Probing the Vibrational States of Surface Sites on Catalytic Nanoparticles with Atomic Resolution Electron Energy-Loss Spectroscopy

用原子分辨率电子能量损失谱探测催化纳米粒子表面位点的振动状态

• 批准号: 2109202
• 负责人: Peter Crozier
• 金额: $ 48万
• 依托单位: Arizona State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-07-15 至 2025-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2109202&HistoricalAwards=false
• 关键词: Probing; Vibrational; States; Surface; Sites

With the support of the Chemical Measurement and Imaging (CMI) Program in the Division of Chemistry, and partial co-funding from the Catalysis Program in the Division of Chemistry and the Atomic, Molecular, and Optical Physics Program in the Division of Physics, Professor Peter Crozier of Arizona State University is studying development of a new imaging tool to measure the vibrations of atoms on the surface of small particles, with the latter being targeted as catalysts for important chemical conversion processes. The atoms on the surface of a material are constantly vibrating in a variety of different ways, with those different types of vibrations corresponding to different vibrational pathways, referred to as modes. These vibrational modes of the atoms on the surface of a material can help transfer energy to molecules bound to the surface of the material, which may drive catalytic chemical changes in the molecular structure of the surface-bound molecules. However, there are limited methods for gaining information about vibrational modes across the surface of small particles. Professor Crozier will develop and apply novel microscopy techniques that use electrons for the imaging process so as to detect and study the characteristics of surface vibrational modes on very small particles. The fundamental principles anticipated from this study have the potential for long-term impact not only in catalysis but also in other areas of materials and life science. To engage students, teachers, and the public in this research, an educational module entitled “Good Vibrations” will be developed, which will link the area of atomic-level vibrations to vibrational sound waves found in music. A web-based application will be developed that allows students and the public to decompose music passages into fundamental vibrational (harmonic) modes. By incorporating music from contemporary artists, the team hopes to engage high school students in the excitement of vibrational science and generate enthusiasm for careers in science, technology, engineering, and mathematics. The goal of this project is to probe and develop a fundamental understanding of vibrational states at distinct surface sites on catalytic nanoparticles with atomic resolution. To improve our understanding of the vibrational energy exchange process, it is necessary to have information on the local vibrational modes that exist at surface sites. Vibrational dynamics on nanoparticle surfaces are not well understood, in part because there have been no methods to perform atomic resolution probing of surface vibrational modes. The Krozier team will address this deficiency by developing novel approaches to vibrational electron energy-loss spectroscopy (EELS) in the scanning transmission electron microscope (STEM) using the impact component of inelastic electron scattering. Electron scattering in STEM carries information about vibrational states in a manner similar to inelastic neutron scattering, but it can provide atomic resolution. Moreover, the signal may be associated with short wavelength modes that are most sensitive to atomic defects. Overall, this research has the potential to provide a useful new vibrational description of the surfaces of catalysts.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.

在化学系化学测量和成像(CMI)计划的支持下，以及化学系催化计划和物理系原子、分子和光学物理计划的部分共同资助下，亚利桑那州立大学的Peter Crozier教授正在研究开发一种新的成像工具来测量小颗粒表面原子的振动，后者被用作重要化学转化过程的催化剂。材料表面的原子不断以各种不同的方式振动，这些不同类型的振动对应于不同的振动路径，称为模式。材料表面原子的这些振动模式可以帮助将能量转移到与材料表面结合的分子，这可能会推动表面结合分子的分子结构发生催化化学变化。然而，获取小颗粒表面振动模式信息的方法有限。克罗泽教授将开发和应用新的显微镜技术，使用电子进行成像过程，以检测和研究非常小颗粒的表面振动模式的特征。这项研究预期的基本原理不仅在催化方面，而且在材料和生命科学的其他领域都有潜在的长期影响。为了让学生、教师和公众参与到这项研究中来，将开发一个名为“良好振动”的教育模块，它将把原子级振动的区域与音乐中的振动声波联系起来。将开发一个基于网络的应用程序，允许学生和公众将音乐段落分解为基本的振动(谐和)模式。通过融合当代艺术家的音乐，该团队希望让高中生参与到振动科学的兴奋中来，并激发他们对科学、技术、工程和数学职业的热情。这个项目的目标是探索和发展对具有原子分辨率的催化纳米颗粒上不同表面位置的振动状态的基本理解。为了提高我们对振动能量交换过程的理解，有必要了解存在于表面位置的局部振动模式。纳米颗粒表面的振动动力学还没有被很好地理解，部分原因是还没有方法来进行表面振动模式的原子分辨探测。Krozier团队将利用非弹性电子散射的影响成分，在扫描电子显微镜(STEM)中开发振动电子能量损失谱(EELS)的新方法，以解决这一不足。STEM中的电子散射以类似于非弹性中子散射的方式携带有关振动态的信息，但它可以提供原子分辨率。此外，该信号可能与对原子缺陷最敏感的短波长模有关。总体而言，这项研究有可能为催化剂表面提供有用的新的振动描述。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。