CAREER: Atomic-Scale Visualization of Excitonic States in Individual Carbon Nanotubes

University Of Oregon Eugene, Eugene OR

Investigators

Abstract

In this project funded by the Chemical Measurement and Imaging Program, Professor George Nazin of the University of Oregon will develop new measurement techniques for the visualization of the energy states of individual carbon nanotubes. Carbon nanotubes, or "CNTs" are a form of the element Carbon which have current applications in composite materials, but also have potential for interesting applications in electronics, optoelectronics and bioimaging. Professor Nazin is investigating the electronic and photophysical properties of CNTs. The Nazin group is employing a spatially-resolved spectroscopic technique that allows the team to obtain real-space atomic-resolution electronic maps of individual pristine and chemically-modified CNTs. This work aims to develop a detailed picture of CNT photophysics, which will help guide the principles for rational design of applications based on CNTs. The goal of the project is to establish a quantitative microscopic model of CNT photophysics through direct measurements of spectral structures and spatial behaviors of electronic states corresponding to electronic excitations (excitons) in CNTs. These studies are enabled by a novel scanning tunneling microscope constructed recently by the Nazin group. In this experimental approach, tunneling electrons are used as the excitation source, which allows investigations of CNT photophysics with atomic-scale spatial resolution, currently inaccessible to any other experimental technique. In addition to the direct characterization of excitonic states, spatially-resolved measurements of individual CNTs provide insights into the fundamentally important processes of exciton transport and quenching, the role of defects in these processes, and chemical approaches to controlling these processes. The project is integrated with a middle/high school outreach program developed by Professor Nazin in collaboration with the Springfield, Oregon, school district. The program, designed with teacher input in order to fulfill state science standards, provides year-round engagement of students through hands-on science activities held at the University of Oregon campus.