Controlling the Electronic Structure of Metallic Nanoparticles using Surface Chemistry

在化学系大分子、超分子和纳米化学项目（MSN）的支持下，宾夕法尼亚州立大学的Benjamin Lear将表面化学合成和先进的化学分析工具结合起来，研究金属纳米颗粒的电子特性是如何被表面分子改变的。金属纳米粒子提供了独特的电子特性，构成了新医学治疗、高价值化学品制造和能量转换过程的基础。然而，目前有有限的手段来控制潜在的电子特性，从而控制其使用的效率和功率。李尔大学的研究团队正致力于开发新的化学手段，利用这些粒子表面的分子来控制和调节这些电子特性。他们专注于控制电子能被金属束缚的方式。这一基本性质支撑着我们熟悉的行为，如导电、热传导和光泽。测量金属纳米颗粒的磁性行为可以定量地了解这一基本特性。除了这项工作预期的技术影响外，李尔博士和他的学生还将创建一个网站，通过数据可视化为交流提供清晰的设计规则。由于科学传播的优势依赖于这种可视化，因此提高演示的有效性和清晰度将使同行科学家、政策制定者和公众受益。在这个奖项下，宾夕法尼亚州立大学本杰明·李尔领导的研究小组寻求开发一种框架，用于配体控制金属纳米颗粒的电子结构。基本的假设是，配金属界面的性质影响金属的费米能的位置以及在费米能处的态密度。这些性质是从粒子的泡利顺磁性和电子顺磁共振（EPR）谱的测量中提取的。该团队特别试图了解配体的影响如何随着结合模式、配体层的组成和金属纳米颗粒的大小而变化。该团队还试图利用脉冲EPR来理解金属电子态和配体电子态之间耦合的本质。通过系统地改变纳米颗粒表面的配体，并测量伴随的磁性变化，李尔小组正在开发一个框架，使其他科学家和工程师能够合理地控制金属纳米颗粒的行为，增加它们的效用。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。

With support from the Macromolecular, Supramolecular and Nanochemistry Program (MSN) in the Division of Chemistry, Benjamin Lear of Pennsylvania State University is combining surface chemical synthesis and advanced chemical analysis tools to study how the electronic properties of metal nanoparticles are altered by molecules at their surfaces. Metal nanoparticles provide unique electronic properties that form the basis of new medical treatments, manufacture of high value chemicals, and energy conversion processes. However, there are currently limited means by which to control the underlying electronic properties and, thereby, control the efficiency and power of their use. The Lear research team is working to develop new chemical means to control and tune these electronic properties, utilizing the molecules often present at the surface of these particles. They focus on controlling the number of ways that electrons can be held on the metal. This fundamental property underpins familiar behaviors like electrical conduction, thermal conduction, and luster. Measuring the magnetic behavior of metal nanoparticles provides quantitative insight into this fundamental property. In addition to the technical impacts expected from this work, Dr. Lear and his students will be creating a website that provides clear design rules for communication through visualization of data. Because the preponderance of scientific communication relies on such visualizations, increasing the effectiveness and clarity of presentation will benefit fellow scientists, policy makers, and the general public.Under this award, the research team led by Benjamin Lear at Pennsylvania State University seeks to develop a framework for ligand control over the electronic structure of metallic nanoparticles. The underlying hypothesis is that the nature of the ligand-metal interface influences the position of the Fermi energy of the metal as well as the density of states at the Fermi energy. These properties are extracted from measurements of the Pauli paramagnetism of the particles and electron paramagnetic resonance (EPR) spectra. The team specifically seeks to understand how the influence of the ligands changes with binding mode, composition of the ligand layer, and size of the metallic nanoparticles. The team also seeks to understand the nature of the coupling between metallic electronic states and ligand electronic states, using pulse EPR. By systematically varying the ligands at nanoparticle surfaces, and measuring accompanying changes in magnetic properties, the Lear group is developing a framework that could enable other scientists and engineers to rationally control the behaviors of metal nanoparticles, increasing their utility.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.