Controlling the Electronic Structure of Metallic Nanoparticles using Surface Chemistry

在化学系大分子、超分子和纳米化学计划(MSN)的支持下，宾夕法尼亚州立大学的本杰明·李尔正在结合表面化学合成和先进的化学分析工具，研究金属纳米颗粒表面分子如何改变其电子性质。金属纳米颗粒提供独特的电子特性，这些特性构成了新的医疗方法、高价值化学品制造和能源转换过程的基础。然而，目前控制基本电子性质并由此控制其使用的效率和功率的手段有限。李尔研究小组正致力于开发新的化学方法来控制和调节这些电子性质，利用这些粒子表面经常存在的分子。他们专注于控制电子在金属上可以保持的方式的数量。这一基本特性支撑着常见的行为，如导电、热传导和光泽。测量金属纳米颗粒的磁性行为提供了对这一基本性质的定量洞察。除了这项工作预计会产生的技术影响外，李尔博士和他的学生还将创建一个网站，为通过数据可视化进行交流提供清晰的设计规则。由于科学交流的优势依赖于这种可视化，增加演示的有效性和清晰度将使同行科学家、政策制定者和普通公众受益。在这一奖项下，宾夕法尼亚州立大学的本杰明·李尔领导的研究小组寻求开发一种配体控制金属纳米颗粒电子结构的框架。基本的假设是，配体-金属界面的性质影响金属的费米能量的位置以及费米能量处的态密度。这些性质是通过测量粒子的泡利顺磁性和电子顺磁共振(EPR)谱来提取的。该团队特别寻求了解配体的影响如何随着结合模式、配位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来了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，李尔团队正在开发一个框架，使其他科学家和工程师能够合理控制金属纳米颗粒的行为，增加它们的实用性。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。

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.