一种直接测量W-J参数的实验方法

本文探索了一种直接测量W-J参数的方法. 实验选用NaCl作为试样, 在快速压缩过程中原位测量样品的温度和压力的变化值. 通过温度修正使测量值在原理上更符合等熵压缩过程的结果, 并采用大幅度增压结合中值定理得出中点压力处温度随压力的变化率, 进而根据R=(P/T) (∂T/∂P)_S关系式求出W-J参数, 整个过程没有引入其他参数. 此外, 作为对比, 我们还从相关的物态方程、经验公式和已知参数出发计算了NaCl的W-J参数及其随压力变化的关系. 结果表明: 实验测得的NaCl的W-J参数随压力增加而增加; 实验结果与计算值符合得很好. 这说明快速增压直接测量物质的W-J参数是一种可行且可靠的方法. 关键词： NaCl W-J参数 快速增压 高压     

Atomic structure and collision dynamics with highly charged ions

The research progresses on the investigations of atomic structure and collision dynamics with highly charged ions based on the heavy ion storage rings and electron ion beam traps in recent 20 years are reviewed. The structure part covers test of quantum electrodynamics and electron correlation in strong Coulomb field studied through dielectronic recombination spectroscopy and VUV/x-ray spectroscopy. The collision dynamics part includes charge exchange dynamics in ion-atom collisions mainly in Bohr velocity region, ion-induced fragmentation mechanisms of molecules, hydrogen-bound and van de Waals bound clusters, interference, and phase information observed in ion-atom/molecule collisions. With this achievements, two aspects of theoretical studies related to low energy and relativistic energy collisions are presented. The applications of data relevant to key atomic processes like dielectronic recombination and charge exchanges involving highly charged ions are discussed. At the end of this review, some future prospects of research related to highly charged ions are proposed.     

Host dependent thermal stability and frequency upconversion of Er^3＋-doped heavy metal oxyfluoride germanate glasses

The upconversion properties of Er^3＋-doped heavy metal oxyfluoride germanate glasses under 975 nm excitation have been investigated. The intense green （551 and 529 nm） and relatively weak red （657 nm） emissions corresponding to the transitions ^4S3/2→^4I15/2, ^2H11/2→^4 I15/2 and ^4F9/2 →^4I15/2, respectively, were simultaneously observed at room temperature. The content of PbF2 has an important influence on the upconversion luminescence emission. With increasing content of PbF2, the intensities of green （529 nm） and red （657 nm） emissions increase slightly, while the green emission （551 nm） increases markedly. These results suggest that PbF2 has an influence on the green （551 nm） emission more than on the green （529 nm） and red （657 nm） emissions.     

Effect of Cu doping on the magnetic and electrical properties of n=2 Ruddlesden-Popper manganates

A series of polycrystalline Cu-doped n=2 Ruddlesden-Popper manganates La1.2Sr1.8CuzMn（2-x）O7 （x=0, 0.04, 0.13） were synthesized by the solid state reaction method. The effect of Cu doping on the magnetic and transport properties has been studied. It is found that Cu substitution for Mn greatly affects the magnetic and electrical properties of the parent phase La1.2Sr1.8Mn2O7. With the increase of Cu content, the system undergoes a transition from longrange ferromagnetic order to the spin glass state and further to an antiferromagnetic order. A little of Cu dopant can lead to the samples showing semiconductor or insulator behaviour in the whole observed temperature range while the parent phase has a metal-insulator transition. These samples show colossal magnetoresistance at low temperatures and the value of it decreases with increasing Cu content.     

钙钛矿型催化活性材料结构与性能的研究——Ⅲ.(La_(1-x)□_x)(Co_(1-y)□_y)O_(3-δ)体系

应用多晶X射线衍射法及Pauling键价理论,研究了Perovskite型化合物La-Co-o体系的结构非完整性,并与其完全氧化催化活性相关联。该体系的结构式为:{La_1-x□x}-{[Co_(1-y)~(2+)Co_y~(3+)]_(1-v)□_v}_(1/2){[CO_(1-z)~(3+)Co_z~(4+)]_(1-w)□_w}_(1/2){O_(3-δ)□_δ}。结构中A位、B位和O位均存在空位。适当的空位可使B位钴的平均原子价高于+3,此时钴原子产生歧化作用,位于晶胞中(000)和(1/2 1/2 1/2)两个位置上的钴的平均原子价不相等。它们的差值越大,完全氧化催化活性越高。     

关于Hale问题

本文推广了林振声关于 Hale 问题的解答,利用微分系统的指数型三分性给出了弱概周期微分系统中心积分流形的存在性定理.     

毫米波圆柱波导自由电子激光放大器的数值模拟

本文以单粒子理论为基础，在不计空间电荷效应的近似条件下推导了带轴向引导磁场的三维圆柱波导非线性模拟方程组。用CAGFEL程序计算、分析了在带入口区、常数摇摆器条件下两组不同物理参数的自由电子激光放大器的物理模型。计算结果可靠，物理图象合理。对于其中的第二组参数还着重考查了光波频率、输入功率和摇摆器场振幅改变对输出功率和效率的影响。上述这些计算结果对0．7MeV 自由电子激光放大器的设计和实验具有一定的参考价值。     

Ce0.9RE0.1P5O14晶体中Ce^3＋的发光寿命研究

利用时间相关单光子计数方法系统地测定了Ce_(0.9)RE_(0.1)P_5O_(14)晶体中Ce~(3+)的发光寿命。发现荧光寿命数值能够较好地说明双掺晶体中除Ce而外的其它稀土离子对Ce~(3+)的发光强度的增强或猝灭现象。     

卤化铅调整Tm3+/Yb3+共掺碲酸盐玻璃上转换发光研究

研究了卤化铅调整Tm3+/Yb3+共掺碲酸盐玻璃的热稳定性能、Raman光谱和上转换发光光谱,分析了Tm3+/Yb3+共掺氧卤碲酸盐玻璃的上转换发光机理.结果发现:混合卤化铅调整Tm3+/Yb3+共掺碲酸盐玻璃具有好的热稳定性能、低的声子能量、强的上转换蓝光.这表明混合卤化铅调整Tm3+/Yb3+共掺碲酸盐玻璃是一种上转换蓝光激光器的潜在基质材料.     

茶皂素定量测定方法 的研究

我们以 纯化的茶 皂贰为标准 品,采用光度法对 茶皂 素的定 量测定方 法进行 了研 究.以8% 的 香 草醛 乙 醇 溶 液 和 7 % 硫酸为 显 色剂,测 定波长 为 4 52.sn m,显色反应的 温度为 60 ℃、反 应 时间 为 15 分钟 为宜.本方法具有操作简 便,消耗试剂量少及重复性好等特 点.结果表 明本法 适 用于 工 业 分析中茶皂素的定量 测 定.