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Investigation Of Doping And Photoexcitation In Carbon Nanotubes Using Raman Spectroscopy
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Book Synopsis Investigation of Doping and Photoexcitation in Carbon Nanotubes Using Raman Spectroscopy by : Abdul Waheed Anwar
Download or read book Investigation of Doping and Photoexcitation in Carbon Nanotubes Using Raman Spectroscopy written by Abdul Waheed Anwar and published by . This book was released on 2011 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt: Raman spectroscopy is a non-invasive characterization technique suitable for the study of carbon nanotubes. Differences in the spectral shift of the Raman D and G bands are observed when heating carbon nanotubes through intense photon irradiation and by varying the temperature in a thermostat. These spectral changes in D mode are attributed to the variation of the electronic band structure by excitons creation. The investigation of the influence of doping and photoexcitation on the Raman G and D band of carbon nanotubes show that Raman spectroscopy can be used as a diagnostic tool. The spectral bands broaden and up shifts for nitrogen doped multi walled carbon nanotubes (MWCNT). The up shift for sulphuric acid doped double wall carbon nanotubes (DWCNT) synthesized from catalytic chemical vapor deposition method (CCVD) is attributed to charge transfer and strain in the lattice. We have combined sulphuric acid doping and high pressure Raman spectroscopy to investigate the properties of DWCNT. The DWCNT doped with different concentrations of sulphuric acid are explored under high pressure suggesting an effect of the molecular ordering around carbon nanotubes at higher acid concentrations. Raman spectra of individual double wall carbon nanotubes on silica show a splitting of the G band due to contributions of the inner and outer tube when using a excitation energy in resonance with the inner metallic tube and outer semiconducting tube. The spectral line widths are comparable to what has been observed for individual single wall carbon nanotubes (SWCNT) or graphene. Increased laser power shifts the G band of the outer tube to higher energies and modifies its line shape.
Book Synopsis Evaluations of Single Walled Carbon Nanotubes Using Resonance Raman Spectroscopy by : Victor Watson Brar
Download or read book Evaluations of Single Walled Carbon Nanotubes Using Resonance Raman Spectroscopy written by Victor Watson Brar and published by . This book was released on 2004 with total page 81 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work reports the results of two studies which use resonance Raman scattering to evaluate the vibrational properties of single walled carbon nanotubes (SWNTs). In the first study, we report an evaluation of second-order combination and over-tone modes in highly ordered pyrolytic graphite (HOPG), in SWNT bundles, and in isolated SWNTs. We found both dispersive and non-dispersive Raman bands in the range 1650-2100 cm−1, and we show that the appearance and frequency vs. laser energy E[laser] behavior of these features are in agreement with predictions from double resonance Raman theory. In the case of SWNTs, these second-order bands depend on the one-dimensional structure of SWNTs, and, at the single nanotube level, the spectra vary from tube to tube, depending on tube diameter and chirality, and on the energy of the van Hove singularity relative to E[laser]. In the second study, we present a theoretical method of predicting, to within a linear constant [beta], the frequency shift in the Raman features of a SWNT material as the Fermi level is changed by depletion or addition of electrons. This constant is then evaluated for different Raman modes in SWNTs by comparing theoretical predictions to experimental observations by Corio et al., where the Fermi level of SWNT bundles is raised by electrochemical doping and Raman spectra are collected in situ. It is determined that for the G-band of SWNTs, the dependence of frequency on Fermi energy is /[beta][sub]G = 271cm−1 per hole per C-atom for metallic SWNTs with d[sub]f [approximately]= 1.25 ± 0.20nm.
Book Synopsis Nanotube Superfiber Materials by : Noe T. Alvarez
Download or read book Nanotube Superfiber Materials written by Noe T. Alvarez and published by Elsevier Inc. Chapters. This book was released on 2013-09-16 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon nanotubes (CNTs) have been at the frontier of nanotechnology research for the past two decades. The interest in CNTs is due to their unique physical and chemical properties, which surpass those of most other materials. To put CNTs into macroscale applications, the nanotubes can be spun to form continuous fiber materials. Thus far, the properties of the fibers are far below the properties of the individual nanotubes. If the electrical and mechanical properties of the fibers could be improved, the resulting superfiber materials would change the industry and society. For example, CNT materials might replace copper wires providing lighter, stronger cables for aerospace applications. The small size of individual nanotubes, and the mixture of different diameters and chiralities, limits the electrical conductivity of CNT fiber. A simple way to improve the electrical conductivity of CNT fibers is chemically doping the CNTs within the fibers. This chapter attempts to summarize, classify and provide a basic understanding of doping at the atomic and molecular levels. Characterization of doping and current results of our doping efforts are discussed.
Book Synopsis Doping of Carbon Nanotubes by : Sergey Bulyarskiy
Download or read book Doping of Carbon Nanotubes written by Sergey Bulyarskiy and published by Springer. This book was released on 2017-07-01 with total page 197 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book addresses the control of electronic properties of carbon nanotubes. It presents thermodynamic calculations of the formation of impurities and defects in the interaction of nanotubes with hydrogen, oxygen, nitrogen and boron, based on theoretical models of the formation of defects in carbon nanotubes. It is shown that doping and adsorption lead to changes in the electronic structure of the tubes as well as to the appearance of impurity states in the HOMO-LUMO gap. The book presents examples of specific calculations for doping of carbon nanotubes with oxygen, hydrogen, nitrogen and boron, together with numerous experimental results and a comparison with the author’s thermodynamic calculations. Possible directions of the technological processes of optimization are pointed out, as well as the perspectives of p-n-transition creation with the help of carbon nanotube arrays. The results presented were derived from the physics of the processes and a theoretical model of the technological processes. Though a wealth of empirical information on doping nanotubes has been accumulated in the scientific literature, what is lacking is a theoretical model for their analysis. As such, the book develops a thermodynamic model of the self-organization of structural elements in multicomponent systems – including carbon nanotubes, clusters and precipitates in condensed matter – and subsequently adapts it to the doping of carbon nanotubes. This approach allows readers to gain a far deeper understanding of the processes of doping carbon nanotubes.
Book Synopsis A Solid-state Doping Technology for Carbon Nanotubes by : Luckshitha Suriyasena Liyanage
Download or read book A Solid-state Doping Technology for Carbon Nanotubes written by Luckshitha Suriyasena Liyanage and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Single wall carbon nanotubes (SWCNTs) have great potential of becoming the channel material for future high-speed transistor technology. Despite tremendous progress in the recent years, certain challenges still remain to be addressed to realize a scaled CNT based transistor technology. In this thesis I address three fundamental challenges that are essential to realizing a SWCNT-based transistor technology. One of the fundamental issues in carbon nanotube transistor technology originates from material synthesis which provides us a mixture of metallic and semiconducting CNTs. To use the semiconducting CNT as the transistor channel material, we developed a solution-based carbon nanotube sorting process where semiconducting CNTs can be sorted from metallic CNTs to a> 99% of purity. The main application of CNTs following this sorting process is for thin film transistors (TFTs) that can be utilized on flexible transparent substrates. In order to achieve carbon nanotube field effect transistors (CNTFETs) with excellent gate control, it is essential to understand the interactions between CNTs and gate insulation materials - ALD high-k dielectrics. In the second section I will investigate the effects of atomic layer deposited (ALD) high-k dielectrics (Al2O3 & HfO2) on SWCNTs. We study the ALD nucleation and growth on SWCNTs and we confirm our findings and gain insightful information using Raman Spectroscopy. In the third part of the thesis I present a novel, VLSI-compatible solid-state doping technique to fabricate n-type carbon nanotube transistors using low work-function metal oxides as gate dielectrics. Using this technique we demonstrate wafer-scale, aligned CNT transistors with yttrium oxide (Y2Ox) gate dielectrics that exhibit excellent n-type behavior. We confirm this mechanism by carrying out a variety of characterization techniques and provide a general guideline for CNT doping that could also be applicable for MoS2 and graphene. This thesis paves the way to exploiting a wide range of materials for an effective n-type carbon nanotube transistor for a complementary (p- and n-type) transistor technology.
Book Synopsis Spectroscopic Studies of Doping and Charge Transfer in Single Walled Carbon Nanotubes and Lead Sulfide Quantum Dots by : Neale O. Haugen
Download or read book Spectroscopic Studies of Doping and Charge Transfer in Single Walled Carbon Nanotubes and Lead Sulfide Quantum Dots written by Neale O. Haugen and published by . This book was released on 2015 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt: The use of single wall carbon nanotubes (SW-CNTs) in solar photovoltaic (PV) devices is a relatively new, but quickly growing field. SW-CNTs have found application as transparent front contacts, and high work function back contacts in thin film solar PV. For the utility of SW-CNTs to be fully realized, however, controllable and stable doping as well as long term protection from doping must be achieved. Spectroscopic techniques facilitate detailed investigations of the intrinsic and variable properties of semiconductor materials without the issues of contact deposition and the possibility of sample contamination. Detailed spectroscopic analysis of the doping induced changes in the optical properties of SW-CNTs has revealed normally hidden excited state transitions in large diameter single walled carbon nanotubes for the first time. Spectroscopic monitoring of the degree of doping in SW-CNTs made possible studies of the dopant complex desorption and readsorption energies and kinetics. The long term protection from doping of SW-CNTs exposed to ambient laboratory conditions was achieved as a result of the more detailed understanding of the doping processes and mechanisms yielded by these spectroscopic studies. The application of SW-CNTs to other roles in solar PV devices was another goal of this research. Efficient collection of photogenerated charge carriers in semiconductor quantum dot (QD) based solar photovoltaic devices has been limited primarily by the poor transport properties and high density of recombination sites in the QD films. Coupling semiconductor QDs to nanomaterials with better transport properties is one potential solution to the poor transport within the QD films. This portion of the work investigated the possibility of charge transfer occurring in nano-heterostructures (NHSs) of PbS QDs and SW-CNTs produced through spontaneous self-assembly in solution. Electronic coupling in the form of charge transfer from the QDs to the SW-CNTs is unambiguously confirmed by the dependence of the Raman G-band shift on the QD size, and thus upon the QD bandgap. Charge transfer is further corroborated by similar size dependence in the efficiency of the SW-CNTs as quenchers of the QD photoluminescence (PL). NHSs thus produced could be used in QD based solar cells to improve the overall device efficiency by improving exciton dissociation, charge transport, and charge collection.
Book Synopsis The Use of Raman Spectroscopy to Study Carbon Nanotubes by : Mahdi Mohammed
Download or read book The Use of Raman Spectroscopy to Study Carbon Nanotubes written by Mahdi Mohammed and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Harnessing the Properties of Carbon Nanotubes to Increase Applicability by : Christopher Rotella
Download or read book Harnessing the Properties of Carbon Nanotubes to Increase Applicability written by Christopher Rotella and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon nanotubes have been an interest in the field of materials research since their identification in 1991. They boast robust mechanical, electrical, thermal, and chemical properties that make them desirable for a wide range of applications. A main feature that is studied heavily in this work is their acceptance of many different chemical dopants. Dopants such as B, N, Si, and S have been utilized in previous works, all showing unique changes to the physical properties of CNTs, allowing them to be tailored to different applications. This thesis seeks to further increase the applicability of CNTs through various methods, for both broad and specific applications.Nitrogen and silicon doping and their affect on both single- and multi-walled carbon nanotubes is studied in the effort of controlling their growth parameters. By introducing a growth aid in the form of ethanol, heights of vertically aligned N-doped multi-walled tubes were extended over 200% from heights with no growth aid. This is done through the extension of the catalytic activity time by etching amorphous carbon that deposits. Results suggest that the density and size of the catalyst particles plays a large factor in the concentration of growth aid required to effectively extend growth times. Silicon doping of single-walled tubes was achieved experimentally through the use of the precursor methoxytrimethylsilane inside the precursor solution of an aerosol-assisted chemical vapor deposition system. It is reported here that higher concentrations of the silicon precursor (>0.15wt% in solution) have an adverse effect of the growth of CNTs, effectively poisoning the catalyst. At lower concentrations, however, the silicon precursor contributes to a decrease in average tube diameter and an increase in overall lattice disorder, observed through the use of Raman spectroscopy. Fitting electrical resistance measurements as a function of temperature to Motts variable range hopping models allowed us to determine the mechanism behind electron conductance between nanotubes in bundles. The data suggests that electrons move in a 3-dimensional hopping pattern for bundles of pristine single-walled nanotubes, confirming theoretical previous research. For samples with small concentrations of silicon precursor present, the electron hopping changes to a mix between 2- and 3-dimensional. This indicates that the silicon adatoms act as a scattering point for electrons, directing them to neighboring tubes with a dimensionality factor of two. Further theoretical models were used to study the effect of single or multiple silicon adatoms on neighboring single-walled tubes and their effect on conductance between those tubes. This data suggests that the inclusion of any silicon dopants increases the conductance between the tubes, compared to pristine tubes.Interconnected networks of multi-walled tubes were formed through the use of welding and annealing. The networks were formed through first cross-aligning sheets of CNTs and ensuring physical contact between them. Following this, Ar was bubbled through ethanol and introduced to the sample inside a tube furnace. The ethanol deposited carbon on the nanotube networks, effectively welding them together. Subsequent tubes increased dramatically in diameter from the original tubes, though the outer walls lacked the crystallinity found in the original tubes. Through an anneal at 2200 the overall crystallinity was increased, measured through Raman spectroscopy, high-resolution transmission electron microscopy, and fast Fourier transform. Mechanical testing was performed on the original, welded, and annealed samples to compare tensile strength. The welding process improved the tensile strength by 38%, and the further annealing increased the tensile strength by 66% of the original value. By pre-patterning the iron catalyst used to grow CNTs onto the substrate through the use of photolithography, patterned arrays of vertically aligned CNTs can be formed. These arrays were then utilized as filters to trap viruses through the devices encapsulation in a polymer mold. The CNT-STEP (size tunable enrichment platform) devices were utilized in this work towards the trapping and understanding of the tomato-spotted wilt virus (TSWV). TSWV is a virus that infects upwards of 1000 different plants across the globe and is responsible for massive monetary losses in damages annually. The problems containing the virus stem from the fast nature at which it is able to be spread to neighboring plants, the long time in between inoculation and symptoms (2 weeks), and its inability to be detected prior to symptom onset. Our CNT-STEP devices were utilized to trap the TSWV viruses with the arrays of aligned tubes, allowing larger and smaller contaminants to be removed from the sample. This process effectively hyper-concentrates the viruses, allowing conventional detection methods to be able to detect the viruses. Experimental data shows that the devices were able to effectively trap the viruses, but further processing is required to optimize the system in order to achieve enhancement (where previously undetectable low concentrations are hyper-concentrated in devices in order to be effectively detected).Interconnected networks of single-walled tubes were used as a backbone to support an active battery material (LNMC) to create flexible lithium-ion battery cathodes. Carbon nanotubes are able to effectively replace the metal current collectors and the polymer binders commonly used in Li-ion battery electrodes. By replacing these components with CNTs, the surface area of functional material is increased, while decreasing the weight. Novel methods were utilized to aerosolize powdered LNMC while simultaneously growing and depositing single-walled tubes to create an even dispersion. The CNTs provide mechanical support to the structure, while also being the main contributor to electrical conductivity in the sample. The weight percentage of CNTs in the sample is able to be tuned, with more flexible and mechanically robust samples having >5 wt% CNTs. The ideal samples were grown with between 1-3 wt % CNTs, as higher CNT content made samples increasingly difficult to process, due to inherent adhesion to all surfaces. Simultaneous tensile and resistance measurements were performed to compare growth parameters. Samples were able to withstand 10% elongation at break, but lower stresses than the materials they look to replace. Samples showed overall decreases in resistivity after multiple cycles of elongation and relaxation, indicating small amounts of disorder in the network that are eliminated through stretching. Overall the samples showed excellent promise for use in flexible battery electrodes. Through the use of chemical doping, and strict growth parameter control, the applicability of CNTs can be widely increased.
Book Synopsis Quantitative Analyses of Dispersion, Doping and Electronic Separation of Single Wall HiPco Carbon Nanotubes by :
Download or read book Quantitative Analyses of Dispersion, Doping and Electronic Separation of Single Wall HiPco Carbon Nanotubes written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: As prepared SWNTs are obtained in bundles with a mixture of both metallic and semi conducting tubes. For many specific applications, electronically separated single individual tubes are required and in order to reach these application criteria, the tubes should be processed. This thesis reports on a systematic exploration of methods to routinely process, electronically separate and characterise commercially available single walled carbon nanotubes (SWNTs). Commercially available HiPco SWNTs were dispersed in water with the assistance of 1 % by weight sodium dodecyl benzene sulphate (SDBS). The tubes were dispersed in the water surfactant system through the aid of sonication and centrifugation. The concentration dependent properties were studied in order to establish the aggregation state of the sample. The starting concentration was 5 mg/ml and this was sequentially diluted by a factor of two down to 1.2 x 10-3 mg/ml. UV/Vis/NIR absorption, Raman spectroscopy and atomic force microscopy (AFM) were performed. Using the Lambert Beer law the critical debundling point (CDP) was found to be 0.07±0.03 mg/ml and the extinction coefficient at 600 nm was found to be 215 mL mg-1 m-1 for low concentrations (individual tubes) and 99.5 mL mg-1 m-1 for higher concentrations (bundles). Once establishing the CDP, chiral indices of the tubes were determined by curve fitting the UV/Vis/NIR absorption spectrum and the Radial Breathing Modes (RBM) of the Raman spectrum. Though the chiral indices of the tubes were obtained from two different methods, the values converged enabling UV/Vis/NIR and Raman spectroscopy to be used for routine characterisation. A quantitative analysis of doping of individual tubes at the CDP was conducted by varying the pH from 1 to 13 and monitoring the Raman spectrum. A drastic change in RBM of the Raman spectrum was observed. Mixed Gaussian and Lorentzian line shapes were fitted, and the doping behaviour was modelled using a simple protonation model. The pro.
Book Synopsis Correlation Between Raman Spectroscopy and Electron Microscopy on Individual Carbon Nanotubes and Peapods by : Christian Spudat
Download or read book Correlation Between Raman Spectroscopy and Electron Microscopy on Individual Carbon Nanotubes and Peapods written by Christian Spudat and published by Forschungszentrum Jülich. This book was released on 2010 with total page 147 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Probing Interaction and Dispersion of Carbon Nanotubes in Metal and Polymer Matrices by : Ekaterina Pavlenko
Download or read book Probing Interaction and Dispersion of Carbon Nanotubes in Metal and Polymer Matrices written by Ekaterina Pavlenko and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The incorporation of carbon nanotubes (CNTs) into polymers and metals modifies their intrinsic properties. Dispersing CNTs uniformly in a matrix remains challenging due to strong tube agglomeration. Raman spectroscopy is a compelling technique to detect the presence of CNTs and their interaction with the environment. In this work, Raman spectroscopy is applied in association with other techniques to investigate CNTs in a metallic or polymer matrix. Doping with superacids, analysis of defects in friction wear and CNT dispersion are investigated. Statistical analysis of Raman images are used to generate histograms of Raman bands maps in order to estimate the amount of CNTs and their dispersion. The diffusion of a Poly (Ether Ether Ketone) PEEK thermoplastic polymer into agglomerated carbon nanotubes when annealing on the surface of a polymer sheet is studied by Raman imaging and transmission electron microscopy. Electronic transport measurements as a function of temperature and CNT concentration show high electrical conductivity consistent with the formation of a uniform percolating CNT network.
Book Synopsis Raman Spectroscopy of Double Walled Carbon Nanotubes with Different Metallic and Semiconducting Configurations by : Federico Villalpando Páez
Book Synopsis Electronic Properties of Carbon Nanotubes by : Jose Mauricio Marulanda
Download or read book Electronic Properties of Carbon Nanotubes written by Jose Mauricio Marulanda and published by IntechOpen. This book was released on 2011-07-27 with total page 698 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon nanotubes (CNTs), discovered in 1991, have been a subject of intensive research for a wide range of applications. These one-dimensional (1D) graphene sheets rolled into a tubular form have been the target of many researchers around the world. This book concentrates on the semiconductor physics of carbon nanotubes, it brings unique insight into the phenomena encountered in the electronic structure when operating with carbon nanotubes. This book also presents to reader useful information on the fabrication and applications of these outstanding materials. The main objective of this book is to give in-depth understanding of the physics and electronic structure of carbon nanotubes. Readers of this book should have a strong background on physical electronics and semiconductor device physics. This book first discusses fabrication techniques followed by an analysis on the physical properties of carbon nanotubes, including density of states and electronic structures. Ultimately, the book pursues a significant amount of work in the industry applications of carbon nanotubes.
Book Synopsis Raman Scattering and Optical Spectroscopies of Carbon Nanotubes by : Huy Nam Tran
Download or read book Raman Scattering and Optical Spectroscopies of Carbon Nanotubes written by Huy Nam Tran and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Synthesis and Characterization of Nitrogen, Boron, Chlorine and Fluorine Doped Carbon Nanotubes by : Adeniyi Olugbenga Osikoya
Download or read book Synthesis and Characterization of Nitrogen, Boron, Chlorine and Fluorine Doped Carbon Nanotubes written by Adeniyi Olugbenga Osikoya and published by . This book was released on 2013 with total page 278 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon nanotubes (CNTs) doped with nitrogen, boron, chlorine and fluorine have been synthesized in a catalytic chemical vapour deposition (CCVD) reactor at 700 and 800 °C, using cobalt and silver as catalysts supported on magnesium oxide. The synthesized carbon nanotubes were characterized by Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Raman spectroscopy, X-ray diffraction spectroscopy (XRD), Thermogravimetric analysis (TGA) and Energy dispersive spectroscopy (EDS). Carbon nanotubes doped with nitrogen were found to have internal bamboo shaped structures in the TEM results. Carbon nanotubes doped with boron were also found to have compartmentalized internal structures with narrower inner diameter compared to the outer diameter. SEM characterization shows that carbon nanotubes doped with chlorine have tapered or spike-like external morphology. While fluorine doped carbon nanotubes shows the formation of a lot of carbon nanospheres and, amorphous carbon in addition to the formation of tubular structures with rough and grainy-like external morphology.
Book Synopsis A Spectroscopic Investigation Into the Low-frequency Raman Spectrum of Single Wall Carbon Nanotubes by : Michelle N. Galvin
Download or read book A Spectroscopic Investigation Into the Low-frequency Raman Spectrum of Single Wall Carbon Nanotubes written by Michelle N. Galvin and published by . This book was released on 2010 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781721580699 Total Pages :28 pages Book Rating :4.5/5 (86 download)
Book Synopsis Diagnostics of Carbon Nanotube Formation in a Laser Produced Plume by : National Aeronautics and Space Administration (NASA)
Download or read book Diagnostics of Carbon Nanotube Formation in a Laser Produced Plume written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-20 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon nanotubes, elongated molecular tubes with diameters of nanometers and lengths in microns, hold great promise for material science. Hopes for super strong light-weight material to be used in spacecraft design is the driving force behind nanotube work at JSC. The molecular nature of these materials requires the appropriate tools for investigation of their structure, properties, and formation. The mechanism of nanotube formation is of particular interest because it may hold keys to controlling the formation of different types of nanotubes and allow them to be produced in much greater quantities at less cost than is currently available. This summer's work involved the interpretation of data taken last summer and analyzed over the academic year. The work involved diagnostic studies of carbon nanotube formation processes occurring in a laser-produced plume. Laser ablation of metal doped graphite to produce a plasma plume in which carbon nanotubes self assemble is one method of making carbon nanotube. The laser ablation method is amenable to applying the techniques of laser spectroscopy, a powerful tool for probing the energies and dynamics of atomic and molecular species. The experimental work performed last summer involved probing one of the metal catalysts, nickel, by laser induced fluorescence. The nickel atom was studied as a function of oven temperature, probe laser wavelength, time after ablation, and position in the laser produced plume. This data along with previously obtained data on carbon was analyzed over the academic year. Interpretations of the data were developed this summer along with discussions of future work. The temperature of the oven in which the target is ablated greatly influences the amount of material ablated and the propagation of the plume. The ablation conditions and the time scale of atomic and molecular lifetimes suggest that initial ablation of the metal doped carbon target results in atomic and small molecular species. The metal ato
