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

Barnard College, New York NY

Investigators

Abstract

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.