Estudo da interação elétron-fônon em nanotubos de carbono por Espectroscopia Raman Ressonante

• Ano de defesa: 2009
• Autor(a) principal: Ana Paula Gomes Pereira
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: Espectroscopia Raman; Nanotubos de carbono; Raman, Efeito ressonante; Nanotubos de carbono metálicos; Física
• Link de acesso: http://hdl.handle.net/1843/ESCZ-7YUHM8

In this work, we have used resonance Raman spectroscopy to the study of carbon nanotubes. We reviewed the literature concerning their structural, electronic and vibrational properties, emphasizing the role of many-body effects, particularly the electron-phonon interaction, on the latter two properties. We also reviewed how Raman spectroscopy can be applied to probe these systems, discussing the origin of the various modes in their Raman spectra. Finally, we present experimental results on distinct carbon nanotubes samples, both as-grown and individualized in aqueous dispersion wrapped with surfactants, and isolated on a silicon substrate. We showed, for metallic nanotubes, how the environment around the nanotube can affect both the frequency and the linewidth of the lower frequency component of the so-called G-band, which is believed to be associated with the longitudinal optical (LO) mode. This effect is attributed to a change in the Fermi level of the nanotube, caused by the interaction between the phonons and the conduction electrons in the system. In the case of semiconducting carbon nanotubes, the G-band can be used to probe the degree of aggregation of the nanotubes in a given sample. Raman spectroscopy can, therefore, be used as a probe of how the nanotubes environment can affect their vibrational properties