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.     

氧化镍位于510～610 nm的激光诱导荧光光谱 (cited: 1)

采用激光诱导荧光技术在510～650 nm研究了超声射流冷却下的氧化镍光谱,观测了55个振转谱带. 通过转动分析发现激发态的同位素位移、振转间隔和转动常数都表现出高度的不规则性,26个[Ω=0,1]-X³∑^-₀的跃迁谱带被暂时归属为5个振动序列. 此外实验中还观测了部分谱带的色散谱和寿命.     

光腔衰荡光谱研究PH2自由基在465-555 nm的光谱

采用光腔衰荡光谱记录了465-555 nm范围内PH₂自由基在射流冷却条件下的吸收光谱. 在超声射流条件下对氩载气中的PH₃和SF₆混合物直流放电产生PH₂自由基. 得到了7个有精细转动结构的振转谱带,并归属为PH₂自由基?²A₁- Χ²B₁电子跃迁的0⁰₀、2ⁿ₀、2ⁿ₁ (n=1-3)跃迁. 在已有的基础上,重新归属每一个振转谱带的转动量子数和转动项值;进一步精细化转动常数、离心畸变常数和自旋转动相互作用常数. 另外还简单讨论了每个K结构受到其它电子态的微扰.     

15N216O在1650-3450 cm-1的高分辨红外光谱

采用傅里叶变换红外光谱仪记录了富含¹⁵N₂¹⁶O同位素的一氧化二氮样品在1650-3450 cm^-1波段的高分辨振转光谱,得到了该同位素分子超过7300吸收谱线位置的实验值,经分析实验精确度好于5.0×10^-4 cm^-1. 基于有效哈密顿量模型预测和带带转动分析,确定了所有吸收线的归属;获得了29个新吸收带的振转光谱参数,并优化了其他44个吸收带的光谱参数值. 并且发现有效哈     

Cl2+离子R支跃迁光谱的理论研究

从双原子分子能级的物理表达式出发进行多次微分,建立了预测双原子分子体系R支高振转跃迁谱线的新解析公式. 使用新解析公式预测双原子体系R支高阶跃迁谱线的数据时,最多只需15条精确的实验跃迁谱线和该跃迁带中对应的上下 振动态的转动光谱常数B′_v 和 B″_v.将该解析公式用于预测Cl₂⁺ 离子 A²∏_u---X²∏_g跃迁系(3,7)带和(4,8)带的跃迁谱线,不仅精确的重复了实验给出的较低阶的跃迁光谱数据值, 而且正确预言了所研究体系中缺失的振转跃迁谱线,尤其是高阶的跃迁谱线数据.     

稀土区高自旋三轴超形变及其形成机制

通过¹⁵²Sm(¹⁹F,4n)¹⁶⁷Lu反应观测到¹⁶⁷Lu的一个新的转动带.发现其高自旋γ跃迁能量与¹⁶³Lu和¹⁶⁵Lu三轴超形变的十分相近.按基于推转壳模型的总转动位能面计算,¹⁶⁷Lu和前人工作中的¹⁷¹Ta[660]1/2转动带被指定为三轴超形变带.讨论了该核区三轴超形变的形成机制.     

162Lu的高自旋态及A=160区双奇核晕态能级的符号因子反转

利用¹⁴⁷Sm(¹⁹F,4nγ)¹⁶²Lu反应研究了¹⁶²Lu的高自旋态. 由7个带BGO康普顿抑制的高纯锗探测器和一个小平面探测器进行了在束γ测量,首次建立了双奇核¹⁶²Lu转晕带的能级纲图. 发现在低转动频率下,¹⁶²Lu的转晕带能级发生符号因子反转. 对质量数A=160核区双音核的转晕带重新进行了分析和考察,讨论了转晕带能级符号因子反转的系统性.     

缺中子核素125,127,129Ce的转动结构

用组态相关推转Nilsson-Strutinsky方法研究了缺中子核素^125,127,129Ce的转动结构性质, 讨论了转晕带的旋称劈裂和核的形状. 转晕带相应的核形状均是近轴对称的. ^127,129Ce在同一个组态中可能有形状共存. 理论指出即使对于无三轴形变核也有可能出现较大的旋称劈裂.     

用从头算方法研究GeCl2分子的非谐振力场和光谱常数

用从头算方法的MP2和CCSD（T）方法结合cc-pVTZ基组计算了二氯化锗同位素（⁷⁰GeCl₂、⁷²GeCl₂和⁷⁶GeCl₂）分子的平衡结构、光谱常数和非谐振力场.二氯化锗的几何结构、转动常数、振转相互作用常数、谐频、非谐振常数、四次和六次离心畸变常数、三次和四次力常数的计算结果与实验结果符合较好,二氯化锗分子的同位素效应较小,可能的原因是Ge同位素的质量变化相对较小.两种方法计算的结果均与实验结果符合,但CCSD（T）方法比MP2计算结果的偏差稍大一些,可能的原因是CCSD（T）方法在描述过共价Cl原子的电子相关时不够充分.     

BF自由基X1∑+和a3∏态光谱常数和分子常数研究

采用内收缩多参考组态相互作用方法和相关一致基aug-cc-pV6Z, 对BF自由基X¹∑⁺和a³∏ 态的势能曲线进行了研究. 计算是在0.095---1.33 nm的核间距内进行的. 为获得更准确的结果, 计算中还考虑了Davidson修正、相对论修正及核价相关修正对势能曲线的影响. 相对论修正采用的方法是二阶DouglasKroll哈密顿近似, 修正计算是在cc-pV5Z基组水平上进行的. 核价相关修正使用的是cc-pCV5Z基组. 利用得到的势能曲线, 拟合出了各种修正下BF自由基X¹∑⁺和a³∏ 态的光谱常数D_e, R_e, ω_e, ω_ex_e, ω_ey_e, B_e和α_e、并与实验结果进行了比较. 结果表明: 考虑Davidson修正、相对论修正和核价相关修正后得到的光谱常数最接近实验结果. 利用修正后的势能曲线, 通过求解径向振转Schrödinger方程, 找到了转动量子数J = 0时这两个电子态的全部振动态, 并计算了每一电子态前20个振动态的振动能级、惯性转动常数和离心畸变常数, 其值与已有的实验结果较为一致. 本文得到的光谱常数和分子常数达到了很高的精度, 能为进一步的光谱实验提供可靠的参考.     

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.