α,α′-二氧代烯酮环二硫代缩酮的NMR研究

报道标题化合物的ＮＭＲ谱，利用１Ｈ，１３ＣＮＭＲ和ＤＥＰＴ等技术确定新化合物的化学结构，并归属了所有质子和碳的化学位移     

碳的一种新形态—C60

文论述了Ｃ６０的发现及其研究的最新进展，内容包括：历史上Ｃ６０研究中的几个重要的事件，Ｃ６０的合成及纯化方法，Ｃ６０的几何结构、振动光谱、电子光谱、电子能级，Ｃ６０的超导、磁化率等电磁性质，以及Ｃ６０的衍生物化学等；还讨论了Ｃ６０作为近几年化学中一项重要的发现给化学和物理工作者带来的机会和Ｃ６０在前沿研究中的重要意义．     

声化学新发展——纳米材料的超声制备

声空化所引发的特殊的物理，化学环境为制备具有特殊性能的新型材料提供了一条重要的途径，近年来，声化学处理已成为制备纳米材料的一种十分有效的技术，文章综合介绍了超声法制备纳米材料的主要类型，其中包括超声声解法，声化学还原法，超声共沉淀法，超声微乳液法等，并着重阐述了超声的作用原理和各种方法的特点。     

光引发和放电引发的脉冲氧碘化学激光器

光引发和放电引发的脉冲氧碘化学激光器氧碘化学激光器具有波长短、效率高、光束质量好、高储能、装置安全简便等优点。１９７８年美国空军武器实验室ＭｃＤｅｒｍｏｔｔ等人首次实现了连续波氧腆化学激光器出光［１］．由于氧碘化学激光器具有许多潜在的应用，这种新型高...     

声化学反应器研究进展

自八十年代后期以来，超声应用于有机合成、金属有机化学、电化学、聚合物化学等领域，取得了大量研究成果，引起了越来越多的化学工作者的兴趣[1-4]．利用超声波获取化学效应时，有许多实验参数需要加以控制，诸如超声频率、声强、处理时间、体系温度、外部压力、溶剂以及反应物浓度等．因此，为了适应声化学研究的需要，必须设计合适的反应器．国际上在这方面的研究十分活跃[5-11]，近年来研制和发展了许多新型的声化学反应器．本文拟对近年来国际上出现的实验室用声化学反应器作一简要介绍，以期对我国这方面的工作有所促进．一、液哨式…     

化学富集XRFA法测定岩石,土壤稀有和稀土元素

研究了化学富集ＸＲＦＡ法测定岩石、土壤中Ｎｂ，Ｔａ，Ｚｒ，Ｈｆ，Ｔｉ，ＲＥ等微量元素的方法。化学富集采用共沉淀子交换结合。富集后得到的稀有和稀土元素用薄样－Ｘ荧光光谱法测定，制订了一个用明胶做分散剂制薄样的方法。稀圾与稀土元素的检出限达０．０６－０．８μｇ／ｍｌ。精密度与准确度符合地球化学样品分析要求。     

物理技术在蔬菜病虫害防治中的应用

利用化学方法防治病虫害在病虫害防治中占据主要地位．但随着大量施用化学农药防治害虫，也带来了许多问题，一方面造成土壤、水体、蔬菜等的污染；另一方量，大量施用化学农药导致害虫的抗药性增强，使害虫防治难度越来越大．因此，为了克服化学方法防治病虫害的明显不足，使用非化学方法防治病虫害成为目前病虫害防治研究中的热点． 蔬菜病虫害防治的非化学方法主要有农业防治、生物防治、物理防治等．下面仅就物理防治方法作一些具体探讨． 一、应用光方法防治病虫害 １．灯光诱杀：许多夜间活动的害虫，如金龟子，具有趋光性，可以设置…     

多环芳烃^13C—NMR化学位移的理论模拟

本文利用ＣＮＤＯ方法对十个多环芳烃化合物的＾１３Ｃ－ＮＭＲ的化学位移进行了理论上的计算，并提出了一个联系分子电荷密度、键级和键长等参数的半经验公式，同时利用逆磁环电流，顺磁环电流，湾区推斥效庆和迫位效应的影响。又对多环芳烃的化学位移进行了校正，从而使得理论计算与实验值吻合得很好，通过对多环芳烃的＾１３Ｃ－ＮＭＲ化学位移的回是分析表明：回归系数达到０．９５，较好地反映了多环芳烃＾１３Ｃ－ＮＭＲ化学位     

化学富集XRFA法测定岩石、土壤中稀有和稀土元素

研究了化学富集ＸＲＦＡ法测定岩石、土壤中Ｎｂ，Ｔａ，Ｚｒ，Ｈｆ，Ｔｉ，ＲＥ等微量元素的方法。化学富集采用共沉淀与离子交换结合。富集后得到的稀有和稀土元素用薄样－Ｘ荧光光谱法测定。制订了一个用明胶做分散剂制薄样的方法。稀有与稀土元素的检出限达０．０６～０．８μｇ／ｍｌ。精密度与准确度符合地球化学样品分析要求。     

一些羰基钼化合物的^95Mo NMR研究

测定了１２个羰基钼化合物的＾９５Ｍｏ ＮＭＲ谱，比较了它们的化学位移，简单地讨论了Ｍｏ原子的氧化价态、相同金属之间、不同金属之间相互作用及配体取代基等因素对化学位移的影响。     

环状输出UR90束旋转非稳腔的实验研究

 提出一种适合于高功率超音速横流氧碘化学激光器的环状输出的UR90束转非稳腔,采用FFT 方法模拟了具有非均匀分布的小信号增益时最低阶模的光场强度分布。利用大口径铜蒸汽激光器, 通过实验研究了在放大倍率为1.21和1.13的情况下,环状输出UR90腔正向模与反向模的基本特性, 得到较好的实验结果。     

大长宽比矩形有源非稳腔模式的数值模拟

 利用快速傅里叶变换算法和薄层增益近似方法,在Matlab计算平台上,对大长宽比正支共焦有源谐振腔进行了数值模拟。得到了长宽比为3.6∶1的大功率化学激光器输出的近场模式强度和相位分布,以及理想聚焦下的远场光斑的强度分布。给出了由非均匀增益引起的强度分布不均对远场光斑的影响。得到的近场图像结果和实验结果基本一致,表明本方法可以对大长宽比矩形腔的输出模式进行仿真,从而为激光器的光束质量改善提供计算参考。     

Impact of the Characteristic Impedance of Coaxial Lines on the Sensitivity of a 750-MHz Electronically Tunable EPR Resonator

A 750-MHz electronically tunable resonator was investigated in terms of the sensitivity of electron paramagnetic resonance (EPR) signal detection. The conversion efficiency of the radio-frequency magnetic field was calculated for resonators with 50- and 100-Ω coaxial coupling lines using three-dimensional (3D) microwave field and microwave circuit simulators. Based on the simulation results, two tunable resonators were physically constructed and compared in terms of EPR signal sensitivity using a nitroxyl radical solution. While the resonator with 100-Ω coaxial lines provided 14% greater signal intensity, its signal-to-noise ratio was lower than that of the resonator with 50-Ω lines. To demonstrate the capability of the constructed tunable resonator for EPR imaging experiments, a solution of nitroxyl radical and the leg of a tumor-bearing mouse were visualized.     

千瓦级COIL-UR90实验研究

 首次报导了千瓦级化学氧碘激光器（COIL）采用束转动90°环形非稳腔(UR90)的实验结果,测量了输出光斑的近场相位分布及远场强度分布, 当激光输出平均功率为2kW时,光束质量因子b =3~4。     

Output beam analysis of high power COIL

As the output power of a chemical oxygen iodine laser (COIL) increases, the output laser beam instability appears as the far-field beam spot drift and deformation for the large Presnel number unstable resonator. In order to interpret this phenomenon, an output beam mode simulation code was developed with the fast Fourier transform method. The calculation results show that the presence of the nonuniform gain in COIL produces a skewed output intensity distribution, which causes the mirror tilt and bulge due to the thermal expansion. With the output power of COIL increases, the mirror surfaces, especially the back surface of the scraper mirror, absorb more and more heat, which causes the drift and deformation of far field beam spot seriously. The initial misalignment direction is an important factor for the far field beam spot drifting and deformation.     

非稳腔输出环状激光束的传输特性

本文从菲涅耳衍射积分公式出发研究了激光器非稳腔输出环状光束在空间的传输规律.由轴上光强的极值点位置给出了划分非稳腔传输空间的近场、中场和远场区域公式.理论计算结果表明,非稳腔输出端环状光束在中场区域激光能量逐渐向轴心方向转移,而在远场变为爱里型圆盘状光束的过程.在非稳腔脉冲TEA CO_2激光器上测得的实验结果与理论计算结果很好地符合.     

Finite-amplitude standing acoustic waves in a cubically nonlinear medium

The acoustic field in a resonator filled with a cubically nonlinear medium is investigated. The field is represented as a linear superposition of two strongly distorted counterpropagating waves. Unlike the case of a quadratically nonlinear medium, the counterpropagating waves in a cubically nonlinear medium are coupled through their mean (over a period) intensities. Free and forced standing waves are considered. Profiles of discontinuous oscillations containing compression and expansion shock fronts are constructed. Resonance curves, which represent the dependences of the mean field intensity on the difference between the boundary oscillation frequency and the frequency of one of the resonator modes, are calculated. The structure of the profiles of strongly distorted “forced” waves is analyzed. It is shown that discontinuities are formed only when the difference between the mean intensity and the detuning takes certain negative values. The discontinuities correspond to the jumps between different solutions to a nonlinear integro-differential equation, which, in the case of small dissipation, degenerates into a third-degree algebraic equation with an undetermined coefficient. The dependence of the intensity of discontinuous standing waves on the frequency of oscillations of the resonator boundary is determined. A nonlinear saturation is revealed: at a very large amplitude of the resonator wall oscillations, the field intensity in the resonator ceases depending on the amplitude and cannot exceed a certain limiting value, which is determined by the nonlinear attenuation at the shock fronts. This intensity maximum is reached when the frequency smoothly increases above the linear resonance. A hysteresis arises, and a bistability takes place, as in the case of a concentrated system at a nonlinear resonance.     

Optical resonator for high-power transverse flow CO2 lasers

A new design of the U-type resonator is described. In this way, a laser beam with symmetrical intensity profile (regarding to a symmetry plane) can be extracted from an active medium that exhibits gain asymmetry along one of the transverse directions. The whole area of the active medium cross-section can be used, and consequently the laser efficiency will be increased. This resonator structure was applied for efficiency power extraction (as a low order TEM modes laser beam) from a DC excited transverse flow CO₂ laser with cylindrical geometry. Although the cross-section area of the discharge was entirely used (including the cathode fall region), a symmetrical intensity profile of the laser beam (regarding to the two orthogonal symmetry planes) was obtained in the near field as well as in the far field; the gain asymmetry along the flow direction was compensated by the gas circulation fluidodynamical circuit with two counterflowing discharge channels. A double-U optical resonator was introduced in order to provide a laser beam with axial symmetry.For the practical construction of these two types of optical resonators we have developed two new types of 90° deflection elements: the first one, which does not reverse the image (and which has the properties of the pentaprism), and the second one, which rotates the image with 90° angle. Both elements exhibit good focusability if they are equipped with two concave mirrors.     

Experimental demonstration of plasmonic racetrack resonators with a trench structure

We fabricated and investigated a plasmonic racetrack resonator with a trench structure. Trench channel plasmon polaritons excited by end-fire coupling at a wavelength of 633 nm are observed in the fabricated racetrack resonator. The racetrack resonator also worked as a plasmonic racetrack resonator. The experimental and simulation results of the electric field distributions are in good agreement.     

化学反应机理对液氧煤油发动机尾焰红外特性影响研究

提出了一种液氧煤油发动机尾焰红外辐射特性计算方法,首先采用计算流体力学软件对液氧煤油发动机内流场进行计算,然后以获得喷管喉部截面参数作为入口边界条件计算发动机尾焰流场,最后以发动机尾焰流场参数分布为基础,采用有限体积法对发动机尾焰红外光谱辐射特性和成像特性进行计算,并对比验证了模型和方法的准确性。在此基础上,研究了化学反应机理和复燃反应过程对尾焰红外辐射特性影响。结果表明,采用多步化学反应能够准确模拟液氧煤油发动机内流场,温度相比热力学计算大3.34%,压力相比试车测量大2.89%;考虑复燃反应使尾焰红外辐射强度增强显著,在采用单步化学反应和多步化学反应两种工况下2~5波段红外辐射强度分别增大50%~100%和150%~170%,但不会影响尾焰红外光谱辐射特性和红外总辐射强度随探测角变化趋势;采用单步化学反应和多步化学反应都能够获得清晰结构的红外成像图像,但是前者2~5尾焰红外辐射强度要比后者增大90%~190%,且两种工况下发动机尾焰红外光谱辐射特性差别很大,尾焰红外总辐射强度随探测角变化趋势也不同。