芳胺-二苯酮光化夺氢反应活泼自由基的ESR研究

本文用自由基捕捉剂与ESR相结合的方法系统研究了各种取代苯胺与二苯酮光化夺氢反应中的活泼自由基。找出了形成N-中心及C-中心自由基的条件:即当芳胺有N上氢和α-C上氢时,优先形成N-中心自由基;仅当无N上氢时,才形成C-中心自由基。     

C2（a 3Πu）+NO 的反应机理研究

在G2 (CC ,MP2 )理论水平上研究了C2 (a3 Πu)自由基与NO分子的反应 .计算了反应体系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反应机理 :由NO中的O原子进攻C2 自由基形成CCON中间体的CCON机理和NO中的N进攻C2 自由基形成CCNO中间体的CCNO机理 ,分析了对应与这两种反应机理的五个可能的反应通道 ,得出了由NO中的N原子进攻3 C2 自由基 ,生成中间体CCNO自由基 ,最终得到产物CN +CO的通道是最有利的通道 .     

C2（a^3Пu）＋NO的反应机理研究

在G2(CC，MP2)理论水平上研究了C2(a^3Пu)自由基与NO分子的反应．计算了反应体系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反应机理：由NO中的O原子进攻C2自由基形成CCON中间体的CCON机理和NO中的N进攻C2自由基形成CCNO中间体的CCNO机理，分析了对应与这两种反应机理的五个可能的反应通道，得出了由NO中的N原子进攻^3C2自由基，生成中间体CCNO自由基，最终得到产物CN+CO的通道是最有利的通道．     

N-溴代琥珀酰亚胺光解夺氢反应的ESR研究

本文用自旋捕捉剂亚硝基叔丁烷(MNP)和2,3,5,6-四甲基亚硝基苯与ESR相结合分别研究了N-溴代琥珀酰亚胺(NBS)光解反应产生的自由基,以及NBS与醇、取代芳烃及烷烃进行光解夺氢反应生成的活泼自由基中间体,结果表明:1.在紫外光用下,NBS分子中的N-Br键发生均裂,产生N-中心自由基并为MNP所捕获.2.对于醇及烷烃,NBS光解产生的Br能夺取叔碳原子上的氢,分别形成叔碳自由基HOR和R,并被ND所捕获.3.与烷烃及醇不同的是:Br不仅能夺取烷基取代苯分子中叔碳原子上的氢,而且还能夺取仲碳原子上的氢,分别形成自由基PhCR₂及PhCHR.     

N-取代酰胺-二苯酮体系光化夺氢反应活泼自由基的ESR研究

本文用自由基捕捉剂2,3,5,6-四甲基亚硝基苯(ND)及苯亚甲基叔丁基氮氧化物(PBN)与ESR相结合的方法研究了十二种取代酰胺RC₆H₄NHC(0)CH₃(R-CH₃、Cl、Br、H、NO₂)、C₆H₅N(R)C(0)CH₃(R=CH₃、C₂H₅)及HC(0)NR₂(R-CH₃、C₂H₅)与二苯酮光化夺氢反应中的活泼自由基。结果表明: 1.对于RC₆H₄NHC(0)CH₃,二苯酮夺取氮上H形成R-C₆H₄NC(0)CH₃自由基。 2.对C₆H₅N(R)C(0)CH₃及HC(O)NR₂,二苯酮夺取与羰基相连的甲基氢、羰基上氢及与N相连碳上的氢分别形成 C₆H₅N(R)C(0)CH₂、C(0)NR₂、C₆H₅N(CHR')C(0)CH₃及。     

γ射线与N离子辐照类金刚石薄膜的机理研究

对类金刚石 (以下简称 DLC)薄膜受 γ射线与 N离子辐照的结果进行了比较 .通过 Raman光谱分析得出 :γ射线辐照造成薄膜中 SP3C— H和 SP2C— H键的减少及 SP3C— C键的增加 ,与此同时氢原子结合成氢分子 ,并从膜中释出 ,薄膜的类金刚石特征更加明显.当辐照剂量达1 0×104Gy时 ,SP3C—H键减少了约 5 0 % .N离子辐照使 DLC薄膜中 SP3C— C键、SP2 C—H键及 SP3C—H键的含量均变少 ,并伴随着氢分子的释出 ,直接导致 DLC薄膜的进一步石墨化,其对 SP3C—H及 SP2C— H键的破坏程度远大于γ射线 .两者在辐照机理上截然不同.The results of the diamond like carbon films(the following is called for short DLC film) irradiated by γ rays and N ion were reported. It showed that SP 3C—H and SP 2C—H bonds were decreased, and SP 3C—C bonds were increased by γ ray irradiation, and induced hydrogen recombination with H 2 molecules, and subsequently released from the surface of the films. When the γ ray irradiation dose reached 10×104Gy, the numbers of SP3C—H bonds were decreased by about 50%...     

某些含氮有机物光催化氧化产生的自由基中间体

本文用自旋捕捉技术与ESR相结合的方法研究了某些含氮有机物TiO₂光催化降解的过程中形成的活泼中间体.选择的化合物中有丁胺、戊胺、庚胺、六氢吡啶、吡啶、2-甲基吡啶、2,6-二甲基吡啶,这些分子中的氮原子分别作为初级脂肪胺、饱和环中的二级胺以及芳环中的三级胺出现,实验中观察到N-中心自由基及C-中心自由基与自旋捕捉剂加合物的ESR信号,表明这些自由基参与这些化合物光降解的初始过程,对深入了解其光降机理是有意义的.     

氧氟沙星甲基化物的核磁共振波谱研究

结合1H NMR,13C NMR,DEPT,HSQC,HMBC谱和碳氟偶合裂分行为, 对氧氟沙星(ofloxacin, OFL)哌嗪部分的甲基化产物-甲基氧氟沙星(methyl-ofloxacin,Me-OFL)的结构进行归属,并探讨了Me-OFL在酸性及碱性溶液中的1H和13C谱的变化。碱性溶液中, 5H的化学位移较酸性向高场移动1.02, 推测此变化与形成C—H…O弱氢键有关。6C、13C、羰基碳7C和羧基碳15C分别向低场位移12.04,7.46,4.33,2.88 ppm, 推测此变化与羧基和羧酸根的转变有关。另外, 还比较了OFL哌嗪环4’N上质子化产物与烷基化产物的正电荷分布。当哌嗪环质子化形成季铵盐时,正电荷分布在氢原子上;当其烷基化形成季铵盐时, 正电荷分布在氮原子上。     

氮氢共掺杂金刚石中氢的典型红外特征峰的表征

所有天然Ia型金刚石红外光谱中都存在3107 cm-1特征峰,而在金属触媒直接合成的金刚石红外光谱中没有检测出3107 cm-1特征峰.本文在6.3 GPa,1500?C条件下,通过Fe70Ni30触媒中添加P3N5直接合成出具有3107 cm-1特征峰的氮氢共掺杂的金刚石.红外光谱分析表明,合成的金刚石中氢有两种存在形式:一种对应着乙烯基团C=CH2中C—H键的伸缩振动(3107 cm-1)和弯曲振动(1450 cm-1)的吸收峰,另一种对应着sp3杂化C—H键的对称伸缩振动(2850 cm-1)和反对称伸缩振动(2920 cm-1)的吸收峰.通过分析发现,3107 cm-1吸收峰与金刚石中聚集态的氮原子有关,当金刚石中没有聚集态的氮元素时,即使氮含量高也不会出现3107 cm-1峰;并且2850和2920 cm-1附近的吸收峰比3107 cm-1附近的吸收峰更为普遍存在.这说明sp3杂化C—H键比乙烯基团的C—H键更广泛存在于金刚石中,从两者的峰值看,天然金刚石中的氢杂质主要以乙烯基团C=CH2存在.3107 cm-1吸收峰与聚集态的氮原子的这种存在关系为天然金刚石形成机制的研究提供了一种新思路,同时较低的合成条件也可能为氢与其他元素共掺杂合成具有n型半导体特性的金刚石提供一个较理想的合成环境.     

偕胺肟纤维与Fe(Ⅲ),Co(Ⅱ),Ni(Ⅱ),Cd(Ⅱ),Hg(Ⅱ)配合物的红外光谱研究

用聚丙烯腈纤维 (PAN)改性制备的偕胺肟纤维 (AOCF)分别与三氯化铁、氯化钴、氯化镍、氯化镉和氯化汞在酸性介质中反应 ,制备偕胺肟 铁 (Ⅲ )、偕胺肟 钴 (Ⅱ )、偕胺肟 镍 (Ⅱ )、偕胺肟 镉 (Ⅱ )和偕胺肟 汞 (Ⅱ ) 5种偕胺肟 重金属配合物 (用通式M AOCF表示 )。用红外分光光度计分别对偕胺肟纤维和 5种配合物在 4 0 0 0～ 4 0 0cm- 1 范围进行傅里叶变换红外吸收 ,对各M AOCF的FTIR主要吸收峰做了经验归属 ,并将各M AOCF的特征吸收峰与AOCF的相应吸收峰作对比分析 ,结果表明 :配合物中C—N ,CN ,N—O等键的吸收峰位置均向高波数方向移动 ,且峰的强度增加。说明纤维材料中的偕胺肟基团与重金属离子在酸性介质中进行了配位反应 ,偕胺肟基团与重金属离子之间形成了配位键。     

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.