Spectroscopy of Many-Body Effects in Carbon Nanotubes
Final rept. 15 Sep 2006-14 Sep 2009
RICE UNIV HOUSTON TX
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The goal of this research project was to explore the fundamental properties of degenerate one-dimensional 1-D electrons in single-walled carbon nanotubes SWNTs using dynamical methods to probe and understand electronic correlations and many-body phenomena. We studied two aspects of 1-D electron correlations in SWNTs Fermi-edge singularities FES and conduction electron spin resonance ESR. For the FES project, three major strides were taken first, a detailed design of the carbon nanotube field effect transistor structure was made, and a step-by-step procedure was followed for fabrication second, micro-photoluminescence was performed on individual SWNTs in the presence of external electric fields and third, we made the first direct observation of dark excitons in individual SWNTs through low-temperature micro-magneto-photoluminescence spectroscopy. The ESR project has broken new ground on our current understanding of spin resonance in SWNTs. Last year, we discovered that oxygen plays a key role in the electron spin dynamics in nanotubes. Comparing temperature dependent ESR data taken on the same nanotube film in the water-free condition and in the water-free and oxygen-free condition, we were able to perform a detailed lineshape analysis. Several new observations resulted, including an increase in the spin susceptibility when oxygen is removed, Curie-law behavior for the water-free spin susceptibility, linewidth motional narrowing, and saturation of the absorption curve at high microwave powers. In addition, work has begun on producing sample configurations for the single-tube ESR experiment.
- Refractory Fibers
- Atomic and Molecular Physics and Spectroscopy