Characterization of relativistic electrons generated by a cone guiding laser pulse

We demonstrated the interaction of a gold cone target with a femto second(fs) laser pulse above the relativistic intensity of 1.37×10 18 μm 2 W/cm 2.Relativistic electrons with energy above 2 MeV were observed.A 25%-40% increase of the electron temperature is achieved compared to the case when a plane gold target is used.The electron temperature increase results from the guiding of the laser beam at the tip and the intense quasistatic magnetic field in the cone geometry.The behavior of the relativistic electrons is verified in our 2D-PIC simulations.     

基于p偏振光双面反射的薄膜传感器光学参数的优化

ｐ偏振光在镀膜平板玻璃上、下表面反射光强比γ的角度调制曲线的性状与膜层光学参数密切相关。分析了γ与膜层折射率、消光系数及膜厚的相对梯度随光参数变化的着急为基于ｐ偏振光双面反射的薄膜传感器选择最佳参数提供了理论依据,计算表明该类型传感器对膜层折射率的测量分辨率高达１０＾－７。对不同工艺条件下得到的溶胶－凝胶ＳｎＯ２膜进行光学参数测定及初步气敏实验,结果表明ｐ偏振光双面反射可作为高灵敏度光化学传感器的     

Numerical calculation of energies of some excited states in a helium atom

The energies of some excited states with the total angular momentum L=0, 1 and 2. the total spin of two electrons S=0 and 1, and the even and odd parities are precisely calculated directly from the Schrödinger equation where the mass of the helium nucleus is finite. Moreover, we find that the solutions to the equation for the excited states have some more nodes, which can be used to distinguish the states with the same spectral term.     

改进的双曲等效法用于双站合成孔径雷达前视成像

双站合成孔径雷达(SAR)前视成像有着很多的潜在应用,比如在能见度很低的天气实现飞机的导航和盲降,提高飞机飞行的安全度等.然而实现双站SAR前视成像的难点在于其距离历程的双根式性,直接采用驻定相位原理对其分解将得到复杂的解析式,从而后续算法的推导变得困难.现有的双曲等效法可以将双根式距离历程等效为单根式,但由于该方法为距离历程的二阶近似,当用于双站SAR前视成像时,由于其较大的前视角,未完全等效的距离历程高次项造成的误差已经超出可以接受的范围.针对以上问题,本文首先提出了一种改进的双曲等效法,该方法通过引入新的补偿变量来提高距离历程的等效精度;然后在此基础上推导回波信号的二维频谱解析式,并给出了一种适用于双站SAR前视成像的距离多普勒算法;最后通过仿真实验,将原双曲等效法与改进方法的等效误差以及成像结果做对比,验证了本文算法的有效性和优越性.     

Anion recognition by alpha-arylazo-N-confused calix[4]pyrroles

The first example of substitution reaction in the free alpha-position of N-confused calix[4]pyrroles is reported: azo-coupling with various arenediazonium salts. The obtained azocompounds were used for studies of their anion-binding properties by UV-Vis spectroscopy.     

Dual-Atom Catalysts Derived from a Preorganized Covalent Organic Framework for Enhanced Electrochemical Oxygen Reduction

Dual-atom catalysts (DAC) are deemed as promising electrocatalysts due to the abundant active sites and adjustable electronic structure, but the fabrication of well-defined DAC is still full of challenges. Herein, bonded Fe dual-atom catalysts (Fe₂DAC) with Fe₂N₆C₈O₂ configuration were developed through one-step carbonization of a preorganized covalent organic framework with bimetallic Fe chelation sites (Fe₂COF). The transition from Fe₂COF to Fe₂DAC involved the dissociation of the nanoparticles and the capture of atoms by carbon defects. Benefitting from the optimized d-band center and enhanced adsorption of OOH* intermediates, Fe₂DAC exhibited outstanding oxygen reduction activity with a half-wave potential of 0.898 V vs. RHE. This work will guide more fabrication of dual-atom and even cluster catalysts from preorganized COF in the future.     

Solution-phase synthesis of spherical zinc sulfide nanostructures

A facile solution-phase method has been developed to synthesize specially hollow and solid ZnS nanospheres. High-resolution TEM images on the nanospheres suggest their formation via the oriented aggregation of the primary ZnS nanocrystals. The morphology and size of the ZnS nanospheres can also be tuned easily by controlling the experimental conditions. These special spherical structures are very easily encapsulated within a uniform silica layer without any surface modification, suggesting potential applications in biochemistry and biodiagnostics.     

Manipulating the Stacking of Triplet Chromophores in the Crystal Form for Ultralong Organic Phosphorescence

Provided here is evidence showing that the stacking between triplet chromophores plays a critical role in ultralong organic phosphorescence (UOP) generation within a crystal. By varying the structure of a functional unit, and different on‐off UOP behavior was observed for each structure. Remarkably, 24CPhCz, having the strongest intermolecular interaction between carbazole units exhibited the most impressive UOP with a long lifetime of 1.06 s and a phosphorescence quantum yield of 2.5 %. 34CPhCz showed dual‐emission UOP and thermally activated delayed fluorescence (TADF) with a moderately decreased phosphorescence lifetime of 770 ms, while 35CPhCz only displayed TADF owing to the absence of strong electronic coupling between triplet chromophores. This study provides an explanation for UOP generation in crystal and new guidelines for obtaining UOP materials.     

基于结构动力修改的桩基检测方法

采用结构动力修改技术研究桩身损伤检测，将其转化为在一定约束条件下拟合桩顶频响函数的优化问题。用遗传算法加以求解。文中给出的数值模拟试验和工程应用实例，显示该方法能在较大范围内可靠地反演出桩身横截面积、桩长、波速等参数，达到检测桩身缺陷的目的，实现测试和分析一体化，使桩基检测易于进行并且结果实用可靠。