A compressed-sensing ultrafast transmission electron microscope for single-shot nanometer and picosecond imaging of irreversible structural dynamics in action

许多不可逆的瞬态结构现象反映了材料中的重要机制。这些事件的真实的时间直接成像（即，事件发生的实际持续时间）在许多科学领域都有突破性的进展，并带来诱人的实际价值。然而，由于这些事件的不可重复性，它们的皮秒时间变化与微秒演变以及它们的纳米级空间尺度，这个目标本质上是具有挑战性的。到目前为止，成像仪器的发展还没有跟上。在现有的技术中，电影模式动态透射电子显微镜（MM-DTEM）最有潜力实现这一目标。然而，它目前受到纳秒时间分辨率和浅序列深度的限制。因此，新的单次超快电子成像仪器的发展是专门呼吁调查这些不可逆的瞬态结构动力学。 作为回应，我们要求通过RTI的资助购买一个自动控制系统，以开发压缩传感超快透射电子显微镜（CUTEM）。这种新型成像系统将具有纳米空间分辨率、皮秒时间分辨率和微秒记录窗口的单次拍摄实时成像。CUTEM将用于成像三个不可逆事件：激光诱导蒸发，非易失性存储材料的相变和纳米颗粒的自组装。所要求的设备是完全合适的，是必不可少的拟议研究。 拟议的研究具有令人信服的科学价值和深远的潜在应用。与目前最先进的MM-DTEM相比，CUTEM的时间分辨率可提高1000倍，层序深度可提高100倍。CUTEM还将为研究以前无法获得的材料物理和化学开辟新的途径。CUTEM与INRS的MM-DTEM机器（由CFI资助的基础设施）完全互补并协同集成，将显著提高PI，合作者和用户的整体研究能力。最后，拟议的研究将产生宝贵的战略优势，超过其他竞争集团在全球范围内，并使加拿大在这个高度竞争的领域处于领先地位。 PI和合作者的出色记录和互补专业知识将确保拟议项目的快速进展和整体成功，并最有效和最勤奋地使用所需设备。该计划还吸引了国家和国际一流研究所不同领域的11个主要用户。除了其科学价值，这些研究活动将提供最好的培训环境，以吸引和留住高素质的人员（HQP），为他们未来的职业生涯获得高度适销对路的技能。CUTEM将是一个完美的平台，以促进和加强公平，多样性和包容性的HQP培训。

Many irreversible transient structural phenomena reflect important mechanisms in materials. Direct imaging of these events in real time (i.e., the actual duration of the event's occurrence) promises breakthrough advances in many scientific fields and brings attractive practical merits. However, this goal is inherently challenging due to the non-repeatability of these events, their picosecond temporal changes with microsecond evolution, and their nanoscopic spatial scales. Thus far, the development of capable imaging instruments has not kept up. Among existing techniques, movie-mode dynamic transmission electron microscopy (MM-DTEM) has the most potential to accomplish this goal. However, it is currently limited by its nanosecond temporal resolution and shallow sequence depth. Hence, the development of new single-shot ultrafast electron imaging instruments is specifically called on for investigating these irreversible transient structural dynamics. In response, we request to purchase an automated control system via this RTI grant, to develop compressed-sensing ultrafast transmission electron microscopy (CUTEM). This novel imaging system will feature single-shot real-time imaging at nanometer spatial resolution, picosecond temporal resolution, and a microsecond recording window. CUTEM will be applied to imaging three irreversible events: laser-induced vaporization, phase transition of non-volatile memory materials, and self-assembly of nanoparticles. The requested equipment is perfectly suited and is indispensable to the proposed research. The proposed research has compelling scientific merits and far-reaching potential applications. Compared with the state-of-the-art MM-DTEM, CUTEM will enhance the temporal resolution by 1000 and the sequence depth by 100. CUTEM will also open new avenues for studying previously inaccessible physics and chemistry in materials. Fully complementary and synergistically integrated to the MM-DTEM machine (a CFI-funded infrastructure) at INRS, CUTEM will significantly enhance the overall research abilities of the PI, the collaborator, and users. Finally, the proposed research will generate precious strategic advantages over other competing groups worldwide and place Canada in a leading position in this highly competitive field. The excellent track records and complementary expertise of the PI and the collaborator will ensure fast progress and overall success of the proposed program as well as make the most efficient and diligent use of the requested equipment. The proposed program has also attracted 11 major users in diverse fields at national and international premier institutes. Beyond its scientific merits, these research activities will provide the best possible training environment to attract and retain highly qualified personnel (HQP) for obtaining highly marketable skills for their future careers. CUTEM will be a perfect platform to promote and reinforce equity, diversity, and inclusion in HQP training.