CAREER: Probing Chemistry of Surface-Supported Nanostructures at the Angstrom-Scale

University Of Illinois At Chicago, Chicago IL

Investigators

Abstract

Scanning tunneling microscopy (STM) technology was invented nearly 40 years ago. STM produced the first images of single atoms on a surface. Around the same time, it was discovered that light signals emitted from a vibrating molecule could be amplified more than a million times if the molecule was on the tip of a nanometer-scale metal tip. In this project funded by the Chemical Structure Dynamics and Mechanisms (CSDM-A) program of the Chemistry Division, Professor Nan Jiang of the Department of Chemistry at the University of Illinois at Chicago is developing a state-of-the-art technique that combines scanning tunneling microscopy (STM) with tip-enhanced Raman spectroscopy (TERS) to study bond stretching in an individual molecule with angstrom-scale spatial resolution (an angstrom is one hundred millionths of a centimeter). Using his TERS technique, Professor Jiang and his students study how individual molecules align relative to each other on surfaces. The Jiang research group seeks to uncover the details of how single molecules interact with surfaces. This research may ultimately provide fundamental knowledge that will able the control of surface-supported molecular structures and reactions. As part of this CAREER project, Professor Jiang and his group are bringing the excitement of chemistry research opportunities to community college and local high school students by offering them hands-on research experience in physical chemistry at the single molecule level. Dr. Jiang improves the participation of undergraduate students in experimental chemistry research by establishing a One-Week Physical Chemistry Workshop at UIC. In this workshop, Chicago City Colleges students from diverse backgrounds are exposed to scientific career paths. Dr. Jiang's group provides handheld Raman equipment to community college students in the Chicago area with online training materials and data analysis procedures. This sharing of equipment and data enriches the general chemistry laboratory experience. This project focuses on interrogating the mechanisms of forming and breaking chemical bonds at the angstrom-scale in various chemical environments using novel approaches. The combination of STM imaging with the detailed chemical information provided by Raman spectroscopy allows the interactions between organic adsorbates and specific binding sites on solid surfaces to be probed with spatial and spectroscopic resolution. Furthermore, Raman one-dimensional (1D) line profiles and two-dimensional (2D) mapping achieved with angstrom-scale spatial resolution provide the location of these vibrational modes on the surface, and hence, define the interactions between these molecules and specific binding sites. Detailed mechanistic studies of the elementary steps of surface-supported structure formation are expected to lead to improvements in designing new atom- and energy-efficient materials and molecular assemblies with tailored chemical properties. The students engaged in this research and education project gain valuable experience in both scanning microscopy and optical spectroscopy, as well as quantum mechanics theory calculations which aid in the interpretation of experimental data. 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.