为了完成基金内容，最近一直在做非水性电解液电镀金属薄膜。但这个领域相比目前热的又红又紫的能源材料来讲，自然逊色颇多。于是想到了将电沉积薄膜与锂离子电池负极材料结合起来，虽然这方面的研究也是铺天盖地了，但这项研究所采用的电沉积工艺还是区别于传统的，所以获得的Sn基薄膜的形貌和结构也有所不同，这样就有了研究的必要性。于是，在胆碱基离子液体中进行了电沉积Sn薄膜的工艺研究，结构表征发现薄膜具有多孔不连续结构，并且薄膜表面自然氧化成SnO2，而与集流体接触的Sn发生了合金化，原位生成了Cu6Sn5，这种原位合金化作用可以进一步增强活性材料与集流体的结合强度，降低电池内阻。相关报道请参与最新刊登在j power source上的文章。Thanks for your attention! Non-aqueous electrodeposition of porous tin-based film as an anode for lithium-ion battery Journal of Power Sources,214 (2012) 200-207 http://www.sciencedirect.com/science/article/pii/S0378775312008191?v=s5
You did not get the answer because you did not ask the question properly. LAMMPS是一个模拟软件，不是一种条件；“薄膜的谐振”是什么？从来没有听说过。谐振的唯一含义是简谐振动，所有的分子或晶体中的原子在任何温度任何条件下都在振动，谈不上在xx条件下的谐振。 同时，简谐振动往往指某一种模式的下的振动，一种振动模式往往涉及多个原子。一个包含N个原子的分子，其振动模式是3N-6种。线性分子3N-5。那么这些模式是怎么得到的呢？有个东西叫“正则模式分析”normal mode analysis。是通过群论中的对称性操作得到的。 要想做振动分析，即分析振动模式并计算振动频率，有2种方式。 **一种是优化分子结构，在能量最低点计算总能量相对于每个原子位移的二级导，得到Hessian矩阵（二级导系数矩阵），然后正则模式分析得到每种简谐模式的振动频率。此方法适合于研究单个的分子在0K下,气态时的振动。但其实温度对分子内振动频率的影响可以忽略，分子间的强相互作用，比如氢键，对振动频率的影响不可忽略，但仍可以用这种方法研究2～3个分子的理想模型体系。 **第二种方法是做分子动力学模拟，然后从体系总的dipole moment的变化轨迹中通过傅立叶分析分析出来每种振动模式的偶极变化对总偶极变化的贡献，并计算出各种贡献的频率。此种方法适合研究凝聚态体系。此种振动对应于有限温度下的振动。虽然温度对振动频率的影响很小，但是凝聚态体系中分子间作用对振动频率的迁移(红移，蓝移)有一定作用。 具体使用哪种方法，要看你研究的体系是什么，目的是什么。 因为你提到薄膜，似乎你要研究研究固体无定形态内的红外拉曼光谱。这种凝聚态体系，当然使用第二种方法比较适合。可以使用LAMMPS， NAMD，GROMACS等分子模拟软件来做，但准确性较低，因为此类基于经典力场的分子模拟软件的准确度取决于力场的质量。力场是分子模拟软件用来计算体系能量的势函数模型，是一种比较粗糙的模型。由于大多数常用分子力场更在乎结构准确性，所以它们计算的频率——能量对结构的二阶导信息——非常差，误差一般在50～200cm-1.不过，尽管很大的绝对值偏差使得它们不适合于研究绝对振动频率，但是仍然可以用他们来帮助研究峰的指认，或者研究凝聚态体系中存在复杂分子间相互作用情况下对振动峰的影响，比如蓝移，红移。就是说关注的是相对信息，而非绝对信息。 如果你既是凝聚态体系，也要求计算的振动频率的绝对值很准确，你需要使用第一原理动力学模拟，它结合了第一原理的准确性，和分子模拟方法研究凝聚态体系中的振动的优越性。使用第一原理动力学来计算多肽的红外光谱是蛋白模拟方面的一个前沿热点。 其实，研究凝聚态体系未必一定要用分子动力学模拟方法。第一种方法也能为研究高分子体系的振动光谱提供很多有用信息。即单分子能量优化和振动频率计算。 第一种方法的优点在于体系简单，计算快速，结果准确。因为一般通常用量子化学(DFT/B3LYP)来计算分子的能量和振动频率。跑个gauss很快可以拿到结果。但是用它来研究凝聚态高分子体系，就有点困难。因为这种方法要求体系的能量必须优化到电子基态的局部能量最小点，最好是全局能量最小点。否则，出现负的频率，即“虚频”，那么此时包括虚频在内的所有的频率值都失去了物理意义。而体系一大，就很难做优化。怎么办？从高分子中提取片段，搭建一个小的，简单的理论模型化合物去计算频率。要求模型化合物体现出你真是体系的化学环境。并忽略温度，分子间相互作用对频率的影响，或者另外用单独的双分子模型去研究分子间作用对振动的影响。这要求很高的搭建理想模型的技巧，和对问题本质的深刻理解。 对于您这样的新手，我的建议是，从Gauss软件学起，计算一些简单分子的振动频率。逐渐培养起对能量，结构，振动的理解以后，再思考如何研究固体内的红外拉曼光谱。
Thermomechanical analysis of thin films on temperature-dependent elastomeric substrates in flexible heterogeneous electronics Thin Solid Films, Volume 518, Issue 6, 1 January 2010, Pages 1698-1702 Yongan Huang, Zhouping Yin, Youlun Xiong Abstract Thermomechanical analysis is presented to study the basic temperature effects on elastomeric substrate of flexible electronics. Strains of a films-on-substrate structure related with three key temperatures are given based on the interfacial continuum model. An improved strain model is given and compared with other two models. The role of the temperature-dependent effects is highlighted and adopted to design a flexible inorganic/organic heterogeneous structure subject to little thermal action. The sensitivity analysis of three key temperatures is investigated, by which proper selection of technological parameter for poly(dimethylsiloxane) fabrication may be determined to eliminate the variation of stress of the interface in circumstances with temperature varying severely. This work contributes to systemic reliability and compatibility, structural design and thermal management of flexible electronics.
最近，在Journal of Materials Chemistry杂志上接收了一篇文章，很高兴，和大家一起共享。 http://www.rsc.org/Publishing/Journals/JM/article.asp?doi=b917739f 在本文中，以透明柔性十钨酸铕/琼脂糖薄膜为研究对象，构建了一个便携式的酸碱气体响应性发光开关。 Title: Chemically Responsive Luminescent Switching in Transparent Flexible Self-supporting 9 -Agarose Nanocomposite Thin Films Abstract: Europium-containing polyoxometalates (Eu-POMs) is widely used for fabrication of the hybrid inorganic-organic luminescent materials. A few efforts have been devoted to develop active Eu-POM-based luminescent sensors and switches. In this study, highly transparent flexible self-supporting decatungsteuropate(EuW 10 )-agarose thin films were successfully fabricated by a facile hydrogel casting technique. It was identified that strong interaction between agarose and EuW 10 by hydrogen bonds at the hydroxyl sites and densely-packed 3D network structure of agarose in the gel state account for the homogenous distribution of EuW 10 , and good mechanical properties of the nanocomposite films. More importantly, the obtained thin films displayed strong red emission of Eu(III) ion, and the luminescence of these thin films was sensitive to the acid and base gases. When the thin films were exposed to HCl gas, their luminescence was sharply decreased, while the luminescence was recovered upon subsequent exposing the films to NH 3 gas. Such process could be repeated many times and a portable switch based on these thin films was proposed.
谁来讲十分钟： Holes block light in very thin films Nov 17, 2009 What happens if you drill an array of tiny holes into a metal foil and then measure how much light the holes allow through? It turns out as physicists discovered back in 1998 that much more is transmitted than if the light behaved like water passing though a screen. The light is absorbed by electrons on the surface of the metal, creating surface plasmons collective oscillations of conduction electrons that travel via the holes to the dark side of the foil, where they re-emit the light. A golden discovery Now, physicists in Germany have discovered that this phenomenon, known as extraordinary optical transmission, does not occur in foils that are thin enough to be semi-transparent to light. Instead, Bruno Gompf and colleagues at the University of Stuttgart found that punching holes in such films leads to a significant reduction in the amount of light that gets through. The findings could be useful for creating new kinds of polarization filters and other components for photonic circuits. Reduced transmission Gomp's team began by coating a glass plate with a gold film just 20nm thick. This should let about half the light through, which was confirmed by measuring the transmission as a function of wavelength. The team then used a beam of argon ions to etch a square array of 200nm diameter holes with a period of 300nm. Although this involved removing a significant amount of gold, the amount of transmitted light actually fell by a factor of about five at some wavelengths. To gain a better understanding of this surprising observation, the team repeated the measurement at various angles of incident light. The researchers found that the wavelength of the transmission minimum shifted at certain angles relative to the square array, which led them to analyse the effect in terms of plasmons propagating on a square lattice. And because the material is so thin, the team also had to assume that surface plasmons on either side of the film were coupled to each other making them different from the surface plasmons on thicker films responsible for extraordinary optical transmission. Random holes Putting all of this together, the team concludes that only certain damped short-range surface plasmons can be excited under these conditions, and that while such plasmons absorb light, they do not re-emit it. Furthermore, the team showed energy of such plasmons corresponds to the energy of light at the dip in the transmission spectrum. Gompf told physicsworld.com that the team is now investigating films with different thicknesses as well as arrays with different periodicities and holes that are randomly positioned. Because the transmission of such films depends so much on the wavelength and orientation of the incident light, he believes that such materials could be used to create tiny polarization filters and other components for photonic circuits. The work is reported in Physical Review Letters . About the author Hamish Johnston is editor of physicsworld.com
量子振动： 现有的技术条件下可以用激光把处于两个反射镜之间的超薄的振动薄膜（鼓膜）冷却到它的量子力学基态。（见图）。两篇理论文章预言一对振动薄膜可以像两个原子形成一个分子一样耦合起来，甚至能够演示纠缠。 薛定谔那只囚禁在生和死的量子叠加态上的猫是永远不可发生在现实中的。但是根据在2008年4日发表在 Physical Review Letters 和十月份发表在P hysical Review A 上的理论文章指出在不久的将来可以观测到另一种不同种类的宏观物体的量子效应一个在光腔中类似于鼓反射膜的振动。研究者证明了利用现有技术试验学家能够冷却一对这样的振动鼓膜到它们像一个两原子或者像一个纠缠态测量一个会立即影响另一个的状态。 奇怪量子行为对于电子或者分子是很普通的，但宏观物体并不具有。研究者通过论证大物体（特别是固态振动或者摇摆的系统）的量子行为以希望观察到从量子到经典的过渡。例如振荡的弹簧或单摆在原理上存在一个基态（即振幅最小的的状态）和一组就像原子的能级一样量子化的（不连续）的振幅。奇怪的量子预测是两个物体可以纠缠在一起，锁在同一个量子状态即不论两个物体相距多远测量一个会立即影响另一个的状态（这和相对论相矛盾），爱因斯坦嘲笑说这是距离的幽灵行为。 在今年三月来自Yale University 的 Jack Harris 和他的同事报道了一个用7cm的两端是镜子的光腔的实验。在光腔的中间他们悬挂了一个用厚度为50纳米的氮化硅做成的一平方毫米的薄膜（鼓膜）。这个薄膜（鼓膜）的表面能部分的反射并能自由的振动。Harris和他的团队试图利用一束激光照射光腔来冷却薄膜（鼓膜）到基态。那些因镜子和薄膜（鼓膜）反射阻塞的光子能够减少薄膜的振动而使其冷却到7微开（标准温度）的低温这是处于初始温度时振动的10，000分之一，但是还没有达到量子极限。 在 Physical Review A 上, 来自 在 Tucson now 的大学 Arizona 的Mishkat Bhattacharya and Pierre Meystre 更进了一步在理论上证明了一对这样的薄膜（鼓膜）可以形成一个类似分子的状态。他们把两个薄膜（鼓膜）中心对称的放入光腔并写下了他们的运动方程。因为两个鼓膜都和激光光子相互作用，所以就像用弹簧固定在墙上的两个物体被一个弹簧连接在一起而使它们有效地耦合在一起。这样产生不同振动频率的两个振动模式质心模（两个鼓膜的同向振动）和呼吸膜（两个鼓膜的反向振动） 带入实际的实验参数以后，研究者发现通过入射合适频率的激光这两个振动模式可以分别的被冷却。这两个鼓膜原子有效的结合成一个鼓膜分子，根据计算可以冷却到这个分子振动到它的基态。 来自Imperial College London 的 Michael Hartmann 和 Martin Plenio 在 Physical Review Letters 上发表文章证明应当可以制备这两个鼓膜长寿命的纠缠态。在他们的方案中这两个鼓膜以腔中心对称的放置，导致不同类型的振动模式。这个团队通过计算发现这两个振动模可以用两束激光同时冷却。 他们发现通过小心的选择激光频率，当模被冷却时，激光和鼓膜的相互作用恰好把两个鼓膜制备到它们的纠缠态。只要有激光纠缠态就存在。为了非破坏的验证纠缠，可以再用两束很弱的激光探测它们。来自Yale的Steven Girvin 和Harris在薄膜冷却方面合作。他认为这两个方案利用现在的实验技术能够在不久的将来在实验室里实现。他说：这是个能够产生很多神奇动力学的丰富的系统。 --Michelangelo D'Agostino 英文来自 http://focus.aps.org/story/v22/st16 参考文献: J. D. Thompson et al. , Strong Dispersive Coupling of a High-Finesse Cavity to a Micromechanical Membrane, Nature (London) 452 , 72 (2008) . Multiple Membrane Cavity Optomechanics M. Bhattacharya and P. Meystre Phys. Rev. A 78 , 041801 (issue of October 2008) Steady State Entanglement in the Mechanical Vibrations of Two Dielectric Membranes Michael J. Hartmann and Martin B. Plenio Phys. Rev. Lett. 101 , 200503 (issue of 14 November 2008)
标签: 薄膜
