MRI: Development of a Direct Detection Energy Loss Spectroscopy System

MRI：直接检测能量损失光谱系统的开发非技术性： 描述动态过程和反应-原子如何运动-对于解决能源、医学和纳米技术中的关键科学问题是必要的。为了满足这一需求，一个多学科的研究团队正在开发一种基于直接检测技术的新的超快光谱系统。这种最先进的系统能够在广泛的材料中动态研究电子和结构行为，并首次将原位电子能量损失谱引入电子显微镜市场，从而在电子显微镜领域产生深远的跨学科影响。德雷克塞尔大学位于美国众多顶尖机构的中心位置，确保了其与众多大学、实验室和用户的接触。开发团队拥有各种合作（包括在美国和国际），这使得新系统自动可见。教育和推广的机会包括利用NSF资助的Louis Stokes少数民族参与联盟（LSAMP）计划，招募少数民族学生在电子显微镜的背景下接受培训和教育，并利用德雷克塞尔著名的合作工程教育计划。技术支持：能量损失光谱特别适用于探测电子状态、能带结构和化学性质，以及提高材料的对比度。虽然电子光学的重大进步已经允许在原子水平上对结构和化学键进行精细探针分析，但透射电子显微镜（TEM）的下一个前沿依赖于成像动态过程和反应，超过标准视频帧速率。柱后能量过滤器和直接检测相机的关键发展使实验能够在精细的时间和空间尺度上进行;虽然这些发展单独推进了研究，但很明显，直接检测技术与能量过滤成像和光谱学的结合将具有实质性的好处。 到目前为止，这些技术还没有被组合，由于固有的不匹配之间的低剂量要求的直接检测应用和非常高的动态范围的电子能量损失谱（EELS）。该仪器开发活动集成了一个直接检测相机系统和一个高分辨率光谱仪，以允许在低电子剂量和高速度下进行原位EELS。这种前所未有的组合提高了非弹性散射技术的分析灵敏度，并产生了亚纳米到原子空间尺度的成分和电子结构映射，以及低能量下的高速（每秒4000帧）检测，允许定量时间分辨数据采集快速过程。能量过滤系统和能量损失光谱的专业知识与原位和超快TEM的专业知识相结合，提供了对关键过程的洞察，并弥合了对各个学科中机制的理解差距，对（1）氧化物和半导体异质结构中的电荷介导性质（2）储能材料中的离子转移，（3）生物医学和软材料中的组装机制。

MRI: Development of a Direct Detection Energy Loss Spectroscopy SystemNontechnical: Characterizing dynamic processes and reactions---how atoms move--is necessary to tackle key scientific issues in energy, medicine, and nanotechnology. To address this need, a multidisciplinary team of researchers are developing a new ultrafast spectroscopy system based on direct-detection technology. This state-of-the-art system enables dynamic studies of electronic and structural behavior in a wide range of materials and represents the first time in situ electron energy loss spectroscopy is being introduced to the electron microscopy marketplace, thus creating far-reaching and interdisciplinary impacts in the field of electron microscopy. Drexel's central location among many of the nation's top institutions ensures exposure to myriad universities, laboratories, and users. The development team boasts various collaborations (both in the US and internationally), which gives the new system automatic visibility. Opportunities for education and outreach include leveraging the NSF-funded Louis Stokes Alliance for Minority Participation (LSAMP) program to recruit minority students to train and be educated within the context of electron microscopy and to take advantage of Drexel's renowned co-operative engineering education program. Technical: Energy loss spectroscopy is particularly useful to probe electronic states, band structure, and chemistry, and to improve contrast in materials. While significant advancements in electron optics have permitted fine probe analysis of structure and chemical bonding at the atomic level, the next frontier in transmission electron microscopy (TEM) relies on imaging dynamic processes and reactions beyond standard video frame rates. Key developments in post column energy filters and direct detection cameras have enabled experiments at fine temporal and spatial scales; while these developments have advanced research individually, it is clear that the combination of direct detection technology with energy filtered imaging and spectroscopy would have substantial benefits. To date, these techniques have not been combined due to the inherent mismatch between the low-dose requirements of the direct detection applications and the very high dynamic range of electron energy loss spectroscopy (EELS). This instrument development activity integrates a direct detection camera system and a high resolution spectrometer to allow for in situ EELS to be performed at low electron doses and high speeds. This unprecedented combination boosts the analytical sensitivity of inelastic scattering techniques and yields compositional and electronic structure mapping at sub-nanometer to atomic spatial scales, and high-speed (4000 frames per second) detection at low energies, permitting quantitative time-resolved data acquisition for rapid processes. The combination of expertise of energy filtering systems and energy loss spectroscopy with expertise in in situ and ultrafast TEM provides insight into key processes and bridges gaps in the understanding of mechanisms in various disciplines, with direct and specific impacts on (1) charge mediated properties in oxide and semiconductor heterostructures (2) ion transfer in energy storage materials, and (3) assembly mechanisms in biomedical and soft materials.