MRI:Development of a femtosecond high brightness electron beam source for time-resolved electron diffraction and imaging

MRI：开发用于时间分辨电子衍射和成像的飞秒高亮度电子束源

• 批准号: 1126343
• 负责人: Chong-Yu Ruan
• 金额: $ 96.82万
• 依托单位: Michigan State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-10-01 至 2016-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1126343&HistoricalAwards=false
• 关键词: MRI; Development; femtosecond; brightness; electron

Technical abstractA novel high flux rf enabled femtosecond electron diffraction microscope will be developed to allow unprecedented resolution and sensitivity for studying underlying physical and chemical processes associated with nanoscale complex materials and macromolecules. These efforts rest upon innovative solutions to the space-charge broadening issues associated with high-brightness beams that lead to degradation of the temporal resolution and beam quality, and overcoming the limitation in the photo-gun design to provide a high-brightness coherent electron source. Our proposed new technologies include incorporating an rf cavity to recompress electron pulses that are degraded by space-charge broadening; optimization of the coherent electron source through design and implementation of a laser pulse shaper to control photoemission; and a real-time electron bunch imager to provide feedback control. Scientific and technological progress will be enabled by a unique team of experts in accelerator and beam physics, rf cavity design and implementation, femtosecond laser and ultrafast electron diffraction technologies, and theoretical modeling for the development of this unique fs electron beam system. Our ultimate goal is to be able to videograph single-particle and single-site events by ultrafast diffraction with 2-3 orders of magnitude enhancement in the beam brightness compared with the current state-of-the art ultrafast electron diffraction systems. Reaching a nano-probe limit will open up new research areas including those identified by a recent Academy of Sciences report, such as: "single-site" heterogeneous catalysis, charge dynamics in nanocrystal quantum dots relevant for photovoltaics, energy transfer through nanostructures relevant for information processing and sensing, the emergence of electron correlation in strongly correlated materials and heterostructures, and energy transduction at the nanoscale. The realization of this table-top scale fs electron beam system will enable unprecedented material research capabilities at a wide variety of University laboratories both at Michigan State University and in the broader community. A nanoscience movie will be produced that provides K-12 students with an engaging view of nanoscience and the way in which graduate students drive the process of constructing a forefront user facility to understand nanoscience and nanotechnology.Nontechnical abstractAn innovative ultrafast electron beam system will be developed to allow unprecedented resolution and sensitivity for imaging atoms, molecules and nanoparticles "in the act" at the femtosecond (fs) timescale (1 fs=1/1000,000,000,000,000 second). The breakthrough in the advanced capabilities is made possible by solving the space-charge effects associated with high-density electron pulses causing degradation of the beam quality for high-resolution imaging. Our proposed new technologies include accelerator technology to compress high-density electron beam to the fs timescale with a radio-frequency compressor, innovative photoelectron source design incorporating fs laser pulse shaping, and advanced high-speed electron beam characterization to provide instant feedback control. Scientific and technological progress will be enabled by a unique team of experts in accelerator and beam physics, radio-frequency compressor design and implementation, fs laser technologies, and theoretical modeling for the development of this unique fs electron imaging system. Our ultimate goal is to be able to videograph the molecular events with high fidelity and fs speed with a nanometer scale probe. Realization of this goal will bring a completely new dimension to unveil material properties and chemical reactions underlying the forefront of nanotechnology and nanoscience including those identified by a recent Academy of Sciences report, such as biochemical reactions and catalysis, solar energy harvesting, complex material functions, and information processing on the nanometer scale. The realization of this table-top scale fs electron beam system will enable unprecedented material research capabilities at a wide variety of University laboratories both at Michigan State University and in the broader community. A nanoscience movie will be produced that provides K-12 students with an engaging view of nanoscience and the way in which graduate students drive the process of constructing a forefront user facility to understand nanoscience and nanotechnology.

一种新型的高通量射频飞秒电子衍射显微镜将被开发出来，为研究与纳米级复杂材料和大分子相关的潜在物理和化学过程提供前所未有的分辨率和灵敏度。这些努力取决于创新解决与高亮度光束相关的空间电荷展宽问题，该问题导致时间分辨率和光束质量下降，并克服光电枪设计中的限制，以提供高亮度相干电子源。我们提出的新技术包括纳入射频腔来重新压缩因空间电荷展宽而退化的电子脉冲；通过设计和实现激光脉冲整形器来优化相干电子源以控制光电发射；和一个实时电子束成像仪提供反馈控制。在加速器和束流物理、射频腔设计和实现、飞秒激光和超快电子衍射技术以及为开发这种独特的fs电子束系统而进行的理论建模方面，一支独特的专家团队将推动科学和技术的进步。我们的最终目标是能够通过超快衍射拍摄单粒子和单点事件，与目前最先进的超快电子衍射系统相比，光束亮度提高了2-3个数量级。达到纳米探针的极限将开辟新的研究领域，包括最近科学院报告确定的领域，例如：“单位点”异相催化，与光伏相关的纳米晶体量子点中的电荷动力学，通过与信息处理和传感相关的纳米结构的能量转移，强相关材料和异质结构中电子相关性的出现，以及纳米尺度上的能量转导。这种桌面级电子束系统的实现将使密歇根州立大学和更广泛的社区的各种大学实验室具有前所未有的材料研究能力。将制作一部纳米科学电影，为K-12学生提供纳米科学的迷人视角，以及研究生如何推动构建前沿用户设施的过程，以了解纳米科学和纳米技术。将开发一种创新的超快电子束系统，以在飞秒（fs）时间尺度（1fs =1/1000,000,000,000,000秒）下对原子、分子和纳米粒子“在活动”进行成像，从而实现前所未有的分辨率和灵敏度。通过解决与高密度电子脉冲相关的空间电荷效应，导致高分辨率成像的光束质量下降，先进功能的突破成为可能。我们提出的新技术包括加速器技术，利用射频压缩机将高密度电子束压缩到fs时间尺度，创新的光电子源设计，结合fs激光脉冲整形，以及先进的高速电子束表征，提供即时反馈控制。科学和技术的进步将由一个独特的专家团队在加速器和束物理，射频压缩机的设计和实施，fs激光技术和理论建模的发展这一独特的fs电子成像系统。我们的最终目标是能够用纳米尺度的探针以高保真度和fs速度拍摄分子事件。实现这一目标将带来一个全新的维度，揭示纳米技术和纳米科学前沿的材料特性和化学反应，包括最近科学院报告确定的生物化学反应和催化、太阳能收集、复杂材料功能和纳米尺度上的信息处理。这种桌面级电子束系统的实现将使密歇根州立大学和更广泛的社区的各种大学实验室具有前所未有的材料研究能力。将制作一部纳米科学电影，为K-12学生提供纳米科学的迷人视角，以及研究生如何推动构建前沿用户设施的过程，以了解纳米科学和纳米技术。