Ultrafast Structural Dynamics in Materials at Atomic to Microscale Resolution

原子级至微米级分辨率的材料超快结构动力学

• 批准号: RGPIN-2014-04013
• 负责人: Siwick, Bradley
• 金额: $ 3.06万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=633536
• 关键词: Ultrafast; Structural; Dynamics; Materials; Atomic

In the coming years, innovation in materials physics will reside in our ability to understand and control the intimate relationships between the structure of materials and their properties, both at and far from equilibrium. This goal has been recognized as a Grand Challenge for the fundamental sciences in a recent US Department of Energy (DOE) report. This requires new tools, and the PIs research program is focused on the pioneering development of instruments and methods that can provide essential missing information on complex materials, and the structure and properties of systems far from equilibrium. This research program is expected to have a broad impact across all traditional scientific disciplines (Physics, Chemistry, Biology). In particular, the proposed studies are enabled by the very recent development of RF compressed ultrafast electron diffraction in the Siwick group at McGill. The orders of magnitude enhancement in instrumentation performance that RF compression provides has defined a new state-of-the-art for UED studies, a technique that has recently provided unprecedented views of atomic-level structural dynamics for several materials and demonstrated the ability to separate dynamical contributions that come from the reorganization of lattice structure from that which comes from changes in orbital occupancy (or charge density) through an ultrafast optically induced phase transition. Combined with the state-of-the-art ultrafast broadband reflectivity also available in the Siwick lab and the new Infrastructure for Advanced Imaging in the Montreal area (based on two one-of-a-kind dynamic and ultrafast transmission electron microscopes) the PI has at his disposal a suite of advanced characterization methods is capable of interrogating time-evolving processes in materials near the level of detail that is available from the tools we use to study the equilibrium structure/properties of materials. Through this proposal the PI will apply these breakthrough tools and world world-class capabilities to measure material structures and properties during transformations to study the effects of structural changes on material functionalities and the dynamics of optical excitation in materials on their nature scales of length (nm), time (fs–ps) and energy (meV) simultaneously. These tools will be employed to address a number of target problems of high impact, including (but not limited to): 1. The respective role of electron-electron correlations, orbital selection and lattice distortions in the metal-insulator transitions of a broad class of strongly correlated oxides. 2. Optically induced structural dynamics in a range of 'light active' organic crystals from azobenzenes and charge transfer salts to protien crystals.

未来几年，材料物理学的创新将取决于我们理解和控制材料结构与其性质之间密切关系的能力，无论是处于平衡状态还是远离平衡状态。这一目标已被认为是基础科学的重大挑战。在美国能源部 (DOE) 最近的一份报告中，这需要新的工具，而 PI 研究计划的重点是仪器和方法的开拓性开发，这些仪器和方法可以提供有关复杂材料以及系统结构和特性的重要缺失信息。该研究计划预计将具有广泛的范围。对所有传统科学学科（物理、化学、生物学）的影响特别是，麦吉尔 Siwick 小组最近开发的射频压缩超快电子衍射使仪器性能提高了几个数量级。压缩为UED研究定义了一种新的最先进技术，该技术最近为多种材料提供了原子级结构动力学的前所未有的视图，并证明了分离来自重组的动力学贡献的能力晶格结构来自于通过超快光诱导相变改变轨道占用（或电荷密度），并结合了 Siwick 实验室和新的高级成像基础设施中提供的最先进的超快宽带反射率。在蒙特利尔地区（基于两台独一无二的动态和超快透射电子显微镜），PI 拥有一套先进的表征方法，能够在接近水平的情况下询问材料中的时间演化过程。通过此提案，PI 将应用这些突破性工具和世界一流的能力来测量转变过程中的材料结构和性能，以研究结构变化的影响。这些工具将同时用于解决许多具有高影响力的目标问题。包括（但不限于）： 1. 电子-电子相关性、轨道选择和晶格畸变在一大类强相关氧化物的金属-绝缘体转变中各自的作用。 2. 偶氮苯和偶氮苯等一系列“光活性”有机晶体中的光诱导结构动力学。电荷转移盐到蛋白质晶体。