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dc.contributor.advisor Tittel, Frank K.
dc.creatorHaroz, Erik
dc.date.accessioned 2013-09-16T15:12:39Z
dc.date.accessioned 2013-09-16T15:12:42Z
dc.date.available 2013-09-16T15:12:39Z
dc.date.available 2013-09-16T15:12:42Z
dc.date.created 2013-05
dc.date.issued 2013-09-16
dc.date.submitted May 2013
dc.identifier.urihttps://hdl.handle.net/1911/71962
dc.description.abstract The armchair variety of single-wall carbon nanotubes (SWCNTs) is the only nanotube species that behaves as a metal with no electronic band gap and massless carriers, making them ideally suited to probe fundamental questions of many-body physics of one-dimensional conductors as well as to serve in applications such as high-current power transmission cables. However, current methods of nanotube synthesis produce bulk material comprising of a mixture of nanotube lengths, diameters, wrapping angles, and electronic types due to the inability to control the growth process at the nanometer level. As a result, measurements of as-grown SWCNTs produce a superposition of electrical and optical responses from multiple SWCNT species. This thesis demonstrates production of aqueous suspensions composed almost entirely of armchair SWCNTs using a post-synthesis separation method employing density gradient ultracentrifugation (DGU) to separate different SWCNT types based on their mass density and surfactant-specific interactions. Resonant Raman spectroscopy determines the relative abundances of each nanotube species, before and after DGU, by measuring the integrated intensity of the radial breathing mode, the diameter-dependent radial vibration of the SWCNT perpendicular to its main axis, and quantifies the degree of enrichment of bulk nanotube samples to exclusively armchair tubes. Raman spectroscopy of armchair-enriched samples of the G-band mode, which is composed of longitudinal (G-) and circumferential (G+) vibrations oscillating parallel and perpendicular to the tube axis, shows that the G- peak, long-held to be an indicator for the presence of metallic SWCNTs, appears only when electronic resonance with narrow-gap semiconducting SWCNTs occurs and shows only the G+ component in spectra containing only armchair species. Finally, by combining optical absorption measurements with nanotube composition as determined earlier via Raman scattering, peak fitting of absorption spectra indicates that interband transitions of armchair SWCNTs are strongly excitonic as shown by the highly symmetric peak lineshapes, a property normally attributed to semiconductors. Such lineshapes allow classification of armchair SWCNTs as a unique hybrid class of optical nanomaterial. Combining absorption and Raman scattering measurements establishes a distinct optical signature that describes the fundamental optical processes within armchair SWCNTs and lays the foundation for future studies of many-body photophysics and electrical applications.
dc.format.mimetype application/pdf
dc.language.iso eng
dc.subjectCarbon nanotubes
Photophysics
Separation
Absorption
Resonant Raman scattering
Armchair
dc.title Enrichment and Fundamental Optical Processes of Armchair Carbon Nanotubes
dc.contributor.committeeMember Xu, Qianfan
dc.contributor.committeeMember Hauge, Robert H.
dc.date.updated 2013-09-16T15:12:42Z
dc.identifier.slug 123456789/ETD-2013-05-486
dc.type.genre Thesis
dc.type.material Text
thesis.degree.department Electrical and Computer Engineering
thesis.degree.discipline Engineering
thesis.degree.grantor Rice University
thesis.degree.level Doctoral
thesis.degree.name Doctor of Philosophy
dc.identifier.citation Haroz, Erik. "Enrichment and Fundamental Optical Processes of Armchair Carbon Nanotubes." (2013) Diss., Rice University. https://hdl.handle.net/1911/71962.


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