基于铕取代多金属氧簇的手性发光液晶材料

The incorporation of europium-substituted polyoxometalate (PM) into chiral amphiphiles is attractive for the fabrication of multifunctional chiral luminescent liquid crystalline materials. Chiral amphiphiles acted as good promoters to trigger the achiral PM to show induced supramolecular chirality through electrostatic interactions, as illustrated by circular dichroism (CD) spectra. Differential scanning calorimetry (DSC), polarized optical microscopy (POM), and temperature-dependent X-ray diffraction (XRD) analysis confirmed that the organic/inorganic hybrid polyoxometalate complex exhibited thermotropic mesomorphic behaviors. In a cast film, the complex displayed intrinsic luminescence that could be adjusted by accurately controlling the temperature. The electrostatic encapsulation of PM with chiral mesomorphic promoters provides an effective method for constructing PM-based chiral luminescent liquid crystalline materials.     

O2和CO在Ni(111)表面的吸附活化

采用高分辨电子能量损失谱(HREELS)、俄歇电子能谱(AES)和低能电子衍射(LEED)研究镍单晶表面氧物种及CO与O₂的共吸附。实验结果表明,Ni(111)表面氧化后存在两种氧物种,位于54 meV能量损失峰的表面化学吸附氧物种和位于69 meV能量损失峰的表面氧化镍。首先,随着暴露氧量的增加,表面化学吸附氧物种的能量损失峰蓝移至58 meV;其次,通过真空退火及与CO相互作用考察,发现表面化学吸附氧物种较不稳定。在室温条件下,表面预吸附形成的表面化学吸附氧物种与CO共吸附,导致端位吸附CO增多,表明氧优先吸附在穴位上,随着CO暴露量的增加化学吸附氧物种与CO反应脱去;而表面氧化镍需在较高温度和较高CO分压下才能被CO还原。预吸附CO可被氧逐渐移去。     

蒙特卡洛法研究随机粗糙表面的光散射特性

本文采用蒙特卡洛(M-C)数值模拟,生成起伏高度满足高斯分布的随机粗糙表面。借助Kirchhoff近似,并在综合考虑辐射传输、光学及电磁学有关理论的基础上,利用M-C方法计算了符合高斯分布的一维随机粗糙表面的单次和多次光散射分布,模型结合射线追踪法考虑了粗糙表面的遮蔽效应。结果表明在考虑多次散射时,存在后向散射增强现象,该结论与实验结果相吻合,证明本文数值模拟方法的正确性。     

超薄Ag膜的椭偏光谱建模及解谱

用直流溅射法制备了6个不同厚度的超薄Ag膜。结合超薄Ag膜的结构特点,采用了Drude模型联合Lorentz Oscillator模型的解谱方法,得到1～6号样品的厚度分别为4.0,6.2,12.5,26.2,30.0和40.6 nm。从拟合结果的消光系数k图谱中发现,在1号到4号样品中分别于430,450,560和570 nm处出现了表面等离子体共振峰(SPR),随膜厚的增加共振峰宽化且峰位红移。最后,利用SPR理论计算出不同厚度Ag薄膜等离子体共振峰出现的位置,并和实验结果进行了比较。     

Excitation of Propagating Plasmons in Semi-Infinite Graphene Layer by Free Space Photons

By investigating the diffraction of plane waves by a semi-infinite solution for propagating surface plasmons in graphene, which can be excited graphene edge. The theoretical results are confirmed by numerical simulations. excite propagating surface plasmons in graphene where the graphene edge plays graphene layer, we present a rigorous by incident plane waves through the Our results reveal a convenient way to an important role.     

Influence of roughness on the detection of mechanical characteristics of low-k film by the surface acoustic waves

The surface acoustic wave （SAW） technique is a precise and nondestructive method to detect the mechanical charac- teristics of the thin low dielectric constant （low-k） film by matching the theoretical dispersion curve with the experimental dispersion curve. In this paper, the influence of sample roughness on the precision of SAW mechanical detection is inves- tigated in detail. Random roughness values at the surface of low-k film and at the interface between this low-k film and the substrate are obtained by the Monte Carlo method. The dispersive characteristic of SAW on the layered structure with rough surface and rough interface is modeled by numerical simulation of finite element method. The Young＇s moduli of the Black DiamondTM samples with different roughness values are determined by SAWs in the experiment. The results show that the influence of sample roughness is very small when the root-mean-square （RMS） of roughness is smaller than 50 nm and correlation length is smaller than 20 μm. This study indicates that the SAW technique is reliable and precise in the nondestructive mechanical detection for low-k films.     

光敏季铵盐Gemini表面活性剂a4-6-m在气/液界面的吸附

合成了3种不对称结构的季铵盐Gemini表面活性剂a4-6-m, 分子的一根疏水链是偶氮苯为端基的4个亚甲基链, 另一根是不同长度的脂肪链(m=12, 14, 16). 研究结果表明, 反式偶氮苯封端的a4-6-m在气/液界面上以直立方式排列, 偶氮苯端基间的π-π相互作用导致吸附分子较为紧密地排列, 但吸附层外表面含有偶氮苯成分使临界胶束浓度(cmc)时的表面张力(γcmc)较大. 紫外光激发使反式结构偶氮苯变为顺式结构, 这些极性较强的顺式偶氮苯夹杂在直立的烷烃链间, 增强的偶极-偶极相互作用促进了分子紧密排列, 使分子占据面积(Amin)略微减小. 增长脂肪链长度有助于降低临界胶团浓度和C20(使水的表面张力降低20 mN·m-1时所需的表面活性剂浓度), 但对γcmc影响不大.     

Gemini表面活性剂烷烃尾链在吸附和聚集过程中的疏水协同效应(英文)

以表面张力法测定了系列Gemini表面活性剂m-6-m以及对应单体表面活性剂CmTABr的临界胶束浓度(cmc)和降低水表面张力20mN·m-1需要的浓度(pC20).比较这些参数表明m-6-m胶束化和在界面吸附的能力均强于CmTABr,这被归结为Gemini表面活性剂烷烃尾链间的疏水协同效应.与不对称Gemini表面活性剂12-6-m比较,对称的Gemini结构更有利于表面活性剂的聚集和吸附.     

Gemini型表面活性剂疏水链中肉桂酸基团的光致二聚反应

采用紫外光谱、 红外光谱和质谱研究了Gemini型表面活性剂N,N'-二对丁氧基肉桂酰胺基胱氨酸钠(SDBCC)溶液的光化学反应过程和产物, 分析了SDBCC浓度对分子疏水链中肉桂酸基团光化学反应产物分布和光致二聚产率的影响. 结果表明, 在不同浓度下, SDBCC分子疏水链中的肉桂酸基团的光化学反应过程均以光致二聚反应为主, 且为分子内光致二聚产物. 但聚集体形成前后在光照过程中肉桂酸基团的光致二聚反应产率随SDBCC浓度的变化趋势不同, 聚集体形成前光致二聚反应产率随浓度的增加而增大, 聚集体形成后光致二聚反应产率随浓度的增大而减小. 综合光化学反应过程、 拓扑条件和聚集体结构进一步分析了胶束和囊泡的存在对SDBCC分子疏水链中肉桂酸基团光致二聚反应的影响.     

新型阴离子Gemini表面活性剂与非离子表面活性剂C10E6混合溶液的胶团化的研究

研究了烷基苯磺酸盐Gemini表面活性剂Ia与非离子表面活性剂C10E6溶液混合胶团中分子间的相互作用. 通过表面张力法测定了Ia 和C10E6不同比例不同温度下的临界胶束浓度(cmc). 结果表明, 两种表面活性剂以任何比例复配的cmc比单一表面活性剂的cmc都低, 表现出良好的协同效应. 传统型非离子表面活性剂C10E6、Gemini表面活性剂Ia及混合物的cmc都随着温度升高而降低. 而且, 任何配比的混合胶团中两种表面活性剂分子间的相互作用参数β都是负值, 这说明两种表面活性剂在混合胶团中产生了相互吸引的作用. 混合表面活性剂体系的胶团聚集数比单一Ia的大, 但比单一C10E6的小. 向Gemini表面活性剂Ia胶束中加入非离子表面活性剂C10E6会使胶束的微观极性变小.