Ultrafast Electron Scattering at Low Temperatures

低温下超快电子散射

• 批准号: RTI-2019-00586
• 负责人: Siwick, Bradley
• 金额: $ 9.07万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Research Tools and Instruments
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=665360
• 关键词: Ultrafast; Electron; Scattering; Low; Temperatures

There is currently an enormous, world-wide effort directed at the development and application of new experimental methods that make it possible to directly ‘watch' the time-evolving structure of matter. These approaches combine state-of-the-art femtosecond lasers (see Nobel Prize in Physics, 2018) and sources of either ultrashort Xray or electron pulses to acquire time-resolved diffraction/scattering patterns and images. At the highest time-resolution achievable in these instruments, atomic motion is essentially frozen during an observation and one can completely follow the fundamental dynamics to produce a "molecular movie"; the experimental equivalent of a molecular dynamics simulation. It is possible to watch chemical bonds break/form and directly determine transition-state structures for even complex reactions, to follow phase transition dynamics uncovering the deep connections between the structure and properties of materials, and even to obtain an atomic-level understanding of protein function with these approaches. ***This proposal is focused on the further development of the World's most powerful ultrafast electron scattering instrument, designed, built and operating at McGill University. We are requesting equipment that builds on previous successes and enables ultrafast electron scattering at cryogenic temperatures. This new capability will open up an enormous new 'scientific space' to be explored. With the requested equipment, we expect to be able to shed new light on materials phenomena as diverse as superconductivity, charge density waves, thermoelectricity, photovoltaicity and carrier mobility in semiconductors and metals. We will be in a position to investigate the complex interplay between strong, multi-orbital electronic correlations, structural distortions, charge and orbital order across a range of strongly correlated material where this physics determines properties (transition metal oxides, pyrochlore oxides, manganites and cuprates), and there is a possibility of discovering new photoinduced phases and avenues for optical control of complex materials, a topic at the forefront of materials research.

目前，世界范围内正在付出巨大的努力来开发和应用新的实验方法，使直接“观察”物质随时间演化的结构成为可能。 这些方法结合了最先进的飞秒激光器（参见 2018 年诺贝尔物理学奖）和超短 X 射线或电子脉冲源，以获取时间分辨的衍射/散射图案和图像。 在这些仪器可实现的最高时间分辨率下，原子运动在观察过程中基本上被冻结，人们可以完全遵循基本动力学来制作一部“分子电影”；分子动力学模拟的实验等效项。 可以观察化学键的断裂/形成，并直接确定复杂反应的过渡态结构，跟踪相变动力学，揭示材料结构和性质之间的深层联系，甚至通过这些方法获得对蛋白质功能的原子级理解。 ***该提案的重点是进一步开发世界上最强大的超快电子散射仪器，由麦吉尔大学设计、建造和运行。我们要求设备能够在以往的成功基础上实现在低温下的超快电子散射。这种新能力将开辟一个巨大的新“科学空间”供探索。 借助所需的设备，我们希望能够对半导体和金属中的超导性、电荷密度波、热电性、光伏性和载流子迁移率等多种材料现象提供新的认识。 我们将能够研究一系列强相关材料中强、多轨道电子相关性、结构畸变、电荷和轨道顺序之间的复杂相互作用，这些材料的物理特性决定了这些材料的特性（过渡金属氧化物、烧绿石氧化物、锰酸盐和铜酸盐），并且有可能发现新的光致相和复杂材料光学控制的途径，这是材料领域的前沿课题 研究。