Show simple item record

dc.contributor.authorWilson, Marken
dc.date2008-09-26 16:23:40.81
dc.date.accessioned2008-09-27T14:37:18Z
dc.date.available2008-09-27T14:37:18Z
dc.date.issued2008-09-27T14:37:18Z
dc.identifier.urihttp://hdl.handle.net/1974/1485
dc.descriptionThesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2008-09-26 16:23:40.81en
dc.description.abstractSingle-walled carbon nanotubes are naturally-forming nanostructures that have attracted considerable recent research interest due to their unique opto-electronic properties and comparative ease of fabrication. Two-thirds of nanotube species are semiconductors due to symmetry conditions imposed by their pseudo-one-dimensional tubular structure, and exhibit band-gap photoluminescence when isolated from their environment. Despite their elegant structural simplicity, fundamental properties of carbon nanotubes, such as their intrinsic quantum efficiency, non-linear excitonic recombination mechanisms, and the role of environmental effects, continue to be disputed in the literature. The design of an apparatus capable of observing nanotube photoluminescence is presented, along with conclusive proof of the observation of a single (9,8)-chirality nanotube in the form of spectral, spatial, and polarization-dependent measurements. The dependance of the excitation and emission spectra of a single nanotube on the excitation intensity is explored and the emission spectra found to be described by a Gaussian peak function, in contrast to previously-reported results. The unexpected ability to cause redshifts in the emission spectrum via the ambient humidity is discovered, which has consequences on experimental best practices. Photoluminescence quantum efficiencies are measured to be 4±2% and 13±6% for two different nanotubes. This is at the high end of the range for comparable literature results, and supports the validity of a recent literature value for the effective atomic absorption coefficient for carbon, AC=1.6×10^−3nm^2, which is ten times greater than previous literature values. Pulsed power dependence studies show that the PL emission undergoes ‘hard’ saturation at an excitation intensity of 0.5×10^12photons/pulse/cm2, which is at least 100 times lower than previous reports and provides insight into non-linear decay dynamics. A novel theoretical model is developed to explain this saturation process, which yields an absorption co-efficient of AC=1.2±0.3×10^−3nm^2 as a fit parameter. Time-resolved photoluminescence dynamics are explored using femtosecond excitation correlation spectroscopy. Results suggest that the one-body decay processes are bi-exponential, with time constants of 31±4ps and 313±61ps, but also highlight the limitations of this technique in observing the expected very rapid (~1 ps) two-body Auger recombination process.en
dc.format.extent3561616 bytes
dc.format.mimetypeapplication/pdf
dc.language.isoengen
dc.relation.ispartofseriesCanadian thesesen
dc.rightsThis publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.en
dc.subjectnanotubeen
dc.subjectcarbonen
dc.subjectphotoluminescenceen
dc.subjectexcitonen
dc.subjectdynamicsen
dc.subjectultrafasten
dc.subjectfemtosecond excitation correlationen
dc.subjectFECen
dc.subjectrelative humidityen
dc.subjectspectroscopyen
dc.subjectsingle-moleculeen
dc.subjectsaturationen
dc.subjectsingle-walleden
dc.subjectfluorescenceen
dc.titleInvestigations into the Optical Properties of Individual, Air-Suspended, Single-Walled Carbon Nanotubesen
dc.typethesisen
dc.description.degreeM.Sc.en
dc.contributor.supervisorFraser, James M.en
dc.contributor.departmentPhysics, Engineering Physics and Astronomyen
dc.degree.grantorQueen's University at Kingstonen


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record