氯与甲烷和重氢甲烷反应的矢量相关研究

在扩展的London-Eyring-Polanyi-Sato(LEPS)势能面基础上,利用准经典轨线法在碰撞能Ecol=3.67 kcal/mol下研究了Cl+CH4→HCl+CH3和Cl+CD4→DCl+CD3反应,在质心系计算得到四个广义极化微分反应截面((PDDCS)(2π/σ)(dσ00/dωt)、(2π/σ)(dσ20/dωt)、(2π/σ)(dσ22+/dωt)、(2π/σ)(dσ21-/dωt)和k-k′-j′三矢量相关的极角分布p(фr)、k-j′两矢量相关的p(θr)分布以及用θr和фr表示的产物转动角动量的空间分布.计算结果与有关实验及理论结果符合得很好,讨论了氯与甲烷和重氢甲烷反应的立体动力学同位素效应.     

Mn激活无水芒硝在真空紫外光激发下的发光特性

在空气中900℃温度下,将纯天然无水芒硝(Na2SO4)和MnCl2的混合粉末900℃加热20 min后,迅速骤冷至室温制备了Na2SO4∶Mn发光材料,并测量了其在室温中真空紫外光激发下的光致发光谱.实验结果表明,在172 nm激发下的发射光谱由峰值位于在592 nm处的宽带谱构成,所得到的宽带谱归属于Mn2+的3d...     

CH3CH2+N(4S)反应机理的理论研究

利用abinitio方法对CH3CH2+N(4S)反应进行了理论研究,在MP2/6-311+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)/6-311+G(d,p)水平上进行单点能计算.计算结果表明,CH2CH2+3NH和H2CN+CH3是此反应主要产物,CH3CHN+H是此反应次要产物.产物CH2CH2+3NH主要来自直接氢抽提反应通道,H2CN+CH3来自加成-解离反应通道,CH3CHN+H来自加成-解离反应通道.     

Dy3+激活无水芒硝在真空紫外光激发下的发光性质

在空气中900℃温度下,将纯天然无水芒硝( Na2 SO4)和DyF3的混合粉末加热25 min,制备了Na2SO4:Dy3+新型发光材料.通过同步辐射研究了NaSO4:Dy3+的发光性质.并测量了在室温中真空紫外-紫外光下的发射和激发光谱.根据发射光谱得到了不同Dy3+掺杂浓度和不同激发下发光的黄蓝比(Y/B)是不同的.通过监测黄色发光得到的激发光谱,分别由Dy3+,4f9→4f85d跃迁(172 nm)、O2--Tm3+之间的电荷转移带(165 nm)引起的强激发谱和基质吸收(138,245 nm)、对应Dy3+,6 H15/2→4 D7/2,6H15/2→6 P3/2,6 H15/2→6P7/2跃迁(299,325,351nm)引起的弱激发谱组成.     

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.     

四-(对-羧基苯基)卟啉在水/三氟乙酸溶液中J-聚集的光谱研究

本文研究了四-(对-羧基苯基)卟啉(TCPP)在H2O/CF3COOH、H2O/CCl3COOH和H2O/CH3COOH溶液中的UV-Vis吸收光谱、荧光光谱和拉曼光谱.实验表明,TCPP在H2O/CH3COOH和H2O/CCl3COOH溶液中以分子态的N-质子化卟啉H8TCPP2+存在,而在H2O/CF3COOH中则形成H8TCPP2+的J-聚集体.J-聚集体显示,UV-Vis吸收光谱和荧光光谱的谱带明显红移.拉曼光谱表明,J-聚集体中H8TCPP2+分子的排列与N-质子化四-(对-磺酸基苯基)卟啉H4TSPP2-的J-聚集体相似.     

Tm3+激活无水芒硝在真空紫外光激发下的发光性质

采用高温固相反应方法在空气中制备了Na2SO4:Tm2+发光材料.用X射线衍射对晶体结构进行了表征.发射光谱由Tm3+内4f12电子跃迁的窄峰组成.激发光谱分别由Tm3+离子4f12→4f115d跃迁(183nm),O2--Tm3+之间的电荷转移带(170 nm)引起的强激发谱和基质吸收(130,223,258 nm)...     

乙醚-水混合团簇的多光子电离质谱及从头算

应用多光子电离技术结合飞行时间质谱仪对乙醚与水的混合团簇进行了研究,实验中观测到了多个序列的质子化团簇： (CH3CH2OCH2CH3)nH+（n=1、2…6）、(CH3CH2OCH2CH3)nH2OH+（n=1、2…4）和(CH3CH2OCH2CH3)n(H2O)2H+ （n=2、3、4）。通过对质谱的研究发现,(CH3CH2OCH2CH3)3H2OH+为幻数结构。结合从头计算理论,在B3LYP/6-31G(d)基组水平上对乙醚与水混合团簇的可能构型进行优化,得到了其稳定构型。振动频谱分析显示,团簇中最强的红外振动模式主要来自氢键中H的伸缩振动的贡献。     

氯与甲烷和重氢甲烷反应的矢量相关研究

在扩展的London?Eyring?Polanyi?Sato(LEPS)势能面基础上,利用准经典轨线法在碰撞能Ecol=3.67 kcal/mol下研究了Cl CH4→HCl CH3和Cl CD4→DCl CD3反应,在质心系计算得到四个广义极化微分反应截面((PDDCS)(2π/σ)(dσ00/dωt)、(2π/σ)(dσ20/dωt)、(2π/σ)(dσ22 /dtω)、(2π/σ)(dσ21-/dωt)和k-k′-j′三矢量相关的极角分布p(r)、k-j′两矢量相关的p(rθ)分布以及用θr和r表示的产物转动角动量的空间分布.计算结果与有关实验及理论结果符合得很好,讨论了氯与甲烷和重氢甲烷反应的立体动力学同位素效应.     

槲皮素-Sn(II)配合物荧光、紫外及红外光谱的测量与分析

以NH4Cl-NH3.H2O为缓冲液,十六烷基三甲基溴化铵(CTAB)为荧光增强剂,用荧光分光光度计分别采集槲皮素、槲皮素-Sn(II)配合物溶液、槲皮素-Sn(II)-NH4Cl-NH3.H2O、槲皮素-Sn(II)-NH4Cl-NH3.H2O-CTAB溶液以及将其溶液分别静置7h和21h后的荧光光谱,并对光谱进行分析。在不加CTAB的条件下,用紫外分光光度计分别测量加入缓冲液前后的紫外光谱。用漫反射方法测定配合物的红外光谱,并对其结构进行初步分析。在缓冲液的作用下,槲皮素-Sn(II)配合物的结构发生了变化;通过分析,发现与缓冲液发生反应的主要基团为酚羟基,红外光谱中酚羟基的消失和NH4+基团的出现,说明了配合物中的酚羟基与NH4+发生了取代反应。     

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.     

Characterization of PolyA and PolyC mismatches by Raman spectroscopy

A.C mismatches are studied by Raman spectral characterization of PolyA, PolyC, and their equimolar complex in solution of 0.14 mol/L Na ,pH7.0.Experimental results show that A·C mismatches occur to be A/B (mainly A) conformers, and unlike Watson-Crick base pairing, this kind of mismatches is stabilized by only one hydrogen bond involving cytosine N4H2 and adenine N7.The formation of A·C complex makes the base stacking interactions much stronger, and conformation of the backbone more ordered, which leads to obvious Raman hypochromic effect with some shifts in corresponding bands.     

Improvement of four-wave mixing-based wavelength conversion efficiency in dispersion shifted fiber by 40-GHz clock pumping

40-GHz clock modulated signal as a pump to improve the efficiency of four-wave mixing (FWM)-based wavelength conversion in a 26.5-km dispersion shifted fiber (DSF) is investigated. The experimental results demonstrate that the conjugated FWM component has higher intensity with the clock pumping than that with the continuous-wave (CW) light pumping. The improvement of FWM-based wavelength conversion efficiency is negligible when the pump power is less than Brillouin threshold. But when the pump power is greater than Brillouin threshold, the improvement becomes significant and increases with the increment of pump power. The improvement can increase up to 9 dB if pump power reaches 17 dBm.     

Multi-pulse operation of a Kerr-lens mode-locked femtosecond laser

Our experimental results show that the presence of a proper amount of negative group velocity dispersion is essential to multi-pulse operation of a Kerr-lens mode-locked femtosecond laser. We demonstrate that the pulse separations and the number of pulses contained within a cavity round trip are strongly dependent on the initial perturbations. The results allow us to get a better understanding on the influences of the convoluted self-phase modulation and intra-cavity dispersions on the stable multi-pulse oscillation in a Kerr-lens mode-locked femtosecond laser.     

Propagation of Helmholtz-Gauss beams in weak turbulent atmosphere

Based on the Rytov approximation of light propagation in weak turbulent atmosphere,the closed-form expressions of field and average irradiance of each one of the four fundamental families of Helmholtz-Gauss (HzG)beams:cosine-Gauss beams,stationary Mathieu-Gauss beams,stationary parabolic-Gauss beams,and Bessel-Gauss beams,which are propagating in weak turbulent atmosphere,are obtained.The results show that the field and average irradiance can be written as the product of four factors:complex amplitude depending on the z-coordinate only,a Ganssian beam.a factor of complex phase perturbation induced by atmospheric turbulence,and a complex scaled version of the transverse shape of the non-diffracting beam.The effect of weak atmospheric turbulence on irradiance distribution of the HzG beam can be ignored.     

An effective method for reducing speckle noise in digital holography

An effective method for reducing the speckle noise in digital holography is proposed in this paper.Different from the methods based on classical filtering technique,it utilizes the multiple holograms which are generated by rotating the illuminating light continuously.The intensity images reconstructed by a series of holograms generated by rotating the illuminating light possess different speckle patterns.Hence by properly averaging the reconstructed intensity fields,the speckle noises can be reduced greatly.Experimental results show that the proposed method is simple and effective to reduce speckle noise in digital holography.     

Influence of purity of HfO2 on reflectance of ultraviolet multilayer

The impurities in two kinds of HfO2 materials and in their corresponding single layer thin films were determined through glow discharge mass spectrum technology and secondary ion mass spectrometry(SIMS) equipment respectively.It was found that ZrO2 was the main impurity in the two kinds of HfO2 either in the original HfO2 materials or in the electron beam deposited films.In addition,the difference of Zr content in the two kinds of HfO2 single laver films was much laxger than that of the other impurities such as Ti and Fe.which showed that it was just ZrO2 that made the difference between the optical performance of the film products including the two kinds of HfO2.With these two kinds of HfO2 and the same kind of SiO2.we deposited HfO2/SiO2 multilayer reflective coatings at the wavelength of 266 nm.Experimental results showed that the reflectances of these two mirrors were about 99.85% and 99.15% respectively,which agreed well with the designed results what were based on the optical constants obtained from the corresponding single layer thin films.     

Speech enhancement by array crosstalk resistant ANC and spectrum subtraction

Microphone array-based speech enhancement has great importance for speech communications and speech recognition. To reduce the aperture of the microphone array and to increase the effect of the speech enhancement will greatly broaden the application areas of the microphone array. An array crosstalk resistant adaptive noise cancellation method is therefore presented. And then an improved spectral subtraction algorithm is further cascaded to obtain better enhancement results. Theoretic analysis and experiments indicate that the proposed scheme needs only a very small microphone array while it simultaneously achieves a higher SNR improvement. Besides, the proposed scheme can be used in many noisy environments and is easy for real-time implementation.