激光诱导荧光确定NiB自由基一个新的电子激发态：在19000-22100 cm -1的2II态

Ni针放电产生的Ni原子与B₂H₆反应产生NiB自由基,得到了在19000～22100 cm^-1的激光诱导荧光光谱. 通过对激光诱导荧光激发谱和色散谱的研究,发现了一个新的电子跃迁序列[20.77]²II-X²∑⁺,序列共包括11个振动谱带,光谱分析得到了这个新的电子激发态和基态的跃迁寿命. 在光谱常数和跃迁寿命等数据的基础上,讨论了新发现电子激发态的电子构型.     

硫化镍激光诱导荧光光谱：一个新的低激发态

采用激光诱导荧光技术在12200～13550 cm^-1能量范围内研究了超声射流冷却下的硫化镍光谱. 获得了4个具有转动结构的振转带,并被归属为基态至低激发态[12.4]³∑₀^- 的跃迁. 通过转动分析,确定了该低激发态的转动常数、同位素位移以及分子(平衡)常数. 此外,还测量了这些振转带的寿命.     

BeCl分子电子激发态的多参考组态相互作用计算

运用含Davidson修正的多参考组态相互作用方法,在aug-cc-pVTZ基组水平上,对BeCl分子基态和相同多重度的几个低电子激发态进行了势能扫描计算.通过群论原理确定各电子态对称性及离解极限.将其中基态(X²Σ⁺)和第一激发态(A²Π})对应的势能曲线拟合到Murrell-Sorbie解析势能函数形式,得到基态(X²Σ⁺)的离解能及主要光谱常数(括号中为文献[6]提供的实验值)为D_e=3.74eV,R_e=0.18173nm(0.17970),w_e=857.4cm¹(847.2),w_ex_e=5.03cm^-1(5.14),B_e=0.7103cm^-1(0.7285),α_e=0.0059cm^-1(0.0069),第一激发态(A²Π)的D_e=3.02eV,R_e=0.18369nm(0.18211),w_e=832.7cm^-1(822.1),w_ex_e=5.93cm^-1(5.24),B_e=0.6953cm^-1(0.7094),α_e=0.0065cm^-1(0.0068),计算结果与实验值符合得较好.另外,通过Level程序求解双原子径向核运动的Schrödinger方程得到J=0时BeCl分子这两个电子态的全部振动能级.     

11Be的结构

在粒子-振动模型(PVM)的基础上研究了¹¹Be核的基态特性、低激发态和电偶极跃迁,理论结果与实验符合很好.计算结果表明,¹¹Be的基态是单核子运动与核芯¹⁰Be的表面集体振动相耦合的结果.¹¹Be的晕结构也得到合理的解释.     

对氯氟苯S0, S1和D0态的实验与理论研究

本文采用共振增强多光子电离和慢电子速度成像技术研究了对氯氟苯(p-ClFPh)在中性第一激发态和阳离子基态下的几何结构和振动频率. 给出了对氯氟苯S₀态的红外光谱和S₁←S₀跃迁的吸收光谱. 基于单色、双色共振增强双光子电离技术，得到了对氯氟苯的跃迁激发能是36302±4 cm^-1. 通过阈值电离测量，外推得到对氯氟苯的绝热电离能为72937±8 cm^-1. 此外，通过Franck-Condon模拟，确定了S₁和D₀态的主要振动模式，并分析了对氯氟苯分子S₀&S₁和S₁&D₀跃迁过程中的Duschinsky振动模式混合效应.     

NaK低激发态光谱性质和辐射寿命的从头算

本文对NaK的电子结构做了高级从头算. 计算了与三个最低解离极限相关的10个?-S态的势能曲线. 基于计算的势能曲线,得到了束缚?-S态的光谱常数,与实验结果吻合较好. 用半经典散射理论分析了单重态基态X¹Σ⁺和三重态基态a³Σ⁺的最大振动量子数. 研究了包括跃迁偶极矩、夫兰克-康登因子和辐射寿命在内的跃迁特性. 研究结果表明,这种计算方法可以为超冷碱双原子分子实验提供较为可靠的参数估计.     

μ-介子在Be7原子核上的俘获

利用考虑到重正化效果的普适V-A理论,本文计算了μ^-被Be⁷俘获后跃迁到Li⁷的基态与第一激发态的俘获几率,Li⁷核第一激发态的极化,以及由此跃迁到其基态时放出γ光的偏振度,其中对于不同的超精细结构态分别进行了计算,计算过程中,采用了壳层模型的原子核波函数。并假定忽略二次效应下,S态的四个核子没有参加作用。     

ZrO-双原子阴离子的光电子成像谱

利用激光溅射制备了ZrO^-双原子阴离子,测量了其光电子成像谱．实验观测到的光电子能谱可以在光学光谱和高精度从头计算的基础上得到很好的归属．ZrO^-的基态确定为²△态,其自旋-轨道分裂能为578±12 cm^-1,ZrO的电子亲和能测定为1.249±0.005 eV．第一次在实验上观测到ZrO的c³∑^-激发态,其相对于X¹∑⁺基态的能量为13316±24 cm^-1,同时还对ZrO与其等电子体NbN的电子结构进行了比较．     

飞秒时间分辨拉曼光谱用于研究β-胡萝卜素单重激发态内转换和振动弛豫过程

搭建了飞秒时间分辨受激拉曼光谱(FSRS)装置，并用于研究全反式β-胡萝卜素单重电子激发态超快内转换和振动弛豫过程.基于三脉冲“抽运-探测”方案搭建的时间分辨受激拉曼光谱装置同时实现了150fs的时间分辨率和23.7cm^-1的光谱分辨率，光谱检测范围为300—4000cm^-1.对全反式β-胡萝卜素电子激发态的飞秒时间分辨拉曼光谱研究表明，β-胡萝卜素被激发到S₂态后，经由寿命约为0.3ps的中间态S_X态实     

Improved Calculation of Vibrational Energy Levels in F2 Molecule using the RKR Method

采用Hulburt和Hirschfeler势能函数,把利用Ryderg-Klein-Rees方法建立的氟分子基态势能曲线外推到整个的分子离解区间. 在外推法所建立的势能曲线的基础上求解氟分子的径向薛定谔方程,获得了最高振动量子数为22的各级振动能级. 各个振动能级分别与实验值进行比较,其平均绝对偏差约为7.6 cm^-1,计算所得的相对势能曲线最低点的离解能与其实验值13408.49 cm^-1的相对偏差约为0.74%.用本方法计算得到的氟分子基态的势能曲线和离解能比Bytautas用量子力学从头算方法得到的值更接近于实验值,也更准确.     

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.