Collaborative Research: FRG: Beyond Crystallography: Structure of Nanostructured Materials

非技术摘要：纳米技术的一个圣杯是通过在纳米尺度上设计原子结构来设计和制造具有某些理想性质的材料。这方面的一个巨大障碍是纳米结构问题：已建立的确定原子结构的定量方法不适用于纳米尺寸的物体。这个项目通过实验和理论的合作来解决这个问题。这些实验利用了美国国家用户设施中可用的强X射线和中子束，并结合了从数据中提取可靠结构信息的新的计算方法。此外，还将使用超快飞秒时间分辨电子衍射来研究中间态的局域结构，并将其与相同的计算基础设施相耦合，使我们能够首次定量地探测纳米颗粒激发态的局域结构。在这项研究中，将研究一些具有科学和技术意义的材料，包括量子点纳米颗粒和用于可写CD和DVD的相变材料。然而，理论和方法的发展将以免费软件的形式向更广泛的科学和教育界提供，以便这些方法能够得到广泛应用。除了培训研究生和本科生进行最先进的研究外，纳米技术将在6-12年级进入课堂，并将与市中心兰辛高中的埃弗雷特高中合作建造新的动手纳米技术模块。在他们的积极参与下，将为AP课程开发新的课程和课程内容。该项目由凝聚态物理和固态化学计划共同支持。技术摘要：纳米技术的一个圣杯是通过在纳米尺度上设计原子结构来设计和制造具有理想性能的材料。这方面的一个巨大障碍是纳米结构问题：已建立的确定原子结构的定量方法不适用于纳米尺寸的物体。这个合作项目通过使用新的方法来分析和模拟纳米材料的X射线和中子散射数据来解决这个问题。数据将进行傅立叶变换，以获得原子对分布函数(PDF)，该函数将使用将开发的新方法进行建模，例如将化学信息编码为模型中的几何约束。这种分析将扩展到电子衍射数据，并与超快技术相结合，在飞秒时间尺度上定量研究局部结构。正在研究的系统包括用于可写CD和DVD的新型电子和光学材料，如低维电荷密度波碲化物、量子点纳米粒子和相变材料。这里开发的方法将通过培训和免费软件向广大纳米技术科学家社区提供。除了培训研究生和本科生进行最先进的研究外，纳米技术将在6-12年级进入课堂，并将与市中心兰辛高中的埃弗雷特高中合作建造新的动手纳米技术模块。在他们的积极参与下，将为AP课程开发新的课程和课程内容。该项目由凝聚态物理和固态化学计划共同支持。

Non-technical abstract:A holy grail of nanotechnology is to design and build a material with some desirable property by engineering the atomic structure at the nanoscale. A huge impediment to this is the nanostructure problem: the fact that the established quantitative methods for determining atomic structure fail for nano-sized objects. This project addresses this problem with a collaboration of experiment and theory. The experiments utilize the intense beams of x-rays and neutrons available at US national user facilities combined with novel computational approaches for extracting reliable structural information from the data. In addition the local structure of intermediate states will be studied using ultra-fast femtosecond time-resolved electron diffraction, coupled to the same computational infrastructure, allowing us for the first time to probe quantitatively the local structure of excited states of nanoparticles. In this study a number of scientifically and technologically interesting materials will be studied, including quantum-dot nanoparticles and phase-change materials used in writable CD and DVDs. However, the theoretical and methodological developments will be made available to the wider scientific and educational community in the form of freely available software so the methods can be widely applied. In addition to training graduate and undergraduate students in state-of-the-art research, nanotechnology will be taken to the classroom in grades 6-12 and new hands-on nanotechnology modules will be built in collaboration with Everett High School, an inner city Lansing high school. A new curriculum and course content for an AP course will be developed with their active participation. This project is co-supported by the Condensed Matter Physics and Solid State Chemistry programs.Technical abstract:A holy grail of nanotechnology is to design and build a material with desirable properties by engineering the atomic structure at the nanoscale. A huge impediment to this is the nanostructure problem: the fact that the established quantitative methods for determining atomic structure fail for nano-sized objects. This collaborative project addresses this by using novel approaches for analyzing and modeling x-ray and neutron scattering data from nanomaterials. The data will be Fourier transformed to obtain the atomic pair distribution function (PDF) which will be modeled using novel approaches that will be developed such as encoding chemical information as geometrical constraints in the model. The analysis will be extended to electron diffraction data and combined with ultrafast techniques to study local structure quantitatively on femtosecond time-scales. The systems under study include novel electronic and optical materials such as low-dimensional charge-density wave tellurides, quantum-dot nanoparticles and phase change materials that are used in writable CDs and DVDs. The methods developed here will be made available to the broad community of nanotechnology scientists through training and free software. In addition to training graduate and undergraduate students in state-of-the-art research, nanotechnology will be taken to the classroom in grades 6-12 and new hands-on nanotechnology modules will be built in collaboration with Everett High School, an inner city Lansing high school. A new curriculum and course content for an AP course will be developed with their active participation. This project is co-supported by the Condensed Matter Physics and Solid State Chemistry programs.