MRI: Acquisition of an Electron Energy-Loss Spectrometer for In Situ Time-Resolved Chemical Mapping of Nanomaterials

该奖项由主要研究仪器和化学研究仪器计划支持。来自伊利诺伊大学厄巴纳-香槟分校的Renske货车der Veen教授及其同事Jian-Min Zuo、Prashant K Jain、Qian Chen和Pinshane Huang获得了一台电子能量损失谱仪（EELS），将其添加到动态环境透射电子显微镜（DETEM）中。电子能量损失谱仪测量通过被分析的薄样品传输的已知能量的电子束的能量分布的变化。电子束和样品之间的每次相互作用都会产生能量变化，这是材料的特征，因为能量会损失。这类似于在篮球场等表面上弹跳的球。每一次弹跳，球的一点能量就会转移到表面，连续的弹跳会越来越短。这种能量损失被称为非弹性事件。这种类型的测量使研究人员能够研究材料的元素成分。研究人员仔细观察了大量的能量损失，确定了被电子束击中的原子类型，每种类型的原子数量。由于该光谱仪安装在动态环境透射电子显微镜上，因此可以获得额外的信息，这些信息可以映射给定样品中各种成分的位置。本质上，这是一种化学显微镜，能够在飞秒-毫秒的非常短的时间尺度上捕获不断变化的纳米结构和软材料的元素特定快照，这些材料经历温度，气体，电压或光诱导的化学转化。这些能力使多相催化、聚合物物理、电化学电荷传输、生物功能界面和超快材料开关等领域的发现成为可能，这些领域在清洁能源发电、生物医学成像、柔性电子和信息存储等领域至关重要。此外，这一工具是进行实地化学绘图的重要区域和国家资源。对这些功能的大量需求通过将EELS系统安置在UIUC材料研究实验室（MRL）来满足，该实验室是一个国家认可的用户设施，它为研究和培训下一代科学家和工程师提供了机会。光谱仪被用于各种课程，并通过一个讲习班和一个面向高中女生的方案进行推广，该提案旨在加强各级的研究和教育。光谱仪特别影响场诱导的纳米粒子表面和界面的形成和重组的研究。该仪器还用于在剂量控制条件下对软材料和软硬界面进行成像，并用于离子扩散和电极/电解质相互作用的研究。此外，它还被用于控制远离平衡的物质，如光致相变和光敏材料中的超快激子动力学。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This award is supported by the Major Research Instrumentation and the Chemistry Research Instrumentation programs. Professor Renske van der Veen from University of Illinois Urbana-Champaign and colleagues Jian-Min Zuo, Prashant K Jain, Qian Chen and Pinshane Huang have acquired an electron energy-loss spectrometer (EELS) to be added to a dynamic environmental transmission electron microscope (DETEM). An electron energy loss spectrometer measures the changes in energy distribution of an electron beam of known energy that is transmitted through a thin sample being analyzed. Each interaction between the electron beam and the sample produces a change in energy that is characteristic of the material since energy is lost. This is resembles a ball bouncing on a surface such as a basketball court. With each bounce, a bit of energy from the ball is transferred to the surface and consecutive bounces are shorter and shorter. This loss of energy is referred to as an inelastic event. This type of measurements allow the researchers to investigate the elemental components of a material. With some care, and looking at a broad range of energy loss, the researchers determine the types of atoms, number of atoms of each type, being hit by the electron beam. Because this spectrometer is installed on a dynamic environmental transmission electron microscope, additional information is obtained that can map where various components are in a given sample. In essence this is a chemiscope capable of capturing element-specific snapshots of evolving nanostructures and soft materials undergoing temperature-, gas-, voltage-, or light-induced chemical transformations on very short time scales ranging from femtoseconds-milliseconds. These capabilities enable discoveries in heterogeneous catalysis, polymer physics, electrochemical charge transport, biofunctional interfaces, and ultrafast materials switching, which are critical for example in clean energy generation, biomedical imaging, flexible electronics, and information storage. Moreover, the tool is a vital regional and national resource for in situ chemical mapping. Large demand for these capabilities are met by housing the EELS system at the UIUC Materials Research Laboratory (MRL), a nationally recognized user facility, where it provides opportunities for research and for training the next generation of scientists and engineers in cutting-edge environmental electron microscopy. The spectrometer is used in various courses and in outreach through a workshop and a program reaching to high school girls.The proposal is aimed at enhancing research and education at all levels. The spectrometer especially impacts studies of field-induced formation and restructuring of nanoparticle surfaces and interfaces. The instrument is also used for imaging of soft materials and soft-hard interfaces under dose-controlled conditions and for investigations of ionic diffusion and electrode/electrolyte interactions. In addition, it is employed to control matter far from equilibrium such as that in photoinduced phase transitions and ultrafast exciton dynamics in photoactive materials.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.