Ionization of positronium (Ps) in collision with atoms

Ps ionization in Ps-atom scattering is of fundamental importance. The singly differential cross sections (SDCS) provides more accurate information to test a theory than integrated or total ionization cross section since the averaging over one parameter is not required. We evaluate the SDCS for Ps-ionization with respect to the longitudinal energy distribution of the break-up positron and electron in Ps-H and Ps-He scattering and compare them with the recently available experimental and theoretical data.     

Measurement of stimulated Brillouin scattering （SBS） threshold based on waveform variation of SBS optical limiting

This paper proposes a method for measuring the stimulated Brillouin scattering (SBS) threshold based on waveform variation of SBS optical limiting. The output waveforms for different pump power densities are numerically simulated, and validated in the Nd:YAG seed-injected laser system. The results indicate that SBS does not take place in the case of a low pump power density and thus the output power scales up linearly with pump power. Once the pump power density exceeds the SBS threshold, SBS takes place and thereby the energies are transferred from pump to Stokes. As a result, a small shoulder appears in the trailing edge of the output waveform, which provides another method to determine the SBS threshold.     

Synthesis,characterization, crystal structure and DFT studies on 3-(1H-benzo[d][1,2,3]triazol-1-yl)-1-(4-ethylphenyl)-1-oxopropan-2-yl-4-ethylbenzoate

3-(1H-benzo[d][1,2,3]triazol-1-yl)-1-(4-ethylphenyl)-1-oxopropan-2-yl-4-ethyl-benzoate (BEOE) has been synthesized and characterized by elemental analysis, IR, UV–vis and fluorescence spectroscopy. Its crystal structure has also been determined by X-ray single crystal diffraction. For the title compound, density functional theory (DFT) calculations of the structure and vibrational frequencies have been performed at B3LYP/6-31G* level of theory. Based on the vibration analysis, thermodynamic properties of the title compound have been calculated. The correlative equations between the thermodynamic properties and temperatures have also been listed. By using TD-DFT method, electron spectra of the title compound have been predicted, which suggests the B3LYP/6-31G* method can approximately simulate the electron spectra for the system presented here.     

杂质颗粒对受激布里渊散射介质光学击穿阈值影响的研究

建立了受激布里渊散射介质中热作用破坏的物理模型, 数值模拟了杂质颗粒的温度随其半径的变化曲线.结果显示,杂质颗粒存在一个最大热作用半径, 介质所含颗粒的尺寸在此半径附近时,介质最容易发生光学击穿现象, 其光学击穿阈值最低.在Continuum Nd: YAG种子注入式激光系统中,选取FC-3283, GF-180和HFE-7100介质, 通过不同孔径的过滤膜进行过滤,并研究了过滤前后的光学击穿阈值和能量反射率. 结果表明,随着过滤孔径的变小,介质光学击穿阈值逐渐提高, 且过滤之后介质的能量反射率有了明显的提高.介绍了一种利用He-Ne激光透射光光斑变化来判断是否发生光学击穿现象的方法,该方法具有方便、 准确的特点,可有效地减小由于肉眼观测引起的误差.     

Mbius不变的Q_p空间:结果、技巧和问题(英文)

本文是关于Mbius不变的Q_p函数空间方面的综述文章,给出了近10年来有关Q_p函数空间的若干结果、技巧和问题.     

Characterizations of α-Bloch spaces on the unit ball

We obtain a characterization of the α-Bloch space for any α>0 in the unit ball of Cn in terms of |f(z)−f(w)|/|z−w|. Moreover, a new characterization for the Bloch space is given.     

选用混合介质优化介质和控制受激布里渊散射特性的研究

本文提出了选用混合介质优化介质和控制其SBS特性的方案.分析了全氟碳化合物系列液体介质具有良好互溶性的缘故,数值模拟了HT-230/FC-72混合介质的增益系数、声子寿命和布里渊频移随混合比的变化曲线.在Countinuum Nd:YAG种子注入激光系统中测定了HT-230/FC-72混合介质的吸收系数和光学击穿阈值随混合比的变化,并实验研究了混合介质的能量反射率和Stokes光脉冲波形随混合比的变化.通过选用混合介质不仅优化介质,而且在一定范围之内可控制其SBS特性. 关键词： 受激布里渊散射 混合介质 优化介质 控制SBS特性     

查尔酮及其螺杂环衍生物的合成、晶体结构、抗氧化活性研究

为了合成新结构类型查尔酮衍生物,发现具有抗氧化活性的查尔酮类化合物,设计合成了查尔酮A和螺杂环B两种类型,共21个查尔酮类似物,结构经ESI-MS,ESI-HRMS和1H NMR确认.培养出螺杂环B1的单晶,通过X衍射确证了其为单斜晶系.其中螺杂环B为新结构类型化合物,通过1,3-偶极环加成反应,用不需加催化剂的"一锅煮"方法合成,该反应具有很好的立体选择性和区域选择性、且环境友好.用DPPH法测试了所有化合物的抗氧化活性,筛选出了多个对1,1-二苯基-2-三硝基苯肼(DPPH)自由基具有良好清除率的化合物,a环3,4-OH取代的两类化合物都具有良好的抗氧化活性,苯环邻位二羟基取代的查尔酮类化合物可能具有很好的抗氧化活性.