氟丙烯在高温下的热稳定性

用单脉冲激波管研究了全氟丙烯C3F6的分解。使用H2作为清扫剂。产物包括CH4、C2F4、CF3H和C2F3H,作为对断键反应过程的指示。C3F6的断键反应为 C3F6CF3+C2F3 （1） 得到其速率常数表达式为 k（C3F6CF3+C2F3)=10(17.4±0.2)exp-(355300±8360)/(RT)s-1 温度范围为1090K相似文献   

二溴卡宾与CH3OH多通道反应的理论计算

对单、三重态CBr2与CH3OH的多通道反应进行了理论计算. 在b3lyp/6-311g*水平上优化了势能面上构型并进行了构型确认. 计算了各物种经零点能校正的CCSD(T)能量. 结果表明, 单重态CBr2既可以与O－H键插入生成1,1-二溴代甲醚P1 (CH3OCHBr2), 也可以与C－H键插入生成2, 2-二溴代乙醇P3(Br2HCCH2OH). 同时, 存在单重态CBr2与CH3OH抽提双氢生成Pabs(CH2O+CH2Br2)的反应. 采用统计热力学及Wigner校正的Erying理论研究了主反应通道的热力学及动力学性质, 并对反应通道上的关键点进行了NBO和AIM分析.     

CH3CH2+O(3P)反应机理的理论研究

利用abinitio方法对CH3CH2+O(3P)反应进行了理论研究,在MP2/6311+G(d,p)水平上优化得到了反应途径上的反应物、中间体、过渡态和产物的几何构型和谐振频率,并在QCISD(T)/6311+G(d,p)水平上进行单点能计算.计算结果表明:CH2O+CH3、CH3CHO+H和CH2CH2+OH是主要反应产物,其中CH2O+CH3主要来自反应通道A1:(R)→IM1→TS3→(A),CH3CHO+H主要来自反应通道B1:(R)→IM1→TS4→(B),CH2CH2+OH主要来自直接抽提反应通道C1和C2:(R)→TS1(TS2)→(C).计算结果同时表明该反应生成CO的通道能垒是非常高的,CO应该不是主要产物.     

单脉冲激波管中1,2-二氯乙烷的热裂解

在单脉冲激波管上 ,研究了 1,2 二氯乙烷的热裂解 .实验的激波条件为 :温度区间 10 2 0K 相似文献   

CH(X2∏)+N2O的反应机理研究

在G2(B3LYP/MP2/CC)理论水平上研究了CH(X^2Ⅱ)自由基与氧化二氮（NNO）分子的反应。计算了反应体系的最低二重态势能面上各驻点的构型参数、振动频率和能量，揭示了此反应存在的两种机理和六个通道。基中HC和NNO复合，生成中间体HC(N)NO，解离得到产物HCN+NO，这是最主要的通道之一；HC插入NO键，克服38.9kJ/mol的势垒，产生富能的中间体HC(O)NN，预测了五个反应通道，其中主要反应通道为：NN+HCO.     

CH3与NO2的反应

用时间分辨傅立叶红外光谱法和量子化学计算，研究了CH3自由基与NO2的基元反应．由248 nm激光光解CH3Br或CH3I得到CH3自由基．首次观测到了振动激发的产物OH、HNO和CO2．另一产物NO也被证实．由此确定了反应通道CH3O+NO，CH2NO+OH 和HNO+H2CO．其中CH3O+NO是主要的反应通道．还用CCSD(T)/6-311++G(df,p)//MP2/6-311G(d,p)的方法对上述通道的机理在理论上做了研究．理论计算的结果与实验观察相符．     

CH(X~2∏)+N_2O的反应机理研究

在G2 (B3LYP/MP2 /CC)理论水平上研究了CH(X2 ∏ )自由基与氧化二氮 (NNO)分子的反应 .计算了反应体系的最低二重态势能面上各驻点的构型参数、振动频率和能量 ,揭示了此反应存在两种机理和六个通道 .其中HC和NNO复合 ,生成中间体HC(N)NO ,解离得到产物HCN +NO ,这是最主要的通道之一 ;HC插入NO键 ,克服 38.9kJ/mol的势垒 ,产生富能的中间体HC(O)NN ,预测了五个反应通道 ,其中主要反应通道为 :NN +HCO .     

CCN与醇类分子的反应动力学

用266 nm的激光光解CCl3CN分子产生CCN自由基，并在室温(298 K)和腔体总压为1.33 kPa的条件下，利用激光诱导荧光技术研究了CCN( eX2|)自由基与一系列醇类分子CnH2n+1OH(n=1?6)的反应动力学，通过实时监测反应体系中CCN( eX2|)浓度随反应时间的变化，测量了这些反应的总包速率常数．这些数据均是首次报道．结果显示，CCN( eX2|)自由基与醇类分子的反应速率常数随着醇分子中C原子数的增加而增大，而且均大于CCN( eX2|)与相应C原子数的烷烃分子的反应速率常数．基于键解离能相关和线性自由能相关地讨论，CCN( eX2|)自由基与醇类分子的反应应是一个抽氢反应；受醇分子中OH基团的诱导效应的影响，醇分子C-H键上的H具有较大的活性，因而CCN( eX2|)自由基抽提C-H键上的H是主要的反应通道. 同时还利用碰撞络合物模型和成轨理论来讨论了长程吸引势对反应的指前因子的影响     

CX2(X=F, Cl, Br)与CH3CHO中C－C键插入和环加成的理论模拟

采用密度泛函[DFT]和自然键轨道理论[NBO]及高级电子耦合簇[CCSD(T)]和电子密度拓扑分析[AIM]方法, 研究了单重态二卤卡宾CX2(X=F, Cl, Br)与乙醛CH3CHO 中C—C键的插入反应及其环加成的反应机理. 在B3LYP/6-31G(d)水平上优化了各驻点构型, 用频率分析和内禀反应坐标法(IRC)对过渡态进行了验证, 计算了各物种的CCSD(T)/6-31G(d, p)单点能量. 用经Wigner校正的Eyring过渡态理论分别计算了1大气压下主反应通道的热力学与动力学性质, 并对反应通道中构型进行了自然键轨道及电子密度拓扑分析. 结果表明, CF2与CH3CHO反应的主产物是P2F[CH3CF2CHO: 插入CH3CHO中C-C键, 反应I(2)], 而CCl2及CBr2与CH3CHO反应的主产物是P1Cl[Cl2COCHCH3: 成环反应II(1)]及P1Br[Br2COCHCH3: 成环反应III(1)], 1大气压下, 反应I(2)和II(1)及III(1)进行的适宜温度范围分别为400~1300K和400~1000K.     

Rate Constants for Reaction Between Hydroxyl Radical and Dimethyl Sulfide Under Real Atmospheric Condition

用相对速率方法分别考察了OH自由基与DMS在氮气、空气和氧气体系的反应速率常数. 发现使用HONO和CH3ONO作为OH自由基发生剂时,基态氧原子O(3P)对动力学的测定有很大的影响. H2O2为OH自由基的发生剂,室温下在氮气、空气及氧气体系下的速率常数分别为4.50×10-12,8.56×10-12和11.31×10-12 cm3/(molecule?s).在287～338 K,测得氮气和空气体系下的阿累尼乌斯表达式分别为:kair=(7.24±0.28)×10-13exp[(770.7±97.2)/T],kN2=(3.40±0.15)×10-11exp[-(590.3±165.9)/T     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Hybrid Wavelength and Code Division Multiple Access in Optical Networks

A review of schemes for multiple access in fiber optic networks shows that a hybrid of wavelength and code division multiple access (WCDMA) combines the best features of both. In particular, the hybrid scheme retains the large information carrying capacity of wavelength division multiple access (WDMA) and flexibility of code division multiple access (CDMA). In this paper WDMA, optical CDMA (OCDMA), and WCDMA networks are discussed. In OCDMA networks, concept of incoherent and coherent coding including inverse decoding and matched filter is introduced. The delay performance of both WDMA and WCDMA networks, under the simple suboptimum access protocols based on cyclic search, is computed. It has been shown quantitatively that tuning delay significantly affects the delay performance of both WDMA and WCDMA networks. Futhermore, delay performance of WCDMA networks is always better than the WDMA networks for the same tuning delay, load, and number of users.     

Femtosecond Transform-Limited Pulse Generation by Compensating for the Linear Chirp of SPM Spectra in Dispersion Shifted Fibers

A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Theoretical analysis and simulation of conjugate heights for dual-conjugate AO system in lidar

A multi-conjugate adaptive optics （MCAO） can offer a possibility of widening field of view （FOV） characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle＇s expressions of two deformable mirrors （DMs） MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.     

Quick single-photon detector with many avalanche photo diodes working on the time division

Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.     

Research on beamforming method for dual-line array with space mismatch between the two line arrays

The performance of port/starboard discrimination of dual-line array will be seriously degraded when the space between the two line arrays of the dual-line array is mismatched. The directivity function of the delay-sum and delay-subtract beamforming is deduced and the port/starboard discrimination of the delay-sum and delay-subtract beamforming is also studied both under the ideal status and the status under which the space between the two line arrays of the dual-line array is mismatched. Analysis results show the delay-subtract beamforming has better performance of port/starboard discrimination. At last, the sea trial results demonstrate the theoretical results.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.