国际上化学三重表征研究的反思与展望

化学三重表征自提出以来就备受研究者关注,并指导着化学学科教学的理论与实践。然而对于三重表征的一些基本问题和概念并没有形成一致的看法,在澄清和界定三重表征内涵的基础上,对近年来国际化学三重表征研究的新成果进行了探讨,相关研究可以为三重表征的进一步研究带来思考和启示。     

利用手持技术探究铜锌双液原电池中电解质溶液对电流的影响

利用手持技术探究了铜锌双液原电池中电解质溶液的浓度和种类对电流的影响。得出正、负极电解质溶液的浓度与原电池的电流在一定范围内呈正相关，浓度越大，电流越大，负极电解质溶液种类的改变对原电池的电流影响有限。     

Pulse Compression Based on Laser-Induced Optical Breakdown in Suspension

Pulse compression based on laser-induced optical breakdown in suspension is investigated. The physical mechanism behind it is analyzed theoretically and validated in the Q-switched Nd：YAG laser system. A 12-ns pump pulse is suppressed to 5ns With good fidelity in the front edge and sharp steepness in the trailing edge. The HT-270, which has a small gain coefficient and absorption coefficient, is used as a solvent, and therefore the disturbance induced by stimulated Brillouin scattering and absorption are minimized and the transmittivity is enhanced.     

受激布里渊散射介质——全氟聚醚的温度特性研究

受激布里渊散射(SBS)介质——全氟聚醚(PFPE)不仅具有低吸收高负载的SBS特性,还具有低的流点或高的沸点,可适合于较宽温度范围之内工作.通过分析PFPE的化学结构,对PFPE具有良好的SBS特性及独特物理化学特性进行了解释.在连续Nd:YAG种子注入激光系统中选用HT230,DET和HS260三种PFPE进行了不同温度下SBS特性研究.结果表明,PFPE不仅具有良好的SBS特性,还可以在低温或高温条件下工作,这为不同温度下研究SBS相位共轭镜打下了良好的基础.     

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.     

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     

Investigation on the effect of beam divergence angle upon output waveform based on stimulated Brillouin scattering optical limiting

This paper investigates the effect of beam divergence angle on output waveform based on stimulated Brillouin scattering optical limiting. Output waveforms in the case of different pump divergence angles are numerically simulated, and validated in a Nd:YAG seed-injected laser system. The results indicate that a small pump divergence angle can lead to good interaction between pump and Stokes, and a platform can be easily realized in the transmitted waveform. In contrast, a peak followed by the platform appears when the divergence angle becomes large.