The Vibrational Structure of Atomically-Precise Nanostructures: From Molecular Clusters to Quantum Dots

在这个由化学系大分子、超分子和纳米化学项目支持的合作项目中，巴纳德学院的安德鲁·克劳瑟教授、哥伦比亚大学的乔纳森·欧文教授和他们的本科生研究团队正在开发对原子精确量子点纳米结构的振动结构的理解。分子和材料中原子的振动是原子运动的一种基本形式，与化学键的伸展和收缩有关。通过了解分子振动以及这些运动如何影响结构和几何形状，科学家可以改善材料和设备的性能。本文主要研究了硒化镉和硫化镉量子点的设计、合成和表征。这些材料在许多消费品中用作光阻剂，如相机测光表，时钟收音机，报警设备和太阳能路灯。与巴纳德学院（Barnard College）、高等教育机会项目（Higher Education Opportunity Program）和大学科技入门项目（Collegiate Science and Technology Entry Program）合作，让低收入和代表性不足的大学生和K-12学生参与研究。每年夏天，都会有一名未被充分代表的学生跟随一名正在研究这个项目的学生，加入实验室进行他们自己的研究。这项研究也被纳入巴纳德学院新的年度“纳米日”，让当地高需求学校的学生和教师接触纳米科学和材料化学。在这个项目中，拉曼光谱被用来确定一个不同的振动结构，但相关的一组原子精确的簇和量子点。配体和金属阳离子交换反应探讨了表面化学如何影响一系列精确尺寸和形状的硒化镉和硫化镉量子点的振动结构。具有单分散尺寸和界面原子分布的核壳量子点可以研究核、壳和界面的振动结构。最后，分子团簇连接形成二聚体，三聚体，最终形成长聚合物链，以确定振动结构如何从零维到一维极限变化。每年夏天，都会有一名未被充分代表的学生跟随一名正在研究这个项目的学生，随后加入实验室进行他们自己的研究。这项研究也被纳入巴纳德学院新的年度“纳米日”，让当地高需求学校的学生和教师在微观层面上研究物理和化学系统，纳米科学，以及它们的材料特性。这些都是新科技发展的关键领域，将为美国未来的创新提供动力。

In this collaborative project, supported by the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry, Professor Andrew Crowther of Barnard College, Professor Jonathan Owen of Columbia University, and a team of their undergraduate research students are developing an understanding of the vibrational structure of atomically precise quantum dot nanostructures. The vibrations of atoms in molecules and materials are a fundamental type of atomic motion related to the stretching and contracting of chemical bonds. By understanding molecular vibrations and how these motions impact structure and geometry, scientists can improve the performance of materials and the devices. This research is focused on the design, synthesis and characterization of quantum dots of cadmium selenide and cadmium sulfide. These materials are used as photoresists in many consumer items such as camera light meters, clock radios, alarm devices, and solar street lights. Partnerships with programs at Barnard College, the Higher Education Opportunity Program and Collegiate Science and Technology Entry Program, to involve low-income and underrepresented college and K-12 students to research. Each summer an underrepresented student shadows a current research student on this project, joining the laboratory to conduct their own research. This research is also incorporated into a new, annual "NanoDay" at Barnard College that exposes students and teachers from local high-need schools to nanoscience and materials chemistry. In this project Raman spectroscopy is used to determine the vibrational structure of a diverse, yet related set of atomically precise clusters and quantum dots. Ligand and metal cation exchange reactions probe how surface chemistry affects the vibrational structure of a series of qadmium selenide and cadmium sulfide quantum dots of precise size and shape. Core-shell quantum dots with monodispersity in size and interfacial atomic distributions enable investigations of the core, shell, and interfacial vibrational structure. Finally, molecular clusters are linked to form dimers, trimers, and ultimately long polymer chains to determine how the vibrational structure changes from the zero-dimensional to the one-dimensional limit. Each summer an underrepresented student shadows a current research student on this project and subsequently joins the laboratory to conduct their own research. This research is also incorporated into a new, annual "NanoDay" at Barnard College that exposes students and teachers from local high-need schools to the study of physical and chemical systems at the microscopic level, nanoscience, as well as their material properties. These are key areas in the development of new science and technology, which will power American innovation in the future.