UO2体系的分子动力学研究

基于多体展式方法所导出的ＵＯ２（Ｚ＾３Σu＾＋）分析势能函数,用准经典的Ｍｏｎｔ ｅ－Ｃａｒｌｏ轨迹法研究了Ｏ（Ｘ＾３Ｐｇ）＋ＵＯ（０,０）的原子与分子反应动力学过程。研究结果表明：Ｏ（Ｘ＾３Ｐｇ）与ＵＯ（０,０）碰境生成稳定络合物ＵＯ２（Ｘ＾３Σｕ＾＋）,该反应是无阈能反应;而Ｕ（Ｘ＾５Lu）与Ｏ２（０,０）碰撞不能生成稳定络合物,主要发生交换反应：Ｕ（Ｘ＾５Ｌu）＋Ｏ２（０,０）→ＵＯ（Ｖ＾１,Ｊ     

He（2^3S）与N2O（X）Penning电离中的N2O^＋（A^2Σ^＋）生成速率及相…

在分子束条件下测量了Ｈｅ（２＾３Ｓ）＋Ｎ２Ｏ（Ｘ）→Ｎ２Ｏ＾＋（Ａ＾２Σ＾＋）＋Ｈｅ（＾１Ｓｏ）＋ｅ＾－反应的Ｐｅｎｎｉｎｇ电离光学光谱，求得了Ｎ２Ｏ＾＋（Ａ＾２Σ＾＋）态的初生态相对振动布居。以Ｈｅ（２＾３Ｓ）＋Ｎ２（Ｘ）→Ｎ＾＋２（Ｂ＾２Σ＾＋ｕ）＋Ｈｅ（＾１Ｓｏ）＋ｅ＾－为参考反应，测量了Ｈｅ（２＾３Ｓ）＋ＢＮ２Ｏ＾＋（Ａ＾２Σ＾＋）＋Ｈｅ（＾１Ｓｏ）＋ｅ＾－反应的速率常数ＫＮ２Ｏ＾＋（Ａ）     

NO2体系的分子动力学研究（二）

基于多体展式方法所导出的ＮＯ２（Ｘ２Ａ１）的分析势能函数［１］，用准经典的Ｍｏｎｔｅ－Ｃａｒｌｏ轨迹法研究了Ｏ（３Ｐｇ）＋ＮＯ（Ｘ２ＩＩ）和Ｎ（３Ｄｕ）＋Ｏ２（Ｘ３∑－ｇ）的原子与分子反应动力学。研究结果指出，反应Ｏ（３Ｐｇ）＋ＮＯ（Ｘ３ＩＩ）→ＮＯ２（Ｘ２Ａ１）的阈能值约为２ｋｃａｌ／ｍｏｌ，而反应Ｎ（２Ｄｕ）＋Ｏ２（Ｘ３∑－ｇ）→ＮＯ（Ｘ３ＩＩ）＋Ｏ（３Ｐｇ）是无阈能的。对后者，随初始平动能的增加，反应产物的向前散射减少，在１６０ｋｃａｌ／ｍｏｌ时达到极小，之后又缓慢增加。     

N（4Su）＋CH）（a^4Σ^—）体系的分子反应动力学研究

用轨线法对Ｎ（＾４Ｓｕ）＋ＣＨ（０,０）→ＣＮ（ｖ＇,Ｊ＾＇）＋Ｈ（Ｓｇ）和Ｎ（＾４Ｓｕ）＋ＣＨ（０,０）→ＮＨ（ｖ＇,Ｊ＇）＋Ｃ（＾３Ｐｇ）反应进行计算,研究了上反应的阈能、反应截面、产物散射分析和微观反应机理。     

Br2 B^3П^＋Ou←X^1Σ^＋g共振简并四波混频光谱

我们把共振简并四波混频（ＤＦＷＭ）光谱技术用于Ｂｒ２Ｂ＾３П＾＋Ｏｕ←Ｘ＾１Σ＾＋ｇ光谱。Ｂｒ２的汽压为７０ｍＴｏｒｒ，脉冲激光能量６０微焦耳，共振简并四波混频光谱线宽０．０３ｃｍ＾－１。     

自由基和激发态原子分子反应装置

自由基和激发态原子分子反应装置是一台综合了分子束技术，激光诱导荧光技术，共振多光子电离技术及质谱和化学发光光谱测量技术相结合的功能比较齐全的分子反应动力学研究装置。利用稀有气体（Ｈｅ，Ａｒ，Ｘｅ）亚稳态与Ｎ２，ＣＳ２等分子碰撞传能发射光谱测量及Ｃ（＾３Ｐ）＋Ｎ２Ｏ（Ｘ＾１Σ＾＋）反应产物ＣＮ（Ｘ＾２Σ＾＋，Ｖ＾ｎ）的激光激发谱测定证实了这台装置具有良好的工作性能。并将装置分为超音束源，质谱室及激光     

UO2分子的多体项展式势能函数

采用Ｇａｕｓｓｉａｎ９４ Ｗ 程序和相对论有效原子实理论模型优化出ＵＯ２ 分子稳定构型为线性Ｏ—Ｕ—Ｏ（ Ｄ∞ｈ） ,亚稳定构型为Ｕ—Ｏ—Ｏ（ Ｃ∞ｖ） ,计算出平衡核间距和振动频率．然后根据微观可逆性原则,准确地判断了ＵＯ２ 分子的离解极限．运用多体项展式理论方法,导出了基态ＵＯ２ 分子的分析势能函数,绘出其势能面等值图,准确地展现了Ｏ—Ｕ—Ｏ（ Ｄ∞ｈ） 稳定结构和Ｕ—Ｏ—Ｏ（ Ｃ∞ｖ） 亚稳定结构,根据势能面等值图讨论了Ｏ（３Ｐｇ） ＋ ＵＯ 反应和Ｕ＋ Ｏ２（ Ｘ３Σ－ｇ ） 反应的势能面静态特征     

铁酸盐的水热氧化晶化法制备及其生成条件研究

研究了空气氧化Ｍ＾２＋（Ｍ＝Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉ）和Ｆｅ＾２＋的碱性悬浮液制备铁酸盐ＭＦｅ２Ｏ４的条件，考察了原料配比、ｐＨ值、氧化温度、氧化时间对生成ＭＦｅ２Ｏ４的影响。利用ＸＲＤ及ＳＥＭ检测氧化过程中沉淀物的形态和结构表明，在３４３￣３５８Ｋ和Ｒ＝２ＯＨ＾－／（Ｍ＾２＋Ｆｅ＾２＋）＝１．０、Ｍ＾２／Ｆｅ＾２＋＝０．５（摩尔比）下用３００ｍＬ／ｈ的空气氧化Ｍｘ／３Ｆｅ１－ｘ／３（ＯＨ）２悬浮液     

U^＋＋的能级与UO^＋＋2的电子状态

用全相对论量子力学方法计算了电子组态为［Ｒｎ］５ｆ２６ｄ１７ｓ１的Ｕ的全部２１４个电子状态的能级，基态为５Ｋ５。设ＵＯ２为线型（Ｒ∞ｈ），Ｕ和Ｏ２均为基态，则ＵＯ２的可能电子状态有３，５，７Σ－ｇ，３，５，７πｇ，…。ＵＯ２的基态不大可能为１Σ＋ｇ。     

直接激光气化产生水溶剂化的氧化镁团簇

用飞行时间质谱仪探测了直接激光气化碱式碳酸镁样品产生的质谱，结果表明：氧化镁团簇与同时产生的水分子发生了原位溶剂化反应并产生了各种尺寸的溶剂化氧化团簇离子，这些团簇离子包括：（Ｍｇ（Ｈ２Ｏ）ｍ）＾＋（ｍ＝０，１，２，３），（Ｍｇ（ＭｇＯ）Ｈ２Ｏ）ｍ（ｍ＝１，２，３，４）（Ｈ（ＭｇＯ）（Ｈ２Ｏ）ｍ）＾＋（ｍ＝０，１，２，３，４，５，６），（Ｈ（ＭｇＯ）２（Ｈ２Ｏ）ｍ）＾＋（ｍ＝０，１，２，３，４，５     

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.