Using conduction spin electron spectroscopy as a sensitive and selective probe for understanding the surface chemical control over the electronic behavior of metallic nanoparticles

化学系的大分子、超分子和纳米化学项目支持宾夕法尼亚州立大学帕克分校的本杰明·李尔博士。李尔博士的项目描述了金属纳米颗粒与其周围环境之间的相互作用。金属纳米颗粒是极其微小的金属颗粒，其中至少有一个结构尺寸（长度，宽度或厚度）在纳米尺寸范围内（1至100纳米）。金属纳米颗粒具有广泛的应用，包括化学制造、电子设计和癌症治疗。在这些应用中，纳米颗粒表面附近的环境可以是非常多样化的。人们对这些环境变化如何影响纳米粒子理想的电子特性知之甚少。本项目开发并应用了一种新技术来了解周围环境对金属纳米粒子电子特性的影响。这项研究的结果将导致纳米颗粒与周围环境相互作用优化的新先进技术的发展。作为该项目的一部分，李尔博士让多名高中生在他的实验室工作，这是宾夕法尼亚州立大学外展项目的一部分，该项目为来自“风险”学校的学生提供培训。该项目研究了表面化学和化学环境对小（直径约2纳米）金纳米粒子（AuNPs）电子结构的影响。研究了大量的表面化学成分，并使用x射线粉末衍射（XRD）、透射电子显微镜（TEM）、核磁共振（NMR）、电化学和传导电子自旋共振（CESR）研究了纳米颗粒的性质。CESR为金属核内靠近费米能量的电子所经历的电子环境提供了敏感和选择性的探测。本项目建立了CESR对表面化学变化的响应机制。此外，本项目通过探索溶剂、电化学电位和配体变化的影响，探索AuNPs对局部环境变化的敏感性。详细了解电子学和金属表面化学之间的协同关系对于器件设计和开发的进步至关重要。项目资金还支持来自“危险”学校的高中生参与尖端科学，旨在了解表面化学如何影响金属的电子特性。

The Macromolecular, Supramolecular and Nanochemistry Program of the Division of Chemistry supports Dr. Benjamin Lear from the Pennsylvania State University, University Park. Dr. Lear's project characterizes the interactions between metallic nanoparticles and their surrounding environment. Metallic nanoparticles are extremely small particles of metal where at least one of the structural dimensions (length, width or thickness) is in the nanometer size range (1 to 100 nm). Metallic nanoparticles have a wide range of applications including chemical manufacturing, electronics design, and cancer treatment. In these applications, the environment near the nanoparticle surface can be quite diverse. Little is known about how these changes in environment affect the desirable electronic properties of the nanoparticles. This project develops and applies a new technique to understand the effects of the surrounding environment on the electronic properties of metal nanoparticles. The results of this research will lead to the development of new advanced technologies where the nanoparticle and surrounding environment interactions are optimized. As part of this project, Dr. Lear has multiple high school students working in his lab as part of a Pennsylvania State University outreach program that provides training to students from "at risk" schools.This project examines the influence of surface chemistry and chemical environments on the electronic structure of small (diameters of about 2 nm) gold nanoparticles (AuNPs). A large set of surface chemistries are examined, and the properties of the nanoparticles are studied using x-ray powder diffraction (XRD), transmission electron microscopy (TEM), nuclear magnetic resonance (NMR), electrochemistry, and conduction electron spin resonance (CESR). CESR provides a sensitive and selective probe of the electronic environment experienced by electrons near the Fermi energy within the metallic core. This project establishes the mechanism for the CESR response to changes in surface chemistry. Furthermore, this project explores the sensitivity of AuNPs to changes in their local environment by exploring the effects of changes in solvent, electrochemical potential, and ligands. A detailed understanding of the synergistic relationship between the electronics and surface chemistry of metals are critical for advances in device design and development. The project funding also support the involvement of high school students from "at risk" schools in cutting edge science aimed at understanding how surface chemistry affect electronic properties of metals.