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项目支持。来自伊利诺伊大学香槟分校的Renske van der Veen教授及其同事左建民、Prashant K Jain、陈倩和Pinshane Huang已经获得了一个电子能量损失光谱仪（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已知能量的电子束通过被分析的薄样品传输时能量分布的变化。电子束和样品之间的每次相互作用都会产生能量的变化，这是材料的特征，因为能量会损失。这就像一个球在篮球场之类的表面上弹跳。每次反弹，一点点能量从球被转移到表面，连续的反弹越来越短。这种能量的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基本成分。研究人员仔细观察了能量损失的范围，确定了被电子束击中的原子的类型，以及每种类型的原子的数量。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，从而可以绘制出给定样品中各种成分的位置。从本质上讲，这是一种化学显微镜，能够在从飞秒到毫秒的极短时间尺度上，捕捉到纳米结构和软材料在温度、气体、电压或光诱导下发生化学转变的特定元素快照。这些能力使得在多相催化、聚合物物理、电化学电荷传输、生物功能界面和超快材料切换等领域的发现成为可能，这些领域在清洁能源生产、生物医学成像、柔性电子和信息存储等领域至关重要。此外，该工具是现场化学绘图的重要区域和国家资源。在UIUC材料研究实验室（MRL）安装EELS系统满足了对这些功能的大量需求，该实验室是全国公认的用户设施，为研究和培训下一代科学家和工程师提供了前沿环境电子显微镜的机会。光谱仪被用于各种课程，并通过研讨会和一个面向高中女生的项目进行推广。该建议旨在加强各级的研究和教育。光谱仪尤其影响了场致纳米颗粒表面和界面形成和重组的研究。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，它还用于控制远离平衡态的物质，如光致相变和光活性材料中的超快激子动力学。该奖项反映了美国国家科学基金会的法定使命，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.