＝4．03GeV下τ~±→π~＋π~－π~±υ_τ衰变的测量

利用北京谱仪（ＢＥＳ）在４．０３ＧｅＶ正负电子对撞能量下获取的数据，［研究了，τ＋τ－产生过程．借助双标记方法分析了τ±→π＋π－π±υτ衰变事例．测定分支比Ｂｒ（τ±→ａ１±υτ→ρ０π±υτ，ρ０→π＋π－＝（７．３±０．５）％，Ｂｒ（τ±→Ｋ＊±υτ→Ｋｓ０π±υτ，Ｋｓ０→π＋π－）＝（０．６±１．５）×１０－３．并由Ｄａｌｉｚ投影分布的分析，确认ａ１的主要衰变方式ρπ．同时，也观察到ａ１衰变中以Ｓ波贡献为主的现象．采用Ｋｕｈｎ模型拟合实验数据，得到：ｍａ１＝１．２４±０．０２ＧｅＶ，Γａ１Ｔ＝０．５７±０．０７ＧｅＶ．     

ICP—AES法同时测定掺质钒酸钙晶体中的钙,钒,钕,镱,锗

本文采用ＩＣＰ－ＡＥＳ法同时测定了掺质Ｃａ３（ＶＯ４）２，晶体中Ｃａ，Ｖ，Ｎｄ，Ｙｂ，Ｇｅ的含量，选择了合适的分析谱线和积分时间，试样用硝酸溶解后直接测定，方法简便，准确，快速，合成试样中各被测元素的回收率为９８％－１０４％，相对标准偏差〈４．０％，Ｎｄ，Ｙｂ，Ｇｅ的检出限为０．０００２－０．０１８μｇ／ｍＬ。     

Gd＿（1－x）Ca＿xBa＿2Cu＿3O＿（7－y）高温超导体压力效应的研究

研究了Ｇｄ＿（１－ｘ）Ｃａ＿ｘＢａ＿２Ｃｕ＿３Ｏ＿（７－ｙ）（０．０≤Ｘ≤０．２０）高温超导体在常压和高压下的超导电性在１－３００Ｋ温度范围内，利用Ｂｒｉｄｇｍａｎ对顶砧获得压力达９．０ＧＰａ，测量了（Ｘ＝０．１０，０．１５，０．２０）样品的ｄＴ＿ｃ／ｄｐ分别为７．６８，７．８和４．４６Ｋ／ＧＰａ。发现Ｔ＿ｃ的压力导数随着ｃａ￣（２＋）含量的增加而下降，分析了氧含量对Ｔ＿ｃ和ｄＴ＿ｃ／ｄＰ的影响．利用常压下晶格参数精修值和阳离子与氧离子间距随压力的改变，说明ＣｕＯ＿２面在超导电性上的作用，用ＣｕＯ＿２面之间耦合解释Ｔ＿ｃ（Ｐ）曲线的非线性关系。     

波长色散X射线荧光光谱法测定黄金饰品含金量

本文提出应用波长色散Ｘ射线荧光光谱仪测定黄金饰品含金量的方法，本法对原有样品盒进行了改造，增设特制窗口和采取样品固定等措施，以系列参考标样建立校准曲线，用经验系数法校正基体效应。比例模拟法校正含量。９个参考标样和１６个金标牌的测定结果表明，在含金量为３７．５０％－９９．９９％的范围内，方法的准确度好：含金量在９９．９９％－９８．９８％范围时，误差为０．０３％－０．１２％，在９８．９８％－３７．５０％范围时，误差为０．０１％－０．５２％，选用含金量不同的５个参考标样为代表，以０．７和１．４的模拟比例，经不同时间多次测定进行统计，相对标准偏差为０．０５％－０．５０％，说明方法的精密度好，本法操作方便，时样品无破坏     

ICP-AES法同时测定氯化锂和氢氧化锂中七种杂质元素

本文报导了用ＩＣＰ－ＡＥＳ法同时测定ＬｉＣｌ和ＬｉＯＨ·Ｈ２Ｏ中７种杂质元素Ａｌ、Ｂａ、Ｃａ、Ｆｅ、Ｍｇ、Ｓｉ、Ｚｎ的分析方法。研究了基体元素锂对被测元素的基体效应，采用基体匹配法与背景扣除法进行校正。被测元素的检出限为０．１－９．４ｎｇ／ｍＬ，加标试验回收率为９２％－１０９％，当杂质元素含量为０．０００１％－０．０２８％时，相对标准偏差小于７％。方法简便、快速、准确，用于样品分析，取得了满意的结果。     

原子发射光谱法测定Fe-Ba-S三元合金中痕量Ba

在借鉴矿石中Ｂａ的测定方法基础上,采用交流电弧粉末法,对试样的处理,基体的配制,内标及缓冲剂的选择等进行了实验,拟定了三元合金中痕量Ｂａ的原子光谱测定方法。在所选择的最佳实验条件下,对７９个试样进行分析测定,回收率在８３．０％－１１７．３％,检出限为６５ｐｐｂ;对含０．００１９ｍｇＢａ／ｍＬ的标准样品进行重复测定,相对标准偏差为±１５．３％,完全可满足０．１２－１２０ｐｐｍ范围内痕量Ｂａ的测定。     

Ga1—xAlxAs外延片有源区Al组份的测定方法

由于ＧａＡｓ与ＡｌＡｓ晶格常数相近，ＧａＡｓ晶格常数为０．５６５３５ｎｍ，ＡｌＡｓ的晶格常数为０．５６６０５ｎｍ，当固熔体中Ａｌ组份ｘ值从０变到１时，晶格常数变化约为０．１５％．因此，在ＧａＡｓ衬底上生长Ｇａ１－ｘＡｌｘＡｓ时，在界面处的失配位错少，...     

正三辛胺萃取－5－Br－PADAP－OP显色体系光度法测定铜

采用５－Ｂｒ－ＰＡＤＡＰ－ＯＰ显色体系测定铜，考查了测定条件。以正三辛胺萃取分离干扰高子，考查了萃取分离条中。人工合成样品回收率１００．８％，铝合金标样测定误差＜－２．２％，人发分析结果的相对标准偏差＜４．０％。     

ICP－AES法测定栽培灵芝中9种微量元素

本文报导了采用美国ＬｅｅｍａｎＬａｂｓ公司生产的ＰＳ－Ⅰ型中阶梯光栅光谱仪，对栽培灵芝中Ｇｅ、Ｃａ、Ｍｇ、Ｚｎ、Ｃｕ、Ｍｎ、Ｆｅ、Ｋ、Ｎａ等元素进行了测定。为防止Ｇｅ的挥发损失，采用了ＨＮＯ３－ＨＣｌＯ４低温湿法消化的前处理方法。相对标准偏差为１．３１％－９．１１％，回收率为９１．０％－１１０．０％，结果令人满意。     

激光蒸发进样ICP－AES测定地质祥品中的钡和锶

本文讨论了用连续ＣＯ＿２激光器蒸发地质粉末样品，ＩＣＰ－ＡＥＳ测定Ｂａ和Ｓｒ。在样品中加入适量的粘合剂和石墨粉混匀压饼，用激光全部蒸发。在蒸发室出口处加入了一只多层多孔过滤器，一定程度上改善了系统长时间工作的稳定性。对影响激光采样和ＩＣＰ－ＡＥＳ分析性能的参数进行了研究。实验结果表明，连续激光蒸发地质粉末样品、ＩＣＰ－ＡＥＳ测定Ｂａ、Ｓｒ，大部分分析结果满意。在选择的系统条件下，Ｂａ、Ｓｒ的检出限分别为２．６μｇ·ｇ￣－１和３．０μｇ·ｇ￣－１；精密度ＲＳＤ分别为６．３％（４７０μｇ·ｇ￣－１）和５．６％（５２μｇ·ｇ￣－１）     

Influence of the grain boundary barrier height on the electrical properties of Gallium doped ZnO thin films

The pulsed laser deposition (PLD) technique is used to deposit Gallium doped zinc oxide (GZO) thin films on glass substrates at 250 with different Gallium (Ga) doping concentration of 0, 1.0, 3.0 and 5.0%. The influence of Ga doping concentration on structure, chemical atomic compositions, electrical and optical properties was investigated by XRD, XPS, Hall measurement and UV spectrophotometer, respectively. The relationship between electrical properties and Ga doping concentration was clarified by analyzing the chemical element compositions and the chemical states on the GZO films. It is found that the carrier concentrations and oxygen vacancies in the GZO films increase with increasing Ga doping concentration. The lowest resistivity (3.63 × 10⁻⁴ Ω cm) and barrier height of grain boundaries (14 mV) were obtained with 3% Ga doping. In particular, we suppose the band gap of 5% Ga doping sample larger than that of 3% Ga doping sample is due to the quantum size effect from the amorphous structure rather than Moss-Burstein shift.     

Monte Carlo simulation for temperature dependence of Ga diffusion length on GaAs(0 0 1)

Diffusion length of Ga on the GaAs(0 0 1)-(2×4)β2 is investigated by a newly developed Monte Carlo-based computational method. The new computational method incorporates chemical potential of Ga in the vapor phase and Ga migration potential on the reconstructed surface obtained by ab initio calculations; therefore we can investigate the adsorption, diffusion and desorption kinetics of adsorbate atoms on the surface. The calculated results imply that Ga diffusion length before desorption decreases exponentially with temperature because Ga surface lifetime decreases exponentially. Furthermore, Ga diffusion length L along and [1 1 0] on the GaAs(0 0 1)-(2×4)β2 are estimated to be and L_[110]200 nm, respectively, at the incorporation–desorption transition temperature (T860 K).     

Structural and photoluminescence properties of SnO2:Ga films deposited on α-Al2O3 (0 0 0 1) by MOCVD

Gallium-doped tin oxide (SnO₂:Ga) films have been prepared on α-Al₂O₃ (0 0 0 1) substrates at 500 °C by the pulse mode metalorganic chemical vapor deposition (MOCVD) method. The relative amount of Ga (Ga/(Ga+Sn) atomic ratio) varied from 3% to 15%. Post-deposition annealing of the films was carried out at different temperatures for 1.5 h in ambient atmosphere . The structural, electrical, optical and photoluminescence (PL) properties of the films have been investigated as a function of annealing temperature. All the films have the rutile structure of pure SnO₂ with a strong (2 0 0) preferred orientation. A single ultraviolet (UV) PL peak near 337.83 nm was observed at room temperature for the 3% Ga-doped as-grown film and near 336 nm for the 15%-doped film, which can be ascribed to electron transition from the oxygen vacancy and interstitial Ga³⁺ donor levels to the acceptor level formed by the substitution of Ga³⁺ for the Sn site. After annealing, the luminescence spectra have changed a little bit, which is being discussed in detail.     

In situ investigation of the formation of Cu(In,Ga)Se2 from selenised metallic precursors by X-ray diffraction—The impact of Gallium, Sodium and Selenium excess

The chemical reactions during rapid thermal processing of stacked elemental layers were investigated by angle-dispersive in situ X-ray diffraction. With a time resolution of 5 diffractograms per minute four different solid state reactions resulting in ternary chalcopyrites were identified: (A) CuSe+InSe→CuInSe₂, (B) Cu₂Se+2InSe+Se→2CuInSe₂, (C) Cu₂Se+In2Se₃→2CuInSe₂, (D) Cu₂Se+Ga2Se₃→2CuGaSe₂. All these reactions form pure tenary chalcopyrites. The reaction resulting in the mixed crystal Cu(In,Ga)Se₂ starts not before (B) has begun. The reaction speed of (A) and the fraction of CuInSe₂ formed by (B) depend on Na-doping and Se-pressure, (C) takes place only, if the reaction paths (A) and (B) are suppressed. Reaction (D) is observed only, if 25% In is replaced by Ga in the precursor. The diffractograms were evaluated by Rietveld refinement to give the phase contents of the samples as a function of reaction time.     

Ga掺入对立方相MgZnO薄膜晶体结构的影响

采用金属有机物化学气相沉积方法生长了立方相Mg_0.56Zn_0.44O：Ga薄膜,Ga在MgZnO中的摩尔分数为2.8%~4.5%。低掺杂水平的MgZnO可以保持其良好的结晶特性。随着Ga元素的摩尔分数升高至3.1%、3.3%与4.5%,立方相MgZnO中分别出现了Ga₂O₃、ZnO与ZnGa₂O₄分相。其中,Ga₂O₃与ZnGa₂O₄相的出现是由于Ga的掺杂使这两相在MgZnO基质中饱和析出,而ZnO分相被归因于Ga的引入部分破坏了立方MgZnO的亚稳态结构状态,使组分原本就处于分相区的立方MgZnO出现相分离。     

TiO2分子在GaN(0001)表面吸附的理论研究

采用基于密度泛函理论的平面波超软赝势法,计算了TiO₂分子在GaN(0001)表面的吸附成键过程、吸附能量和吸附位置. 计算结果表明不同初始位置的TiO₂分子吸附后,Ti在fcc或hcp位置,两个O原子分别与表面两个Ga原子成键,Ga-O化学键表现出共价键特征,化学结合能达到7.932-7.943eV,O-O连线与GaN[1120]方向平行,与实验观测(100)[001] TiO₂//(0001)[1120]GaN一致. 通过动力学过程计算分析,TiO₂分子吸附过程经历了物理吸附、化学吸附与稳定态形成的过程,稳定吸附结构和优化结果一致. 关键词： GaN(0001)表面 2分子')" href="#">TiO₂分子 密度泛函理论 吸附     

光电直读光谱法测定稀土铝合金中La,Ce,Pr,Nd,Sm ,Si,Fe,Cu

本文报道了稀土铝合金中La,Ce,Pr,Nd,Sm,Si,Fe,Cu的光电直读光谱测定，对光源的激发方式及最佳工作条件进行了选择，应用KH－5高能预火花光源，采用单向全功率放电，先冲洗3秒，然后预燃5秒，曝光10秒。各元素谱线间无干扰，。使用固体试样，样品处理简单。经试验验证该法简便快速，精密度准确度高，含量在0．001％－0．002％之间RSD＜6％，0．02％－0．3％之间RSD＜3％，标准样品的测定值与准确值吻合较好，结果令人满意。     

Extended X-ray absorption fine structure (EXAFS) and X-ray absorption near-edge structure (XANES) study of melt-spun Fe85Ga15 ribbons

The local structure in melt-spun Fe₈₅Ga₁₅ ribbons with a width ∼3 mm and thickness ∼60 μm produced in argon atmosphere was studied by analyzing EXAFS and XANES data. The following results were obtained: Ga–Ga bonds were not detected excluding the tendency to form clusters of Ga atoms; Ga substitutes Fe creating a local strain of about +1% on the first shell Fe–Ga bond, whereas on the second Fe–Ga shell strain quickly relaxes down to +0.3%; XANES spectra are compatible with a random substitution of Fe atoms by Ga atoms in the A2 structure. From the AFM investigation, we observed that at the surface (free side) of the ribbon the particles are elongated along the ribbon (∼2 μm×∼5 μm) and each particle is formed by small grains of average size of 200 nm.     

Electronic structure of HgGa2S4

The electronic structure and chemical bonding in HgGa₂S₄ crystals grown by vapor transport method are investigated with X-ray photoemission spectroscopy. The valence band of HgGa₂S₄ is found to be formed by splitted S 3p and Hg 6s states at binding energies BE=3-7 eV and the components at BE=7-11 eV generated by the hybridization of S 3s and Ga 4s states with a strong contribution from the Hg 5d states. At higher binding energies the emission lines related to the Hg 4f, Ga 3p, S 2p, S 2s, Hg 4d, Ga LMM, Ga 3p and S LMM states are analyzed in the photoemission spectrum. The measured core level binding energies are compared with those of HgS, GaS, AgGaS₂ and SrGa₂S₄ compounds. The valence band spectrum proves to be independent on the technological conditions of crystal growth. In contrast to the valence band spectrum, the distribution of electron states in the bandgap of HgGa₂S₄ crystals is found to be strongly dependent upon the technological conditions of crystal growth as demonstrated by the photoluminescence analysis.     

二维缺陷GaAs电子结构和光学性质第一性原理研究

采用基于密度泛函理论的第一性原理方法计算了存在Ga空位缺陷和掺杂B原子的二维GaAs的能带结构、态密度和光学性质.计算结果表明空位缺陷二维GaAs显示出金属特性,B原子的引入使体系变为间接带隙半导体,禁带宽度为0.35 eV.态密度计算发现体系低能带主要由Ga的s态、p态、d态和As的s态、p态构成;高能带主要由Ga和As的s态、p态构成.掺杂B原子与存在空位缺陷的二维GaAs相比,静态介电常数相对较低,变为8.42,且易于吸收紫外光,在3.90～8.63 eV能量范围具有金属反射特性,反射率达到52%.