倾转晶体电子衍射图的自动标定

用电子计算机标定倾转晶体电子衍射斑点指数的计算公式如下:[hkl]=[xy0]Γ^(θ)Γ^(ω₀-ω)Γ^(θ₀)P^-1H,其中θ,ω为倾转角,θ₀,ω₀为初始倾转角。一个适合于任意晶系的计算机程序已经编写出来。与极图法比较起来,用计算机标定既简便又迅速。 关键词：     

氨分子在000和201带的选择光离解

本文利用脉冲紫外激光(UV)选择激发氨分子到?¹A″₂电子激发态的两个最低振动能级ν′₂=0和ν′₂=1(ν₂振动),然后检测新生态H原子的飞行谱(TOF),研究了氨分子的光碎片动力学。光谱证实了最近所测的离解能D₀⁰(H-NH₂)=4.645eV;绝大多数生成的NH₂(X²B₁)基处于非振动激发,但是具有围绕a惯性轴的高度转动激发。通过NH₃(?)的ν′₂=1光离解产生的NH₂(X)基具有较高的内部激发,并且显示了在N=K_a转动能级上的反转布居。 关键词：     

动态法拉第效应及其损耗机制

在磁光介质中，法拉第磁光效应的动态特性与静态特性具有明显的差别．交变法拉第旋转θ_t的实部θ′_t恒小于静态法拉第旋转θ_ｓ的实部θ′_ｓ，θ′_t＜θ′_ｓ，而虚部θ″_t＞θ″_ｓ．分析(BiTm)₃(FeGa)₅O₁₂磁光单晶薄膜法拉第效应的测量结果表明，在交流磁场频率ω＞10 关键词：     

超冷铯(60D5/2)2 Rydberg分子的双色光缔合光谱

本文主要从理论和实验上研究超冷铯（60D_5/2）₂ Rydberg分子的双色光缔合光谱.数值计算了铯60D_5/2 Rydberg原子对态的长程电多极相互作用和（60D_5/2）₂ Rydberg分子的绝热势能曲线,获得了（60D_5/2）₂ Rydberg分子的势阱深度和平衡间距.实验上利用双色光缔合超冷铯原子的方法制备了（60D_5/2）₂ Rydberg分子.其中,第一色激光（pulse-A）双光子共振激发种子Rydberg原子A;第二色激光（pulse-B,失谐于分子的束缚能）共振激发第二个Rydberg原子B,原子A与B由分子势阱束缚形成超冷（60D_5/2）₂ Rydberg分子.由脉冲场电离探测技术获得Rydberg分子的光缔合光谱,测量的Rydberg分子的势阱深度与理论计算结果相一致.     

无格点基底表面的杂质分布对分枝状凝聚体的影响

根据含杂质熔融玻璃表面金原子凝聚的实验规律，在原子团簇具有随机的线扩散步长和刚性转动角的特征条件下，建立了含杂质无格点基底表面上改进的杂质限制团簇-团簇(IRCCA)凝聚模型.对团簇的扩散、刚性转动以及凝聚全过程进行了计算机模拟，系统地研究了杂质区域分布情况对分枝状凝聚体诸多特性的影响.结果表明规则分布的杂质对凝聚体生长的影响比随机分布的杂质大，导致杂质规则分布的基底表面上的分枝状凝聚体的数密度更大，分枝状凝聚体的回旋半径，凝聚体平均大小及分形维数更小. 关键词： 薄膜生长 Monte Carlo模拟 分形 杂质     

铝-铜-镓三元系合金相图

铝-铜-镓三元系合金相图的室温截面已经用X射线方法测定出来了。室温固相截面包含11个单相(即α, γ₂, γ′, δ, ζ₁, ζ₂, η₂, θ, θ′,α_铝和镓)相区,14个双相(即α + ζ₁, α+ γ₂, α + γ′, γ₂ + γ′, γ′+ ζ₁, γ₂+δ, γ′+δ,δ +ζ₂, ζ₂+η₂, η₂+θ,η₂+ θ′, γ′ + θ′, θ′+ 镓和θ+α_铝)相区和9个三相(即α + γ′+ζ₁, α+ γ₂+ γ′, γ₂+ γ′ + δ,γ′ + δ + θ′, δ+ζ₂+θ′, ζ₂ + η₂ + θ′, η₂+ θ′ + 镓, η₂ +θ + 镓和θ +镓+ α_铝)相区。所有单相和三个二元系内室温存在的单相相同,没有新相出现。 关键词：     

C2H221分子转动角动量定向分布(Orientation)及其碰撞弛豫和转移

利用圆偏振激光受激Raman抽运,以 C₂H₂分子为样品选择性地制备了它的电子基态单一转动态(X¹Σ⁺_g,ν″₂＝1,J″的角动量定向布居(orientation)．并从圆偏振紫外激光诱导的A¹A_u(ν′₃＝1)←X¹Σ⁺_g(ν″₂＝1)的荧光（谱）,直接测定了 C₂H₂(X¹Σ^＋_g,ν″₂＝1,J″＝4,7,8,…,13）的角动量定向布居值．从时间分辨的荧光信号谱测定了角动量定向布居的碰撞弛豫速率常数,同时还研究了由各初始激励的转动态向其他邻近转动态碰撞诱导的角动量定向布居转移． 关键词：     

CH2Br2的同步辐射光电离研究:10—12eV范围内CH2Br2的振动自电离态

报道在超声射流冷却条件下用同步辐射ＶＵＶ光源研究ＣＨ₂Ｂｒ₂的振动自电离结构．根据测量的１０５—１２３ｎｍ范围内母体离子（ＣＨ₂Ｂｒ₂⁺）的光电离产率曲线，获得ＣＨ₂Ｂｒ₂的绝热电离势为１０.２３±０.０１ｅＶ．ＣＨ₂Ｂｒ₂⁺的最低三个电子激发态，即Ａ（²Ａ₂），Ｂ（²Ｂ₁），Ｃ（²Ａ₁）分别位于１０.７８±０.０１ｅＶ，１１.２０±０.０１ｅＶ和１１.２７±０.０１ｅＶ．在１１５.０１—１２１.１５ｎｍ范围内，观察到ＣＨ₂Ｂｒ₂自电离峰叠加在若干台阶结构上，台阶平均宽度为７１６.８±４０.０ｃｍ^-1，对应于ＣＨ₂Ｂｒ₂⁺（Ｘ²Ｂ₂）中Ｂｒ-Ｃ-Ｂｒ反对称的伸缩振动（ｖ₉），所有的峰均归属为收敛于ＣＨ₂Ｂｒ₂⁺（Ｘ²Ｂ₂，ｖ⁺）振动能级的ｎｓ，ｎｐ和ｎｄ自电离Ｒｙｄｂｅｒｇ态．此外，对ＣＨ₂Ｂｒ₂光解离电离产生离子型自由基ＣＨ₂Ｂｒ⁺（Ｘ）的光电离产率曲线的结构也进行了归属 关键词：     

Li2O-2B2O3熔体的物性研究

系统测量了四硼酸锂(Li₂Ｏ-２Ｂ_２Ｏ_３)熔体的密度ρ、表面张力γ随着温度的变化规律，实验结果表明在1100K到1500K范围内Li₂Ｏ-２Ｂ_２Ｏ_３高温熔体的密度和表面张力随着温度的升高均线性减小.通过实验数据拟合得出熔体密度与温度关系为ρ(T)=2.574—4.89×１０^－４T，熔点处Li₂Ｏ-２Ｂ_２Ｏ关键词： 功能晶体 四硼酸锂 密度 表面张力     

钠米Al2O3块体材料在可见光范围的荧光现象

对不同温度退火未掺Ｃｒ的纳米结构Ａｌ₂Ｏ₃块体的荧光谱进行了系统的研究。结果表明，在纳米级勃母石，η－Ａｌ₂Ｏ₃和γ－Ａｌ₂Ｏ₃试样中均观察到两个宽的荧光带（ｐ₁和ｐ₂带），它们的波数范围分别为２００００—１４５００和１４５００—１１５００ｃｍ^－１。ｐ₁带可归结为纳米Ａｌ_{2关键词：}     

Off lattice simulations of cluster-cluster aggregation in dimensions 2–6

Cluster-cluster aggregation has been simulated in dimensions two to six using both linear and brownian cluster trajectories. Relatively efficient off lattice algorithms have allowed large clusters to be generated and values for the fractal dimensionalities of the aggregates have been obtained without finite concentration effects. The values for the fractal dimensionality are in good aggreement with lattice model simulations for euclidean dimensionalities 2–4. The effective dimensionality (D_β) obtained from the dependence of the radius of gyration on cluster size increases with increasing cluster size for all of our models (particularly for d ≥ 4). For clusters in the accessible size range (up to 10³-10⁴) D_β is slightly larger for cluster-cluster aggregation via linear trajectories than for brownian trajectories. For cluster-cluster aggregation via brownian trajectories, the limiting (large cluster size) fractal dimensionality is estimated to be 1.46 ± 0.04 for d=2,1.82 ± 0.10 for d = 3, 2.10 ± 0.15 for d = 4, 2.35 ± 0.15 for d = 4, 2.65 ± 0.25 for d = 6. For cluster- cluster aggregation via linear trajectories, the limiting fractal dimensionality is estimated to be 1.55 ± 0.04 for d = 2, 1.91 ± 0.10 for d = 3≥ 2.5 ± 0.06 for d = 5 and ≥2.64 ± 0.05 for d = 6.     

Configuration Mixing of Quark States in Baryons

Mixing angles are used to describe the SU(6) ? O(3) symmetry breaking in [70, 1^?] multiplet in the sector of the lowest mass nucleon resonances, which are investigated extensively in constituent quark models for baryon spectroscopy. The transition amplitudes for the meson photoproduction off nucleon can also be expressed in terms of the mixing angles to take into account the configuration mixing. Those amplitudes are derived as a function of the mixing angles between ${|N^2P_M{J}^-\rangle}$ and ${|N^4P_M{J}^-\rangle}$ states, with J = 1/2 and 3/2, for the processes γp → ηp, K ⁺ Λ, K ⁺ Σ ^°, K ^° Σ ⁺. The present status of our knowledge on the mixing angles between S ₁₁(1535) and S ₁₁(1650) (θ _S ), as well as between D ₁₃(1520) and D ₁₃(1700) (θ _D ) is reported. Since these resonances play very important role in the threshold region for both η and kaon production mechanisms, they are expected to provide crucial tests of different quark models for the baryon spectroscopy.     

Employing low-power reactors in studying the mixing parameter sin<Superscript>2</Superscript>(2<Emphasis Type="Italic">θ</Emphasis><Subscript>13</Subscript>)

Measurement of the mixing parameter sin²(2θ₁₃) is one of the pressing problems in neutrino physics. Projects of reactor experiments characterized by a sensitivity of sin²(2θ₁₃)≈0.01 are being presently discussed. Almost all of them are based on the one reactor-two detectors scheme. Within this methodological approach, one employs an NPP reactor of power about a few GW for an antineutrino source and two detectors of identical configurations that are arranged at different distances from the reactor. In such experiments, the systematic error may be about 1%, which ensures a precision of about 0.01. In the present study, it is proposed to use, in a measurement of sin²(2θ₁₃), the existing SuperKamiokande (SK) detector combined with its own antineutrino source, a nuclear reactor of low thermal power, about 300 MW (low-power reactor, or LPR). Such an experiment can be performed within a rather short time. An analysis that studied various detection mechanisms revealed that the LPR-SK combination would make it possible to attain a sensitivity of sin²(2θ₁₃)≈0.002.     

Classification of <Emphasis Type="Italic">T</Emphasis>-odd asymmetries for prescission and evaporated light particles in ternary and quaternary nuclear fission induced by cold polarized neutrons

A unified mechanism of the emergence of T-odd ROT- and TRI-asymmetries is proposed for describing experimental T-odd asymmetry coefficients D(θ) in the angular distributions of prescission alphaparticles that are emitted in true ternary and quaternary nuclear fission reactions induced by cold polarized neutrons. The mechanism is related to the different ways in which the Coriolis interaction of the total spin of a polarized compound fissile nucleus with the orbital moment of alpha-particles affects even (for ROT-asymmetries) and odd (for TRI-asymmetries) components of the amplitude of an undisturbed angular distribution of emitted alpha-particles. Coefficients D_ROT(θ) and D_TRI(θ) derived with this mechanism for T-odd ROT- and TRI-asymmetries successfully describe the dependences of corresponding experimental coefficients for ²³⁵U and ²³⁹Pu nuclei over the range of angles θ, and for the ²³³U nucleus in the angular range of 60° < θ < 110°. It is explained why only ROT-type T-odd asymmetries emerge for evaporated neutrons and γ-quanta emitted by fission fragments in similar reactions if we allows for the Coriolis interaction of the total spin of the compound fissile nucleus with the orbital moments of the fission fragments and the wriggling vibrations of the above nucleus near its scission point.     

Specific heat of YBa2Cu3O7−x from 4.2 to 60 K

The specific heat of superconducting oxide compound, YBa₂Cu₃O_{7 ?x} , is studied using a quasi-adiabatic calorimeter from 4.2 to 60 K. The analysis of the specific heat data below 15 K gives a value of 17 mJ/mole K² for the electronic heat capacity coefficient. The value ofθ _D(0) is determined to be 397±8 K. The variation ofθ _D with temperature was calculated in the temperature range 4.2 to 60 K.     

Effects of Monomer Size Distribution on the fractal dimensionality of diffusion-limited aggregates

Computer simulations of diffusion-limited aggregation (DLA) for monomers to investigate the effects of size and of lognormal distribution on the fractal dimensionality of the aggregates were conducted on a two-dimensional lattice. The results show the DLA clusters posses multifractal characteristics. For clusters consisting of monodisperse monomers, the bifurcation point on the graph of the pair correlation function (PCF) for each cluster is located right at the monomers size under investigation The textural dimension (D_f1) has a stable value of about 1.65, whereas the structural dimension (D_f2) decreased with increase in monomer size. For the cases with monomers in log-normal distributions, the textural dimension is around 1.67; however, the structural dimension decreases with increasing polydispersity of monomer size.     

火灾烟颗粒分形模型和球形模型光散射的比较研究

对烟颗粒的光散射进行模拟计算是研究火灾烟颗粒光散射特性的重要手段,目前对于火灾烟颗粒光散射的数值计算多采用球形或椭球模型.实际上,火灾烟颗粒的形貌与球形和椭球均存在着显著差异.扫描电子显微镜图像表明,烟颗粒具有近似分形的结构.本文利用离散偶极近似方法计算了随机取向的火灾烟颗粒分形凝团以及同体积的球形颗粒的光散射Muller矩阵,并对两者的归一化Muller矩阵元素随散射角的分布进行了比较.研究表明:火灾烟颗粒分形模型和球形模型的归一化矩阵元素F₁₁(θ)/     

Particle aggregation versus cluster aggregation in high dimensions

We distinguish two different types of irreversible aggregation-accretion of individual particles and successive aggregation of clusters of comparable size. In aggregation of particles which follow trajectories of fractal dimensionD ₁, we show that physical limits on the aggregation rate impose a lower bound on the fractal dimensionD ₀ of the aggregate. Ind-dimensional space,D ₀{d–D}₁ + 1. Thus aggregation of ballistic particles, withD ₁ = 1, is not fractal. By contrast, cluster aggregates appear to attain a finite, limitingD ₀ in high dimensions. We present a soluble model with this property, and argue that it should agree with Sutherland's binary aggregation model in high dimensions. For this model,D ₀ depends continuously on a parameter; the exponent is not universal.     

态|Ψ(3)>q中广义电场分量的偶数次N次方Y压缩

构造了由多模复共轭虚相干态、多模复共轭虚相干态的相反态和多模复共轭相干态的线性叠加所组成的一种新型的三态叠加多模叠加态光场|Ψ⁽³⁾>_q.利用多模压缩态理论,研究了态|Ψ⁽³⁾>_q中广义电场分量的偶数次等幂次N次方Y压缩特性.结果发现:态|Ψ⁽³⁾>_q是一种典型的三态叠加多模非经典光场;当压缩次数N等于2P且P为2m’+1(m’=0,1,2,…,…)时,如果各模的初始相位φ_j(j=1,2,3,…,…,q)、态间的初始相位差(θ₁-θ₂)、(θ₁-θ₃)和(θ₂-θ₃),以及各单模相干态光场的总的平均光子数等分别满足各自的取值条件,则在这种情况下态|Ψ⁽³⁾>_q的广义电场分量可呈现出偶数次的广义非线性等幂次2(2m’+1)次方Y压缩效应.     

Map dependence of the fractal dimension deduced from iterations of circle maps

Every orientation preserving circle mapg with inflection points, including the maps proposed to describe the transition to chaos in phase-locking systems, gives occasion for a canonical fractal dimensionD, namely that of the associated set of for whichf =+g has irrational rotation number. We discuss how this dimension depends on the orderr of the inflection points. In particular, in the smooth case we find numerically thatD(r)=D(r ^–1)=r ^–1/8.