光致变色多阶游程光存储研究

多阶游程存储是一种不改变光学系统而显著提高光存储容量和数据传输率的新方法.介绍了光致变色多阶游程存储原理和实验系统.提出了基于光致变色原理的多阶游程存储数学模型，该模型反映了记录符反射率与曝光功率、曝光时间之间的非线性关系，并在此基础上确定了光致变色多阶游程存储的写策略.基于650nm光致变色材料进行了4阶游程存储的动态实验.结果表明，实验中采用的650nm光致变色材料可用于多阶游程存储，采用的写策略能够有效地使记录信道线性化，利于采用适合线性系统的信号处理方法. 关键词： 多阶游程 光致变色 光存储 写策略     

大小周期正方格子复合结构的光子带隙特性

把具有宽完全带隙的粗锐复合的周期常数为a的二维正方格子再与周期常数为a₂的大周期简单正方格子复合，发现大周期正方格子起缺陷作用.并发现当a₂<5a时,缺陷态明显地随入射角度变化.此变化随a₂的增大而减少.用FDTD方法计算了其透射和反射谱,结果表明缺陷峰透射率与a₂的大小成反比.另外还发现: 缺陷峰结构与大周期正方格子的圆柱直径的关系曲线与a₂关系不大.通过调节大周期正方格子的圆柱的直径，可获得单 关键词： 光子晶体 光子能隙 复式结构 缺陷态     

非晶钛酸铋的晶化过程

利用差热分析、X射线衍射和透射电子显微镜等技术对溶胶-凝胶法合成的凝胶的晶化过程进行了分析，实验结果表明，Bi₄Ti₃O₁₂非晶凝胶晶化过程经历了四个过程：首先在433℃先形成了Bi₂O₃和TiO₂亚稳相，然后在488℃时TiO₂亚稳相与Bi₂O₃反应形成Bi，Ti复合氧化物亚稳相Bi₂T 关键词： 钛酸铋 铁电材料 溶胶凝胶 非晶 晶化过程     

外应力场下铁磁/反铁磁双层膜系统的铁磁共振性质

从系统能量出发，采用Smith和Beljers理论方法研究了铁磁/反铁磁双层膜系统在外应力场下的铁磁共振现象.本模型中铁磁薄层具有单轴磁晶各向异性和立方磁晶各向异性，而反铁磁层非常薄因而其能量可忽略.推导出了该系统的铁磁共振频率和频谱宽度的解析式.结果表明：外应力场仅在低磁场下对具有立方磁晶各向异性系统的铁磁共振有影响，且区分弱磁场和强磁场的临界场依赖于外应力场的方向. 关键词： 铁磁/反铁磁双层膜 交换偏置 铁磁共振 应力场     

Muonium formation in xenon and argon up to 60 atmospheres

Results of muon polarization studies in xenon and argon up to 60 atm are reported. In argon for pressures up to 10 atm, the muon polarization is best explained by an epithermalcharge exchange model. Above this pressure, the decrease inP _D and increase inP _L are ascribed to charge neutralization and spin exchange reactions, respectively, in the radiolysis track. Measurements with Xe/He mixtures with a xenon pressure of 1 atm indicate that the lost polarization in the pure xenon at this pressure is due to inefficient moderation of the muon. As the pressure in pure xenon is increased above 10 atm, we find thatP _L remains roughly constant andP _D begins to increase. The lost fraction may be due to the formation of a XeMu Van der Waals type complex, whileP _D is ascribed to XeMu⁺ formation. This suggests that spur processes appear to be less important in xenon than in argon.     

自由电子激光的医学应用

自由电子激光这种新型光源非常适合于医学应用。通过对医用自由电子激光器的简要介绍,探讨了自由电子激光与人体组织的相互作用及其在医学上的应用前景。     

Excitation spectra of one-dimensional spin-1/2 Fermi gas with an attraction

Using an exact Bethe ansatz solution, we rigorously study excitation spectra of the spin-1/2 Fermi gas (called Yang–Gaudin model) with an attractive interaction. Elementary excitations of this model involve particle-hole excitation, hole excitation and adding particles in the Fermi seas of pairs and unpaired fermions. The gapped magnon excitations in the spin sector show a ferromagnetic coupling to the Fermi sea of the single fermions. By numerically and analytically solving the Bethe ansatz equations and the thermodynamic Bethe ansatz equations of this model, we obtain excitation energies for various polarizations in the phase of the Fulde–Ferrell–Larkin–Ovchinnikov-like state. For a small momentum (long-wavelength limit) and in the strong interaction regime, we analytically obtained their linear dispersions with curvature corrections, effective masses as well as velocities in particle-hole excitations of pairs and unpaired fermions. Such a type of particle-hole excitations display a novel separation of collective motions of bosonic modes within paired and unpaired fermions. Finally, we also discuss magnon excitations in the spin sector and the application of Bragg spectroscopy for testing such separated charge excitation modes of pairs and single fermions.     

Amorphous High-Entropy Hydroxides of Tunable Wide Solar Absorption for Solar Water Evaporation

The high-entropy materials have raised much attention in recent years due to their extraordinary performances in mechanical, catalysis, energy storage fields. Herein, a new type of high-entropy hydroxides (e.g., NiFeCoMnAl(OH)_x) that are amorphous and capable of broad solar absorption is reported. A facile one-pot co-precipitation method is employed to synthesize these amorphous high-entropy hydroxides (a-HEHOs) under ambient conditions. The a-HEHOs thus obtained display widely tunable bandgap (e.g., from 2.6 to 1.1 eV) due to their high-entropy and amorphous characteristics, enabling efficient light absorbance and photothermal conversion in the solar regime. Further solar water evaporation measurements show that the a-HEHOs delivered a considerable energy conversion efficiency of 55%, comparable to black titanium oxides that are synthesized using more complex and expensive methods.     

正火和回火处理过程中W/Fe/RAFM钢接头W/Fe界面组织和剪切性能的演化

对热等静压(HIP)扩散焊制备的W/Fe/RAFM钢接头进行了正火和回火处理,以恢复其中RAFM钢的组织和性能.采用电子探针微分析器(EPMA)和掠入射X射线衍射(GIXRD)对W/Fe界面组织的演化进行了分析,采用剪切测试和扫描电镜(SEM)对接头连接性能的演化进行了测试和分析.结果表明,正火处理后,RAFM钢中的C...     

液态Sn-Cu钎料的黏滞性与润湿行为研究

金属熔体的黏度和表面张力都是与液态结构相关的敏感物理性质, 且存在一定的相互关系. 对于微电子封装材料而言, 黏度和表面张力均是影响其工艺性能的重要参量. 本文利用回转振动式高温熔体黏度仪测量了Sn-xCu (x = 0.7, 1.5, 2)钎料熔体在不同温度下的黏度值, 发现在一定温度范围内钎料熔体的黏度值存在突变, 可划分为低温区和高温区. 在各温区内, 黏温关系很好地符合Arrhenius方程, 在此基础上讨论了液态钎料的结构特征和演变规律. 同时, 利用黏度值计算了液态Sn-xCu钎料在相应温度下的表面张力, 并通过Sn-xCu钎料在Cu基板上的润湿铺展实验对计算结果进行验证. 结果显示, 润湿角和扩展率的测试结果与表面张力的计算结果具有很好的一致性, 表明通过熔体黏度值来计算锡基二元无铅钎料合金表面张力并评估其润湿性能的方法是可行的. 关键词： Sn-Cu钎料 黏度 表面张力 润湿性