。 S-5N脉冲发生器在300Hz重复频率条件下可连续工作，500Hz重复频率条件下可连续工作3min，平均输出功率高达30kW。     

Effect of S- and Sn-doping to the optical properties of ZnO nanobelts

In this study, the optical properties of S- and Sn-doped ZnO nanobelts, grown by thermal evaporation, were investigated. The sulfur and tin contents in the nanobelts were about 12% and 8% (atomic), respectively. The average widths of the S- and Sn-doped ZnO nanobelts were 73 and 121 nm, respectively. Room temperature photoluminescence (PL) spectroscopy exhibits significantly different optical properties for the two types of nanobelts. The PL result of the S-doped ZnO nanobelts shows the broad visible emission with no detectable ultraviolet (UV) peak, while the PL result of the Sn-doped sample shows two emission bands, one related to UV emission with a strong peak at 376 nm that is blue-shifted by 4 nm in comparison to pure ZnO nanobelts, and another related to green emission with a weak peak. A weak peak in the UV region at 383 nm appeared after annealing the S-doped ZnO nanobelts at 600 °C. Additionally, the annealed S-doped nanobelts show a stronger peak in the visible emission region in comparison to that observed prior to annealing. The Sn-doped ZnO nanobelts are also affected by annealing, as the UV emission peak is blue-shifted to 372 nm after annealing.     

Superradiating 4P-4S-3P cascade of sodium vapour arising on the leading edge of the exciting laser pulse

Investigations of the superradiating cascade of sodium vapour 4P-4S-3P ₁ = 2.21 µm and ₂=1.14 µm) arising on the leading edge of the exciting laser pulse were carried out. The dependences of the actual delay time _D of the ₁ pulse on the population rise time of the laser-excited 4P state were measured and compared with those calculated following the existing theoretical model. The dependence of the actual delay time _D on the inverse density of excited atoms 1/N* is also presented. Analysis of this dependence revealed the influence of the Doppler dephasing and of the second, ₂, transition on the formation of the ₁ superradiance.     

Rotational spectra of S- and S-containing isotopologues of laser ablation generated tin monosulfide

Using a newly constructed source, tin monosulfide is produced by the reaction between carbonyl sulfide and the products resulting from the ablation of tin metal by the pulsed output of a frequency-doubled Nd:YAG laser (λ = 532 nm). Entrained in argon carrier gas, SnS is introduced into the cavity of a Balle-Flygare Fourier transform microwave spectrometer that has a frequency range encompassing the two lowest rotational transitions (J = 1 − 0 and 2 − 1) for this molecule. Except for ¹¹⁵Sn³⁴S, spectra are obtained in natural abundance for all ³⁴S-containing isotopologues with naturally occurring tin isotopes. Additionally, spectra were obtained for the rare isotopologues, ¹¹⁵Sn³²S and ¹²⁰Sn³³S. Resolution of the hyperfine structure in the latter species allows a more precise determination of its ³³S nuclear quadrupole coupling constant. Spectra for all species containing ³⁴S are analyzed in terms of mass-independent Dunham parameters and are combined with all available isotopologues to determine Born-Oppenheimer breakdown terms for both tin and sulfur.