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The Optical Properties Of Single Walled Carbon Nanotubes Separation Characterization And Measurement In Suspension
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Book Synopsis The Optical Properties of Single-walled Carbon Nanotubes: Separation, Characterization, and Measurement in Suspension by : Richard M. Russo
Download or read book The Optical Properties of Single-walled Carbon Nanotubes: Separation, Characterization, and Measurement in Suspension written by Richard M. Russo and published by . This book was released on 2006 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: The one dimensional structure of single-walled carbon nanotubes (SWNTs) gives rise to optical phenomena that differ from bulk materials. This dissertation studies the separation of SWNTs dissolved in aqueous media using surfactant molecules, and the measurement of their intrinsic optical properties including absorption and emission. The SWNTs were separated from the bundled form using mechanical processing techniques such as sonication and centrifugation. A processing study, which isolated the effects of sonication frequency, sonication power, and centrifugation speed, was performed to determine the factors that lead to the best separation. The results of this study suggest that the suspensions are a mixture of individual tubes and small bundles. Prior determinations of intrinsic nanotube properties based on the assumption of isolated nanotubes will have to be revisited. The transient absorption spectrum was measured for the S11 subband region using monochromatic pump excitation at wavelengths corresponding to S22 subband transitions, where the exciting pump fluence was sufficient to create many excitons on a single nanotube. The transient decay kinetics followed a linear dependence that was proportional to 1/ t on a log-log scale with a slope of -0.5, which is consistent with the diffusion limited recombination of excitons in one dimension. This result suggests that the decay of photoexcitations in nanotubes is initially governed by two-body kinetics, which becomes a one-body process only in the long time limit. Our work refutes the one-electron model for the excited state relaxation of nanotubes proposed by others. When the transient decay was studied as a function of the initial exciton population, the diffusion coefficient was found to be a different constant value at each initial population. Local thermalization of the surrounding medium may cause this difference, as thermal relaxation occurs on a time scale that is longer than that of exciton recombination in SWNTs. This work further elucidates the mechanism of excited state relaxation in SWNTs, and advances the understanding of one-dimensional nanostructures.
Book Synopsis Separation of Single Walled Carbon Nanotubes with Different Methods by : Yusheng Chen
Download or read book Separation of Single Walled Carbon Nanotubes with Different Methods written by Yusheng Chen and published by . This book was released on 2013 with total page 151 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since their discovery, single walled carbon nanotubes (SWNTs) have attracted much attention due to their superior mechanical and electronic properties that have led to their use in various applications. The electronic structure and optical properties of individual SWNT are uniquely dependent on the tube's chirality and diameter. In the as-prepared sample, tubes are generally produced as a complex mixture containing many different chiral species. Selective enrichment and separation of SWNTs will play a vital role in the realization of the potential application of SWNTs. Separation of different types of SWNTs, however, remains one of the fundamental and challenging issues in nano science. In this dissertation, several approaches have been examined to separate SWNTs, which are based on different molecular interaction with nanotubes, nanotube aggregation and chromatography. Among the polymers examined are water soluble poly[(mphenylenevinylene)-alt-(p-phenylenevinylene)] (PmPV), poly[(phenyleneethynylene)-copoly(phenylenevinylene)] (PPE-PPV), and water soluble poly[(m-phenyleneethynylene)-alt-(p-phenyleneethynylene)] (PPE). Arising from the bent angle from m-phenylene, these polymers can form helical conformation to facilitate an intimate interaction between polymer chains and SWNTs. With unsymmetrical side groups, water soluble PmPV demonstrates that the polymer helical conformation can be controlled to sort the SWNTs by their diameters. Introduction of rotatable phenylenethynylene (PE) on the backbone allows polymer PPE-PPV quickly adjust the conformation for interaction with the SWNTs of a suitable diameter, which leads to the large diameter selectivity. The study of water soluble PPE polymer also reveals the intriguing selectivity toward tube (6,5), illustrating the impact of the carbon-carbon triple bonds on the SWNT selectivity. The nanotubes from SWNTs/polymers dispersion tends to form aggregation. Analysis of the aggregate SWNTs shows that the sample contains enriched semiconducting SWNTs. In addition, the SWNTs are found to form aligned bundles. Polyethylenimine (PEI) is found to exhibit selective interaction with semiconducting SWNTs. By using this property, a PEI/cellulose column chromatography can be used to separate a blue solution from the raw HiPCO SWNTs. Analysis by Raman, 2D fluorescence and UV-vis-NIR absorption spectra suggests that the isolated blue solution is pure metallic SWNTs. By changing eluent, this PEI/cellulose column chromatography appears to be capable of separating different SWNT species with single chirality. Cationic surfactant, like benzyltrimethylammonium chloride also shows an affinity towards semiconducting SWNTs, in contrast to the little selectivity of anionic surfactant.
Book Synopsis The Optical Properties of Single-walled Carbon Nanotubes by : Hermenegildo Nuno Pedrosa
Download or read book The Optical Properties of Single-walled Carbon Nanotubes written by Hermenegildo Nuno Pedrosa and published by . This book was released on 2006 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Optical Properties of Single Walled Carbon Nanotubes by : HUALING. ZENG
Download or read book Optical Properties of Single Walled Carbon Nanotubes written by HUALING. ZENG and published by . This book was released on 2017-01-27 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Single-Walled Carbon Nanotubes by : Yan Li
Download or read book Single-Walled Carbon Nanotubes written by Yan Li and published by Springer. This book was released on 2019-05-16 with total page 333 pages. Available in PDF, EPUB and Kindle. Book excerpt: The series Topics in Current Chemistry Collections presents critical reviews from the journal Topics in Current Chemistry organized in topical volumes. The scope of coverage is all areas of chemical science including the interfaces with related disciplines such as biology, medicine and materials science. The goal of each thematic volume is to give the non-specialist reader, whether in academia or industry, a comprehensive insight into an area where new research is emerging which is of interest to a larger scientific audience. Each review within the volume critically surveys one aspect of that topic and places it within the context of the volume as a whole. The most significant developments of the last 5 to 10 years are presented using selected examples to illustrate the principles discussed. The coverage is not intended to be an exhaustive summary of the field or include large quantities of data, but should rather be conceptual, concentrating on the methodological thinking that will allow the non-specialist reader to understand the information presented. Contributions also offer an outlook on potential future developments in the field.
Book Synopsis Optical Properties of Single-walled Carbon Nanotubes by : Ian Brooke Mortimer
Download or read book Optical Properties of Single-walled Carbon Nanotubes written by Ian Brooke Mortimer and published by . This book was released on 2007 with total page 374 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Dispersion of Narrow Diameter Carbon Nanotubes for Optical Characterization by : Hemant M. Shah
Download or read book Dispersion of Narrow Diameter Carbon Nanotubes for Optical Characterization written by Hemant M. Shah and published by . This book was released on 2008 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt: Optical properties of carbon nanotubes have recently attracted considerable amount of attention. Due to there direct band gap material characteristic these and dimension of the order of nano meters they find potential applications in the field of nano photonics. Thus the optical study of carbon nanotubes is important for both fundamental research and for the next generation technical applications. In this thesis single walled carbon nanotubes were dispersed in various encapsulates such as surfactants, polymers, proteins etc to separate them individually and study there optical properties. The individually dispersed single walled carbon nanotubes displayed unique absorbance spectra. The optical absorption spectrum of a particular tube is expected to be dominated by a series of relatively sharp inter-band transitions, at energies associated with the van Hove singularities, the absorbance spectrum obtained on our samples were consistent with this expectation. Our samples also showed sharp photoluminescence peaks mostly from the semiconducting single walled carbon nanotubes. The detailed overlap of the absorbance spectra and photoluminescence spectra lead us to believe that our samples contain mainly individual tubes encapsulated in one of the surfactants or polymers. Thin film transistors (TFT) were made with a mesh of single walled carbon nanotubes as the active channel on top of a silicon/silicon oxide substrate, with silicon acting as a back gate and titanium/gold electrodes were evaporated on top of the nanotube film. Photocurrent properties of these thin films were investigated and they showed a huge change in the photocurrent in the presence and absence of the laser light. Thin films of carbon nanotubes were also deposited on rectangular silicon substrates and the influence of applied strain in the presence of laser light was investigated. These films showed a huge change in resistance on application of mechanical strain. Raman measurements were also performed on these thin films and the obtained radial breathing mode (RBM) data helped resolve the diameter of many single walled carbon nanotubes.
Book Synopsis Investigations Into the Optical Properties of Individual, Air-suspended, Single-walled Carbon Nanotubes by : Mark William Brennan Wilson
Download or read book Investigations Into the Optical Properties of Individual, Air-suspended, Single-walled Carbon Nanotubes written by Mark William Brennan Wilson and published by . This book was released on 2008 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt: Single-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 x 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 x 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 x 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.
Book Synopsis Optical Properties of Single Walled Carbon Nanotubes by : Hualing Zeng
Download or read book Optical Properties of Single Walled Carbon Nanotubes written by Hualing Zeng and published by . This book was released on 2008 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Handbook Of Carbon Nanomaterials (Volumes 9-10) by : R Bruce Weisman
Download or read book Handbook Of Carbon Nanomaterials (Volumes 9-10) written by R Bruce Weisman and published by World Scientific. This book was released on 2019-01-22 with total page 812 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume is a tribute to the career of Prof. Mildred Dresselhaus. It focuses on the optical properties and spectroscopy of single-wall carbon nanotubes. It contains chapters on diverse experimental and theoretical aspects of the field, written by internationally recognized experts. The volume serves as an important resource for researchers and students interested in carbon nanotubes.
Book Synopsis Carbon nanotubes and graphene for photonic applications by : K. Matsuda
Download or read book Carbon nanotubes and graphene for photonic applications written by K. Matsuda and published by Elsevier Inc. Chapters. This book was released on 2013-08-31 with total page 31 pages. Available in PDF, EPUB and Kindle. Book excerpt: The fundamental electronic states and optical properties of single-walled carbon nanotubes are briefly explained in this chapter. Moreover, the novel optical properties of carbon nanotubes revealed by advanced laser spectroscopy (single-nanotube spectroscopy and time-resolved spectroscopy) are introduced. Due to the enhanced Coulomb interaction, the optically generated electron-hole pair forms a strongly bound ‘exciton’ state, analogous to the hydrogen-like state in the carbon nanotubes. The striking features of excitons in the carbon nanotube, such as singlet-dark states and triplet states, which dominate the optical properties, are described in this chapter.
Book Synopsis Ultrafast Dynamics of Individual Air-suspended Single-walled Carbon Nanotube by : Tam Q. Nhan
Download or read book Ultrafast Dynamics of Individual Air-suspended Single-walled Carbon Nanotube written by Tam Q. Nhan and published by . This book was released on 2008 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thorough understanding of the electronic and optical properties of single-walled carbon nanotubes (SWCNTs) will no doubt benefit future technological applications. Since the discovery of band gap photoluminescence from isolated semiconducting SWCNTs, significant progresses in studying the optical properties of SWCNTs have been made (e.g. linear polarization along the tube axis for the absorption and emission of light, excitonic nature in SWCNT excitation). However, there are still several controversial parameters of SWCNTs (e.g. quantum efficiency, absorption cross section, radiative lifetime, and Auger recombination lifetime). With the advancement in SWCNT sample preparation, studies of SWCNT intrinsic properties have shifted from ensemble to a single tube level, in which the ambiguities in elucidating intrinsic properties posed by the assortment of different tube species can be minimized. By examining individual SWCNTs suspended in air, in contrast to micelle-encapsulated SWCNTs, we believe that the environmental effects can be reduced. This thesis will demonstrate the capability of doing spectroscopy on a single semiconducting air-suspended SWCNT. In continuous-wave excitation, the photoluminescence excitation map and high resolution photoluminescence (PL) image of a SWCNT can be constructed, and PL polarization is proven. Quantum efficiency of 5% is experimentally estimated for (9,8) and (10,8) chiral SWCNTs. Pulse excitation allows us to study the intrinsic exciton dynamics of a SWCNT. To gain insight into exciton nonlinear decay processes, PL saturation in pump power dependence measurement is investigated and compared to the simulated results from stochastic models of exciton dynamics. Femtosecond excitation correlation spectroscopy with 150 fs time resolution is employed to time-resolve the PL of a single tube suspended in air.
Book Synopsis Effects of Chemical Environment on the Optical Properties of Single-walled Carbon Nanotubes by : Wei-Chun Hung
Download or read book Effects of Chemical Environment on the Optical Properties of Single-walled Carbon Nanotubes written by Wei-Chun Hung and published by . This book was released on 2011 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt: Next, the dispersion of SWNTs in Nafion aqueous system is sustainable in ethanol and in salt solutions for observing well-resolved NIR fluorescence peaks of SWNTs. The optical property of the SWNT/Nafion suspension is studied by means of reversible oxidative quenching behavior with different oxidants including H2 O2 and I2 . Additionally, a simple and rapid one-step method for encapsulating SWNT/Nafion suspension into silica for fluorescence studies is also described. The redox reactions of fluorescent SWNT/silica composite with H2 O2 and I2 , either in water or in air, are studied with respect to time. Under this condition, the fluorescence of SWNT/silica composite shows the exponential decay and the dependence on the thickness of the silica composite.
Book Synopsis Quantitative Optical Imaging of Single-walled Carbon Nanotubes by : Lihong Huang Herman
Download or read book Quantitative Optical Imaging of Single-walled Carbon Nanotubes written by Lihong Huang Herman and published by . This book was released on 2013 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: The development and application of optical imaging tools and probing techniques have been the subject of exciting research. These tools and techniques allow for non-invasive, simple sample preparation and relatively fast measurement of electronic and optical properties. They also provided crucial information on optoelectronic device application and development. As the field of nanostructure research emerged, they were modified and employed to understand various properties of these structures at the diffraction limit of light. Carbon nanotubes, up to hundreds of micrometers long and several nanometers thin, are perfect for testing and demonstrating newly-developed optical measurement platforms for individual nanostructures, due to their heterogeneous nature. By employing two quantitative imaging techniques, wide-field on-chip Rayleigh scattering spectroscopy and spatial modulation confocal absorption microscopy, we investigate the optical properties of single-walled carbon nanotubes. These techniques allow us to obtain the Rayleigh scattering intensity, absolute absorption cross section, spatial resolution, and spectral information of single-walled carbon nanotubes. By probing the optical resonance of hundreds of single-walled carbon nanotubes in a single measurement, the first technique utilizes Rayleigh scattering mechanism to obtain the chirality of carbon nanotubes. The second technique, by using high numerical aperture oil immersion objective lenses, we measure the absolute absorption cross section of a singlewalled carbon nanotube. Combining all the quantitative values obtained from these techniques, we observe various interesting and recently discovered physical behaviors, such as long range optical coupling and universal optical conductivity on resonance, and demonstrate the possibility of accurate quantitative absorption measurement for individual structures at nanometer scale.
Book Synopsis Carbon Nanotubes by : Stephanie Reich
Download or read book Carbon Nanotubes written by Stephanie Reich and published by John Wiley & Sons. This book was released on 2008-09-26 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon nanotubes are exceptionally interesting from a fundamental research point of view. Many concepts of one-dimensional physics have been verified experimentally such as electron and phonon confinement or the one-dimensional singularities in the density of states; other 1D signatures are still under debate, such as Luttinger-liquid behavior. Carbon nanotubes are chemically stable, mechanically very strong, and conduct electricity. For this reason, they open up new perspectives for various applications, such as nano-transistors in circuits, field-emission displays, artificial muscles, or added reinforcements in alloys. This text is an introduction to the physical concepts needed for investigating carbon nanotubes and other one-dimensional solid-state systems. Written for a wide scientific readership, each chapter consists of an instructive approach to the topic and sustainable ideas for solutions. The former is generally comprehensible for physicists and chemists, while the latter enable the reader to work towards the state of the art in that area. The book gives for the first time a combined theoretical and experimental description of topics like luminescence of carbon nanotubes, Raman scattering, or transport measurements. The theoretical concepts discussed range from the tight-binding approximation, which can be followed by pencil and paper, to first-principles simulations. We emphasize a comprehensive theoretical and experimental understanding of carbon nanotubes including - general concepts for one-dimensional systems - an introduction to the symmetry of nanotubes - textbook models of nanotubes as narrow cylinders - a combination of ab-initio calculations and experiments - luminescence excitation spectroscopy linked to Raman spectroscopy - an introduction to the 1D-transport properties of nanotubes - effects of bundling on the electronic and vibrational properties and - resonance Raman scattering in nanotubes.
Book Synopsis Springer Handbook of Nanomaterials by : Robert Vajtai
Download or read book Springer Handbook of Nanomaterials written by Robert Vajtai and published by Springer Science & Business Media. This book was released on 2013-08-20 with total page 1234 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Springer Handbook of Nanomaterials covers the description of materials which have dimension on the "nanoscale". The description of the nanomaterials in this Handbook follows the thorough but concise explanation of the synergy of structure, properties, processing and applications of the given material. The Handbook mainly describes materials in their solid phase; exceptions might be e.g. small sized liquid aerosols or gas bubbles in liquids. The materials are organized by their dimensionality. Zero dimensional structures collect clusters, nanoparticles and quantum dots, one dimensional are nanowires and nanotubes, while two dimensional are represented by thin films and surfaces. The chapters in these larger topics are written on a specific materials and dimensionality combination, e.g. ceramic nanowires. Chapters are authored by well-established and well-known scientists of the particular field. They have measurable part of publications and an important role in establishing new knowledge of the particular field.
Book Synopsis Optical Properties of Doped Semiconducting Single-Walled Carbon Nanotubes by :
Download or read book Optical Properties of Doped Semiconducting Single-Walled Carbon Nanotubes written by and published by . This book was released on 2009 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:
