MRI: Development of a high energy-loss electron spectrometry system with improved detection sensitivity for an advanced electron microscope

扫描透射电子显微镜中的电子能量损失谱（EELS）已成为材料表征的重要工具。EELS可以提供有关化学成分和键合的信息，这与几个大型设施中可用的同步加速器X射线方法产生的信息相似。在这个研究项目中，将开发一种新型的EELS系统，它比现有系统更通用，可以检测更多的元素。它还将具有大大提高空间分辨率的优点，可达到纳米级，这比同步加速器源所能实现的要好得多。新的EELS系统有效地将（扫描）透射电子显微镜转换为同步加速器设施的等效物，但具有更高的空间分辨率。开发的这种仪器将影响从半导体到先进合金的材料科学广泛领域的广泛研究活动。它不仅支持利哈伊内部的项目，还支持其他大学、政府实验室和工业界的项目。开发的知识将通过PI/co-PI教授的课程向许多利哈伊学生展示，并向利哈伊显微镜学校的众多行业/政府与会者展示。同步加速器和电子显微镜团体将组织一次联合研讨会，交流这一丰富的重叠研究领域的知识。新的EELS系统有四个主要组成部分：（1）具有改进的光学设计的EELS光谱仪，用于检测较高能量损失的电子，（2）超高灵敏度电子检测器，用于在高能量损失范围内检测较低的信号，（3）用于柔性电子探针控制的多功能扫描发生器和（4）集成软件平台，其不仅有效地控制光谱仪和检测器，而且有效地控制显微镜以记录高能量损失信号，同时保持高空间分辨率并允许能量过滤成像。新的高能量损失EELS系统将能够检测高达~ 13，000 eV的能量损失信号。这意味着新的EELS系统可以记录高达Se（Z = 34，包括所有3d过渡金属）的K电离边缘、高达Tl（Z = 82，包括所有镧系元素）的L边缘和高达U（Z = 92）的M边缘。可用于EELS分析的材料系统的调色板将扩大到包括例如用于各种催化应用的金纳米颗粒、具有重元素的高熵合金和稀土基发光二极管。通过这个开发项目创建的软件包将免费提供给未来的用户。这个奖项反映了NSF的法定使命，并被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

Electron energy loss spectrometry (EELS) in the (scanning) transmission electron microscope has become an essential tool for materials characterization. EELS can provide insight on chemical composition and bonding, which is similar information to that generated by synchrotron X-ray methods available at several large facilities. In this research project, a new type of EELS system will be developed, which is more versatile and can detect more elements than currently achievable in existing systems. It will also have the advantage of greatly improved spatial resolution down to the nanoscale, which is considerably better than can be achieved at synchrotron sources. The new EELS system effectively transforms the (scanning) transmission electron microscope into the equivalent of a synchrotron facility but with improved spatial resolution. This instrumentation developed will impact a wide range of research activities across broad sectors of materials science ranging from semiconductors to advanced alloys. It will support projects not only internal to Lehigh, but also from other universities, government labs and industry. The knowledge developed will be presented to many Lehigh students via classes taught by the PI/co-PIs and also to numerous industry/government attendees of the Lehigh Microscopy Schools. A joint symposium will be organized between the synchrotron and electron microscopy communities to exchange knowledge on this fertile overlapping research area.The new EELS system has four major components: (1) an EELS spectrometer with improved optics design for the detection of higher energy-loss electrons, (2) an ultra-high sensitivity electron detector for lower signal detection in the high-energy-loss range, (3) a multi-functionality scan generator for flexible electron probe control and (4) an integrated software platform to efficiently control not only the spectrometer and detector, but also the microscope to record high-energy-loss signals while maintaining high spatial resolution and allowing energy-filtered imaging. The new high-energy-loss EELS system will be able to detect energy-loss signals up to ~13,000eV. This means that K ionization edges up to Se (Z = 34, including all 3d transition metals), L-edges up to Tl (Z = 82, including all the lanthanoid series) and M-edges up to U (Z = 92) can be recorded by the new EELS system. The palette of materials systems that become accessible for EELS analysis will be broadened to include for example, gold nanoparticles for various catalytic applications, high entropy alloys with heavy elements and rare-earth based light-emitted diodes. The software packages created through this development project will be made freely available for future users.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.