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.     

斜程大气中聚焦J0相关部分相干光束的传输特性

采用部分相干光交叉谱密度理论,给出了适用于任意大气湍流条件的斜程湍流大气传输J₀相关部分相干光束在接收面内的长期平均光强分布、光束长期扩展和质量因子的解析表达式,分析了天顶角、传输距离、光源相干性以及湍流外尺度对接收面光强分布特性和光束扩展的影响.研究结果表明：在天顶角和传输距离一定的条件下,通过选择合适的光源相干性可控制焦面光强为平顶分布或中心光强为最大;在传输距离给定的条件下,随着天顶角或大气湍流外尺度的增加,焦斑光强分布均由中央凹陷分布逐渐变为高斯分布.焦面附近光强的中央凹陷比焦面的中央凹陷浅.J₀相关部分相干光束实际焦斑位置随天顶角、湍流外尺度的增加以及相干性减弱而移向发射端.关键词：部分相干束大气湍流0相关')\" href=\"#\">J₀相关斜程传输     

基于手征双重模型研究a0(980)介子对非对称物质的影响

在本工作中,通过基于近似U(2)_L × U(2)_R对称性构建包含a₀(980)介子的手征双重模型,研究了同位旋矢量标量介子a₀(980)（即δ）对不对称物质性质的影响,并研究了a₀(980)对对称物质性质的影响,如对称能S(n_B)、对称能不可压缩系数K_sym、对称能偏斜系数Q_sym。发现a₀(980)介子对这些核物质性质有显著影响,特别是在核子手征不变质量m₀较小的情况下。还研究了a₀(980)介子对中子星(NS)性质的影响,发现它增加了NS的半径,特别是那些具有中等质量的中子星。最后,通过与最近约束的K_sym和NS观测数据比较,进一步将L=57.7 MeV时核子的手征不变质量值限制在640 MeV<m₀<860 MeV。     

四方相BaTiO3缺陷性质的第一性原理计算

采用基于密度泛函理论的第一性原理方法,研究了BaTiO₃在四方相下的各种缺陷性质.计算结果表明,在富氧环境下,钛的中性氧空位、分肖特基缺陷2V^3-_Ti+3V²⁺_O形成能分别为最低;而当体系处在还原环境下时,氧空位逐渐成为主要缺陷,其形成能最低.由于四方相下存在较强的Ti—O键共价杂化,四方相下全肖特基缺陷V^2-_{Ba关键词：缺陷第一性原理3}')\" href=\"#\">BaTiO₃     

微观相场法模拟Ni75Al5.3V19.7 中L12和D022结构反位缺陷的演化

运用微观相场法研究Ni₇₅Al_5.3V_19.7合金沉淀过程中L1₂结构和D0₂₂结构反位缺陷发现：在沉淀初期,L1₂结构反位缺陷Al_Ni,V_Ni,Ni_Al,D0₂₂结构反位缺陷V_Ni,Al_{Ni关键词：微观相场反位缺陷L12结构')\" href=\"#\">L12结构D022结构')\" href=\"#\">D022结构}     

A comparative study of thermal properties of similar Zn-free and Zn-doped thin films

Zn-doped sprayed thin films have been grown on binary In₂S₃ substrates under the mean temperature (T_d = 320 °C). Further studies Amlouk et al. [M. Amlouk, M.A. Ben Said, N. Kamoun, S. Belgacem, N. Brunet, D. Barjon, Japan Journal of Applied Physics 38 (1999) 26-30]; Lazzez et al. [S. Lazzez, K. Boubaker, M. Amlouk, Indirect measurement of Zn-doped In₂S₃ NANO films SPECIFIC heat capacity, International Journal of Nanoscience 7 (2008) 1–5.]; Lazzez et al. [S. Lazzez, K. Boubaker, T. Ben Nasrallah, M. Mnari, R. Chtourou, M. Amlouk, S. Belgacem, Structural and optoelectronic properties of InZnS sprayed layers, Acta Physica Polonica A 114 (2008) 869–880.] investigated the band gap shift, the structural and morphological changes induced by this doping. In this study, a quantitative comparative evaluation of the thermal properties of the as-grown layers is carried out. The obtained results, parallel to further information, plea for the superior thermal efficiency of the recently proposed Zn-doped ternary compounds.     

Ultraviolet photovoltaic characteristic of MgB2 thin film

Fast photoelectric effects have been observed in MgB₂ thin filmfabricated by chemical vapour deposition. The rise time was $sim $10ns and the full width at half-maximum was sim185,ns for the photovoltaicpulse when the film was irradiated by a 308,nm laser pulse of 25,ns induration. X-ray diffraction and the scanning electron microscope revealedthat the film was polycrystalline with preferred c-axis orientation. Wepropose that nonequilibrium electron--hole pairs are excited in the grainsand grain boundary regions for MgB₂ film under ultraviolet laser andthen the built-in electric field near the grain boundaries separatescarriers, which lead to the appearance of an instant photovoltage.     

光折变法制备的As2S8条形波导的光阻断效应

实验研究了As₂S₈薄膜光折变现象.提出并采用紫外光激励的方法试制了As₂S₈条形波导,导模激励显示该波导具有良好的导波特性.在此基础上,考察了As₂S₈条波导的光阻断效应,实现了光-光效应的开关功能.关键词：光波导技术2S₈条形波导')\" href=\"#\">As₂S₈条形波导光阻断效应光激励法     

Antisite defect types and temporal evolution characteristics of D0<Subscript>22</Subscript>-Ni<Subscript>3</Subscript>V structure: Studied by the microscopic phase field

Microscopic phase field simulation is performed to study antisite defect type and temporal evolution characteristic of D0₂₂-Ni₃V structure in Ni₇₅Al _x V_25−x ternary system. The result demonstrates that two types of antisite defect V_Ni and Ni_V coexist in D0₂₂ structure; however, the amount of Ni_V is far greater than V_Ni; when precipitates transform from D0₂₂ singe phase to two phases mixture of D0₂₂ and L1₂ with enhanced Al:V ratio, the amount of V_Ni has no evident response to the secondary L1₂ phase, while Ni_V exhibits a definitely contrary variation tendency: Ni_V rises without L1₂ structure precipitating from matrix but declines with it; temporal evolution characteristic and temperature dependent antisite defect V_Ni, Ni_V are also studied in this paper: The concentrations of the both defects decline from high antistructure state to equilibrium level with elapsed time but rise with elevated temperature; the ternary alloying element aluminium atom occupies both α and β sublattices of D0₂₂ structure with a strong site preference of substituting α site. Supported by the National Natural Science Foundation of China (Grant Nos. 50671084 and 50875217), the Doctorate Foundation of Northwestern Polytechnical University of China (Grant No. CX200806), the China Postdoctoral Science Foundation Funded Project (Grant No. 20070420218), and the Natural Science Foundation of Shaanxi Province of China     

La掺杂对Bi4Ti3O12薄膜铁电性能的影响

利用Sol-Gel法在Pt/Ti/SiO₂/Si衬底上制备出Bi₄Ti₃O₁₂和Bi_3.25La_0.75Ti₃O₁₂薄膜,研究了La掺杂对Bi₄Ti₃O₁₂薄膜的晶体结构、铁电性能和疲劳特性的影响,发现La掺杂没有改变Bi₄Ti₃O₁₂薄膜的基本晶体结构,并且提高了Bi₄Ti₃O₁₂铁电薄膜的剩余极化值和抗疲劳性能,对La掺杂改善Bi₄Ti₃O₁₂铁电薄膜性能的机理进行了讨论.关键词：铁电性能4Ti₃O₁₂薄膜')\" href=\"#\">Bi₄Ti₃O₁₂薄膜3.25La_0.75Ti₃O₁₂薄膜')\" href=\"#\">Bi_3.25La_0.75Ti₃O₁₂薄膜sol-gel法La掺杂