The effect of anti-hydrogen bond on Fermi resonance: A Raman spectroscopic study of the Fermi doublet ν1—ν12 of liquid pyridine

The effects of anti-hydrogen bond on the ν₁—ν₁₂ Fermi resonance (FR) of pyridine are experimentally investigated by using Raman scattering spectroscopy. Three systems, pyridine/water, pyridine/formamide, pyridine/carbon tetrachloride, provide varying degrees of strength for the diluent-pyridine anti-hydrogen bond complex. Water forms a stronger anti-hydrogen bond with pyridine than with formamide, and in the case of adding non-polar solvent carbon tetrachloride, which is neither a hydrogen bond donor nor an acceptor and incapable of forming hydrogen bond with pyridine, the intermolecular distance of pyridine will increase and the interaction of pyridine molecules will reduce. The dilution studies are performed on the three systems. Comparing with the values of Fermi coupling coefficient W of the ring breathing mode ν ₁ and triangle mode ν ₁₂ of pyridine at different volume concentrations, which are calculated according to the Bertran equations, in three systems, we find that the solution with the strongest anti-hydrogen bond, water, shows the fastest change in the ν₁—ν₁₂ Fermi coupling coefficient W with the volume concentration varying, followed by the formamide and carbon tetrachloride solutions. These results suggest that the stronger anti-hydrogen bond-forming effect will cause a greater reduction in the strength of the ν₁—ν₁₂ FR of pyridine. According to the mechanism of the formation of anti-hydrogen bond in the complexes and the FR theory, a qualitative explanation for the anti-hydrogen bond effect in reducing the strength of the ν₁—ν₁₂ FR of pyridine is given.     

β型烧绿石氧化物超导体AOs2O6 (A=K, Rb) 的 声子软化与超导电性

运用基于密度泛函理论的第一性原理计算方法, 研究两种β 型烧绿石氧化物超导体AOs₂O₆(A=K, Rb) 的结构稳定性, 声子软化以及与超导电性的关系. 通过计算发现, AOs₂O₆中碱金属原子A(=K, Rb) 沿〈111〉 晶向具有不稳定性, 且以K原子的不稳定性更为突出. 同时, 计算得到的KOs₂O₆在布里渊区中心的声子频率普遍比RbOs₂O₆的低, 使得KOs₂O₆的电声子耦合常数比RbOs₂O₆的大. 本文计算结果表明, 较小的碱金属原子K位于较大的氧笼子中, 活动性较强, 导致声子的软化, 是引起KOs₂O₆具有较强的电声子耦合及较高的超导转变温度的根本原因. 这些结果对解释两种β 型烧绿石氧化物超导体AOs₂O₆(A=K, Rb) 的超导电性具有重要意义.     

AD95陶瓷的层裂强度及冲击压缩损伤机理研究

采用激光位移干涉测试技术测量了AD95 陶瓷在一维应变冲击压缩下的自由面或样品/窗口界面粒子速度剖面, 确定了层裂强度及其与加载应力的变化关系, 在此基础上讨论了冲击压缩损伤程度与加载应力的关系. 研究结果表明: AD95陶瓷发生冲击压缩损伤的阈值应力约为3.7 GPa, 小于其雨贡纽弹性极限(HEL, 约5.47 GPa); 小于阈值应力不发生冲击压缩损伤, 层裂强度随加载应力的增加逐渐增大; 大于阈值应力冲击压缩损伤快速发展, 层裂强度迅速降低; 在HEL附近层裂强度降低到零, 丧失了抗拉能力, 表明材料发生了严重的冲击压缩损伤.     

纳米Cu颗粒等温晶化过程的分子动力学模拟研究

采用分子动力学方法和镶嵌原子势,模拟了500个Cu原子(简称Cu₅₀₀) 组成的纳米颗粒的等温晶化过程.利用修正的均方位移、键对分析技术和内在结构(IS) 等方法对该过程中的结构和动力学行为进行分析研究.结果显示:与块体金属不同的是, Cu₅₀₀纳米颗粒在某一温度保温时,其晶化时间并不是一个定值, 而是存在一个统计分布,并且保温温度越低其晶化时间的分布范围越广, 最长晶化时间越长.在低温晶化时, Cu₅₀₀经历了一系列中间构型的转变才达到晶态, 表现出多步晶化的特征.文章作者研究了颗粒的初始构型对晶化进程的影响, 发现颗粒的初始结构特征和能量状态对其随后的晶化过程有着重要的影响, 同一温度下,颗粒初始构型的IS能量越低其晶化时间越长,这一点在低温时尤其明显.     

Optical Properties of Highly Strained GaInAs／GaAs Quantum Wells Grown by Sb Assistance

Optical properties of highly strained GaInAs/GaAs quantum wells (QWs) grown by molecular beam epitaxy with Sb assistance are investigated. The samples grown by Sb incorporation and Sb pre-deposition methods display high room-temperature photoluminescence (PL) intensity at extended 10ng wavelength. This result is explained by the surfactant effects of Sb during the growth of GaInAs/GaAs QW systems. An abnormal Sshaped temperature dependence of the PL peak position is found in the In0.42Ga0.58As/GaAs triple QWs sample grown with Sb pre-deposition. By investigating the transmission electron microscope images and time-resolved PL spectra, it is found that the S-shaped temperature dependence of the PL peak position originates from the exciton 10calization effect brought by the Sb-rich clusters on the QW interface.     

广义不可逆卡诺制冷机的生态学最优性能

以反映制冷机火用输出与熵产率之间最佳折衷的“生态学”准则为目标 ,综合考虑热阻、热漏及工质内不可逆性 ,导出了牛顿传热定律系统广义不可逆制冷机的生态学最优性能 ,由数值算例对不同损失情况下制冷机的性能变化规律进行了比较。文中结果对实际制冷机的设计工作具有一定的理论指导意义     

工业多用途工具：微波激励KW级CO2激光器

提高气体放电的功率注入密度，是进一步发展工业用高功率ＣＯ２激光器的关键．为此，我们采用自制的变形 Ｍａｇｉｃ Ｔ型微波放电腔，克服了由于高频趋肤效应引起的放电不均匀，实现了大体积的均匀的微波辉光放电．在用于激励高功率ＣＯ２激光的原理性实验中，获得大于１ｋｗ的激光输出功率，光电效率优于２５％，首次达到商用水平．     

激波管内氢-氧混合气体爆轰温度的测量

 以光纤传输光能，用多通道光学高温计，在垂直和平行于爆轰波传播方向上，测量了激波管中氢氧（或含氮）混合气体的爆轰温度。在20~53 kPa压力范围内，进行了六种初始压力氢氧混合气体的爆轰，分别测出横向温度和纵向温度；这两种温度在实验测量的误差范围内是一致的，并与正常爆轰的理论值符合得相当好。     

关于Robbins代数与Heyting代数的类似性质

Ｓ．Ｗｉｎｋｅｒ在文〔１〕中给出了Ｒｏｂｂｉｎｓ代数成为Ｂｏｏｌｅａｎ代数的一个较弱的条件。本文将讨论Ｈｅｙｔｉｎｇ代数成为Ｂｏｏｌｅａｎ代数的条件，我们发现Ｈｅｙｉｎｇ代数成为Ｂｏｏｌｅａｎ代数的条件与Ｒｏｂｂｉｎｓ代数成为Ｂｏｏｌｅａｎ代数的条件相似，从而提示了Ｈｅｙｔｉｎｇ代数与Ｒｏｂｂｉｎｓ代数之间具有一定的关系。