Raman spectroscopy of single wall carbon nanotubes

Abstract

A single wall carbon nanotube (SWNT) is a new form of carbon, whose atomic arrangement is equivalent to a graphene sheet rolled into a cylinder in a seamless way. The typical diameter of a SWNT ranges from 0.6 nm to several nm and the typical length ranges from tens of nm to several cm. Due to its small diameter and high aspect ratio, a SWNT has very unique electronic and vibrational properties. The goals of this thesis work are to design and construct a Raman instrument capable of obtaining signals from many different types of individual SWNTs, to develop methods and tools to collect, organize and analyze large amounts of Raman spectra from them, to use resonant Raman spectroscopy to characterize individual SWNTs, and to investigate how their electronic and vibrational properties change under various conditions, such as strain, or different substrate interactions. A high-efficiency widely-tunable Raman instrument is developed for the study of SWNTs. The environmental effects on the electronic and vibrational properties are investigated by suspended SWNTs. Using the high-efficiency Raman instrument, weak optical transitions of metallic SWNTs are found. The effect of strain on the vibrational mode frequencies of SWNTs are studied.