LiO2(C2V，X2A2)分子的结构与势能函数

使用二次组态相互作用方法，在aug-cc-pvtz基组水平上对LiO₂(C_2V，X²A₂)基态分子进行了几何优化，得到了它的平衡几何构型和力常数.根据原子分子反应静力学原理得到可能的电子状态和离解极限.应用多体展式理论方法推导出了LiO₂(C_2V，X²A₂)基态分子的解析势能函数.     

Regarding the axial-vector mesons

The implications of the f₁(1285)-f₁(1420) mixing for the K₁(³P₁)- K₁(¹P₁) mixing angle are investigated. Based on the f₁(1285)-f₁(1420) mixing angle ∼ 50^° suggested from the analysis for a substantial body of data concerning the f₁(1420) and f₁(1285), the masses of the K₁(³P₁) and K₁(¹P₁) are determined to be ∼ 1307.35±0.63 MeV and 1370.03±9.69 MeV, respectively, which therefore suggests that the K₁(³P₁)- K₁(¹P₁) mixing angle is about ±(59.55±2.81)^°. Also, it is found that the mass of the h^′₁(¹P₁) (mostly of sˉ) state is about 1495.18±8.82 MeV. Comparison of the predicted results and the available experimental information of the h₁(1380) shows that without further confirmation on the h₁(1380), the assignment of the h₁(1380) as the sˉ member of the ¹P₁ meson nonet may be premature.     

Spectroscopic investigations on NO+(x1∑+,a3∑+,A1Ⅱ) ion using multi-reference configuration interaction method and correlation-consistent sextuple b

Three low-lying electronic states (x¹∑⁺,a³∑⁺,and A¹Ⅱ) of NO⁺ ion are studied using the complete active space self-consistent-field (CASSCF) method followed by highly accurate valence internally contracted multi-reference configuration interaction (MRCI) approach in combination of the correlation-consistent sextuple basis set augmented with diffuse functions, aug-cc-pV6Z. The potential energy curves (PECs) of the NO⁺(x¹∑⁺,a³∑⁺,A¹Ⅱ) are calculated. Based on the PECs, the spectroscopic parameters R_e, D_e, ω_e, ω_eχ_e, α _e, B_e, and D₀ are reproduced, which are in excellent agreement with the available measurements. By numerically solving the radial Schrödinger equation of nuclear motion using the Numerov method, the first 20 vibrational levels, inertial rotation and centrifugal distortion constants of NO⁺(x¹∑⁺,a³∑⁺,A¹Ⅱ) ion are derived when the rotational quantum number J is equal to zero (J = 0) for the first time, which accord well with the available measurements. Finally, the analytical potential energy functions of these states are fitted, which are used to accurately derive the first 20 classical turning points when J = 0. These results are compared in detail with those of previous investigations reported in the literature.     

On the Absorption of antibaryons in nuclei

Antiproton (ˉp) and antilambda (ˉΛ) production has been measured for minimum bias in p+A collisions and central A₁+ A₂ collisions at the CERN-SPS by the collaborations NA35/49 and NA44. The measurements are extrapolated from rapidity distributions to absolute minimum bias cross sections. It is shown that the ˉp cross sections divided by A₁· A₂ follow an exponential trend as a function of a characteristic length obtained from a Glauber type absorption model, while the ˉΛ cross sections divided by A₁· A₂ are constant. The exponential trend also holds for ˉp production at the lower energies of the Brookhaven AGS. A discussion of the physics interpretation of the established trends in terms of an effective absorption cross section is presented. Received: 15 July 1999 / Revised version: 10 November 1999     

SiO2分子的基态(X1A1)结构与分析势能函数

应用群论及原子分子反应静力学方法推导了SiO₂分子的电子态及其离解极限，采用B3P86方法，在6-311G^**水平上,优化出SiO₂基态分子稳定构型为单重态的C_2V构型，其平衡核间距R_e=R_Si—O=0.1587 nm,∠OSiO＝111.2°,能量为-440.4392 a.u..同时计算出基态的简正振动频率:对称伸缩振动频率ν(B₂)=945.4cm^-1，弯曲振动频率ν(A₁)=273.5 cm^-1和反对称伸缩振动频率ν(A₁)=1362.9cm^-1.在此基础上，使用多体项展式理论方法，导出了基态SiO₂分子的全空间解析势能函数，该势能函数准确再现了SiO₂(C_2V)平衡结构.     

高分辨的一氧化二氮光解离实验研究

利用"时间切片"离子速度成像技术研究了N₂O分子在134.20、135.20和136.43 nm波长下的真空紫外光解动力学. 实验中通过采集解离产物O(¹S_J=0)的离子影像来研究O(¹S_J=0)+N₂(X¹∑_g⁺)这一解离通道. 从各个波长下的实验影像可获得产物N₂(X¹∑_g⁺)的振动态分辨的结构,进而得到产物的总平动能谱和产物N₂的振动态布居. 实验结果表明在实验的光解波长下,产物N₂(X¹∑_g⁺)主要布居在v=2和v=3. 此外,还得到了产物N₂的振动态分辨的各向异性参数β,从中发现产物N₂的β值在三个解离波长下均表现出相似的特征,即随着振动量子数的增大,β值从趋近于2逐渐减小至1.4. 这一现象表明低振动态产物是通过一个以平行跃迁解离为主的解离过程产生的,而高振动态的产物来自于一个更加弯曲的中间构型的解离. 此推论与在平动能谱中所见到的最强转动态布居随着振动量子数的增大而出现的位移是相一致的.     

多量子位Heisenberg XX链中的杂质纠缠

通过分析系统的杂质位与其余部分间的纠缠N_1-A以及单个正常位与其余部分间的纠缠N_L-A研究了匀强磁场作用下含杂质Heisenberg XX链的纠缠特性.研究表明三量子位时纠缠存在的临界温度依赖于杂质参数J₁和匀强磁场B.研究发现,当量子位L为奇数时,纠缠N_1-A随量子位的增加而增大,而L为偶数时则相反,并且量子位L为偶数时的纠缠大于量子位L为奇数时的纠缠;对N_L-A, 量子位L为奇数时,纠缠随杂质参数J₁的变化与L=3类似,而L为偶数时纠缠随杂质参数|J₁|的增加而增加.     

基于Fourier-Bessel级数的Bessel型超声场二次谐波近场特性研究

将Fourier-Bessel级数引入KZK方程的求解，用于计算黏滞媒质中零阶Bessel型超声场的二次谐波声场，得到其级数形式的解析解，并由此得出二次谐波声场在近场分布的一个新结论.设声源表面声压分布为J₀(α₀r)，则二次谐波声压在近场的径向分布服从J²₀(α₀r)函数规律.这一结论合理解释了相关的实验结果，表明二次谐波声场在近场和远场有不同的径向分布，从而解决了非线性Bessel型超声场二次谐波的近场分布问题.研究还发现二次谐波声场具有类似基波声场的有限衍射特性.给出了一个数值计算和仿真实例.     

Be9(d,p),(d,t),(d,a)反应研究

本文在E_d=0.1—2.5MeV能量范围内,研究了Be⁹(d,p₀)Be¹⁰(0),Be⁹(d,p₁)Be¹⁰(3.368MeV),Be⁹(d,t₀)Be⁸(0),Be⁹(d,α₀)Li⁷(0)及Be⁹(d,α₁)Li⁷(0.478MeV)诸反应。在E_d=0.150,0.220,0.401,0.706,1.005,1.301,1.484,1.750,2.000,2.250和2.500MeV共十一个能量上分别测量了这五群出射粒子在θ_L=10—155°区间的角分布。在θ_L=135°,E_d=0.1—2.5MeV,在θ_L=95°,E_d=0.1—2.2MeV,和在θ_L=112.5°,E_d=0.5—2.5MeV测量了Be⁹(d,p₀)Be¹⁰的激发函数。在θ_L=135°和112.5°,E_d=1.2MeV,用较厚靶(100—300μg/cm²)测量了Be⁹(d,p₀)Be¹⁰(0)反应的截面绝对值,结果为σ_(p0)(θ_L=135°)=1.60mb/sr,σ_(p0)(θ_L=112.5°)=1.55mb/sr。这样就得到了在此能区内,这五群出射粒子的截面情况。对所得结果进行了一些讨论。     

氮原子在800 nm附近的同位素位移

The Doppler-limited absorption spectra of ¹⁴N and ¹⁵N atoms were measured around 800 nm using concentration modulation spectroscopy to study their isotope shifts. The nitrogen atoms were generated by discharging molecular nitrogen buffered with helium in a homemade discharge tube. The isotope shifts of four multiplets (3s⁴P_J→3p⁴D_J^o, 3s⁴P_J→3p⁴P_J^o, 3s²D_J→5s²P_J^o, and 3p²P_J^o→5s²D_J^o) were measured and their J-dependent specific mass shifts were observed and discussed.     

二元光学液晶闪耀光栅的特性分析

在二元光学理论的基础上,结合波动光学理论和液晶指向矢的计算提出一种新的二元光学液晶闪耀光栅设计.对液晶光栅电极施加阶梯分布的电压使之形成相位阶梯形分布,推导出液晶闪耀光栅的衍射效率.结果表明,通过改变周期单元光栅电极数日而改变光栅常数,可以改变光衍射角度,一级衍射角度调节范围0°～10°;调节电极电压可以使特定级次衍射光效率达到90%以上,使该级次得到闪耀.     

液晶盒视角对比度曲线的实验测量

设计了一种测量液晶盒视角的实验装置,通过固定的水平角度和竖直角度扭曲向列相液晶盒光透过率的测量,得到了视角-对比度曲线。不同的水平和竖直视角,其对比度也是不同的。无论竖直视角的大小,水平视角为0°时对比度最大;当对比度大于某一数值（例如50）时,随着竖直视角从20°增加到20°,水平视角的范围先增大后减小。     

椭偏法测量表面微粗糙合金钢材料的光学常数研究

采用椭偏法测量入射光波长为0.632μm,入射角为50°～85°时合金钢的光学常数。考虑材料表面的粗糙度,用Ohlidal-Lukes理论对所测光学常数值进行了修正,发现椭偏参量的修正量随入射角增大而增大。结果表明,测量入射角在50°～70°范围内测量值与修正后计算结果基本一致,在70°～85°范围内测量值与修正后的计算结果差距较大。因此,用椭偏法测量合金钢光学常数时使入射角小于70°,测量结果会更加准确。     

点光源反射镜法向标校技术

针对基于反射式点光源进行在轨辐射定标过程中反射镜法向标校建模不够完善的问题,提出基于反射镜与相机几何模型的反射镜法向标校及矢量控制算法.通过解算模型求解相机与反射镜间的几何误差,建立了太阳图像质心坐标与反射镜法向之间的关系,可实现多点自动化标校反射镜法向,提高镜法向标校及系统指向精度.实验结果表明,利用解算后的几何模型反解不同时刻质心坐标进行多点反射镜法向标校,相机观测太阳像素角分辨率标准误差分别为:X轴方向0.02165°、Y轴方向0.01982°,综合角分辨率误差为0.02936°,优于太阳观测器对反射镜法向标校精度.实现了相机观测太阳取代人工借助太阳观测器观测太阳的自动化镜法向标校,扩展了标校灵活度,系统综合指向精度优于0.1°,为固定实验场联网自动化集中控制不同能级梯度的点光源阵列在轨辐射定标和调制传递函数检测奠定基础.     

Two-step pose estimation method based on five reference points

A two-step method for pose estimation based on five co-planar reference points is studied.In the first step, the pose of the object is estimated by a simple analytical solving process.The pixel coordinates of reference points on the image plane are extracted through image processing.Then,using affine invariants of the reference points with certain distances between each other,the coordinates of reference points in the camera coordinate system are solved.In the second step,the results obtained in the first step are used as initial values of an iterative solving process for gathering the exact solution.In such a solution,an unconstrained nonlinear optimization objective function is established through the objective functions produced by the depth estimation and the co-planarity of the five reference points to ensure the accuracy and convergence rate of the non-linear algorithm.The Levenberg-Marquardt optimization method is utilized to refine the initial values.The coordinates of the reference points in the camera coordinate system are obtained and transformed into the pose of the object.Experimental results show that the RMS of the azimuth angle reaches 0.076°in the measurement range of 0°-90°;the root mean square(RMS) of the pitch angle reaches 0.035°in the measurement range of 0°-60°:and the RMS of the roll angle reaches 0.036°in the measurement range of 0°-60°.     

Giant low-field magnetocaloric effect in EuTi(1-x)NbxO3(x = 0.05, 0.1, 0.15, and 0.2) compounds

The magnetic properties and magnetocaloric effect(MCE)of EuTi(1-x)NbxO3(x=0.05,0.1,0.15,and 0.2)compounds are investigated.Owing to electronic doping,parts of Ti ions are replaced by Nb ions,the lattice constant increases and a small number of Ti⁴⁺(3d^0)ions change into Ti³⁺(3d^1).It is the ferromagnetism state that is dominant in the derivative balance.The values of the maximum magnetic entropy change(-?SM^max)are 10.3 J/kg·K,9.6 J/kg·K,13.1 J/kg·K,and 11.9 J/kg·K for EuTi(1-x)NbxO3(x=0.05,0.1,0.15,and 0.2)compounds and the values of refrigeration capacity are 36,33,86,and 80 J/kg as magnetic field changes in a range of 0 T–1 T.The EuTi(1-x)NbxO3(x=0.05,0.1,0.15,and 0.2)compounds with giant reversible MCE are considered as a good candidate for magnetic refrigerant working at lowtemperature and low-field.     

含特异材料光子晶体隧穿模的偏振特性

构造了由普通材料A(SiO₂)和电单负材料B组成的(AB)^N(BA)^N型一维光子晶体.数值计算表明原禁带的1907.3 nm处出现了一个十分尖锐的隧穿模. 入射角增加,该隧穿模的透射率和半峰全宽度均保持不变,但位置发生蓝移, 入射角在15°-65°的区间内,移动率的绝对值 |dλ/dθ| 较大.当B介质的磁导率μ_B 从5增加到10时,只是隧穿模的位置发生了红移. 介质的几何厚度增加时,隧穿模的透射率不变,但其位置红移明显,半峰全宽略有增加.     

基于个体眼光学结构的波前眼镜设计

提出一种在个体眼光学结构基础上根据波前数据设计波前眼镜的新方法。建立了个性化的眼光学结构,并将眼球和镜片视为统一的镜一眼光学系统,用光学设计的优化方法给出镜片的结构数据,并分析了±7°视场和眼球旋转±20°时,该镜一眼系统的成像情况。与波前拟合的方法相比,该方法设计的波前眼镜离焦差为（-0．057±0．015）m^-1,像散差为（0．015±0．013）m^-1散光轴位差为（0．100±0．316）°。镜一眼系统的矫正视力均大于1．25,其中8只被试眼的视力可达1．5以上。10只被试眼在转动±20°情形下的0°视场成像相比于直视的情况均略有下降,而7°视场的成像质量相比于直视的情况下降则更为明显。由该方法给出的验光结果客观可信,可用于对佩戴波前眼镜后人眼的视觉质量的预先评估。     

低能He~(2+)与He原子碰撞转移电离出射电子能谱研究

利用反应显微成像谱仪对70和100keV He2+与He原子碰撞转移电离(TI)过程中不同出射角度的电子能谱进行了测量,观测到出射电子能谱具有如下分布特征:出射电子速度分布介于0和入射离子速度vp之间;在不同出射角度电子能谱分布均有一极大值存在,随着出射角度的增大,能谱分布极大值逐渐减小;当电子出射角度等于45°时,多数电子集中在0eV附近。上述特征可由低能离子-原子碰撞"准分子"模型进行定性解释。在100keV He2+-He转移电离出射电子能谱中有靶电子被俘获至散射离子连续态(electron capture to continuum,简称ECC)电子的贡献,这可看做是动力学两步过程的作用。     

激光测距机主要参数校准测量不确定度分析

简述激光测距机主要参数校准装置的组成，通过对其主要参数(最大测程、最小测程、测距准确度、重复频率、束散角)的校准测量进行详细的不确定度分析，评价激光测距机主要参数校准装置的达标程度。