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Rathna, A. "Theoretical Studies Of Fullerenes And Fullerene Derivatives." Thesis, Indian Institute of Science, 1994. https://etd.iisc.ac.in/handle/2005/111.
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The detection of Ceo and Cro in 1985 and the subsequent development of a preparative procedure have opened up a new area of research in carbon chemistry. The study of physico-chemical properties of these molecules is currently being pursued with great interest. The goal of the present thesis is to provide simple generalization concerning the structure and bonding which would be of useful interpretive value in understanding the reactivity patterns. The stability of a large number of derivatives have been examined at uniform levels of semiempirical MO theories. The results are shown to be consistent with simple localized bonding model of molecular and electronic structure of Ceo and Cro. Additional factors influencing the relative stabilities of fullerene derivatives are also analysed.
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Rathna, A. "Theoretical Studies Of Fullerenes And Fullerene Derivatives." Thesis, Indian Institute of Science, 1994. http://hdl.handle.net/2005/111.
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The detection of Ceo and Cro in 1985 and the subsequent development of a preparative procedure have opened up a new area of research in carbon chemistry. The study of physico-chemical properties of these molecules is currently being pursued with great interest. The goal of the present thesis is to provide simple generalization concerning the structure and bonding which would be of useful interpretive value in understanding the reactivity patterns. The stability of a large number of derivatives have been examined at uniform levels of semiempirical MO theories. The results are shown to be consistent with simple localized bonding model of molecular and electronic structure of Ceo and Cro. Additional factors influencing the relative stabilities of fullerene derivatives are also analysed.
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Rabinovich, Daniel. "A molecule for football fans." Revista de Química, 2016. http://repositorio.pucp.edu.pe/index/handle/123456789/99465.
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Una molécula para los aficionados al fútbol (El descubrimiento de los Fullerenos y su aparición en las estampillas del Reino Unido)A molecule for football fans (The discovery of fullerenes and their appearance on stamps UK)
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Goel, Anish. "Combustion synthesis of fullerenes and fullerenic nanostructures." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/32334.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2002.Includes bibliographical references (leaves 123-132).
Fullerenes are molecules comprised entirely of sp²-bonded carbon atoms arranged in pentagonal and hexagonal rings to form a hollow, closed-cage structure. Buckyballs, a subset which contains C₆₀ and C₇₀, are single-shell molecules while fullerenic nanostructures can contain many shells and over 300 carbon atoms. Both fullerenes and nanostructures have an array of applications in a wide variety of fields, including medical and consumer products. Fullerenes were discovered in 1985 and were first isolated from the products of a laminar low-pressure premixed benzene/oxygen/argon flame operating at fuel-rich conditions in 1991. Flame studies indicated that fullerene yields depend on operating parameters such as temperature, pressure, residence time, and equivalence ratio. High-resolution transmission electron microscopy (HRTEM) showed that the soot contains nanostructures, including onions and nanotubes. Although flame conditions for forming fullerenes have been identified, the process has not been optimized and many flame environments of potential interest are unstudied. Mechanistic characteristics of fullerene formation remain poorly understood and cost estimation of large-scale production has not been performed. Accordingly, this work focused on: 1) studying fullerene formation in diffusion and premixed flames under new conditions to identify optimal parameters; 2) investigating the reaction of fullerenes with soot; 3) positively identifying C₆₀ molecules in HRTEM by tethering them to carbon black; and 4) providing a cost estimation for industrial fullerenic soot production.
(cont.) Samples of condensable material from laminar low-pressure benzene/argon/oxygen diffusion flames were collected and analyzed by high-performance liquid chroma- tography (HPLC) and HRTEM. The highest concentration of fullerenes in a flame was always detected just above the height where the fuel is consumed. The percentage of fullerenes in condensable material increases with decreasing pressure and the fullerene content of flames with similar cold gas velocities shows a strong dependence on length. A shorter flame, resulting from higher dilution or lower pressure, favors the formation of fullerenes rather than soot, exhibited by the lower amount of soot and precursors in such flames. This indicates a stronger correlation of fullerene consumption to soot levels than of fullerene formation to precursor concentration. The maximum flame temperature seems to be of minor importance in formation. The overall highest amount of fullerenes was found for a surprisingly high dilution of fuel with argon. The HRTEM analysis showed an increase of the curvature of the carbon layers, and hence increased fullerenic character, with increasing distance from the burner up to the point of maximum fullerene concentration, after which it decreases, consistent with the HPLC analysis. The soot shows highly ordered regions that appear to have been cells of fullerenic nanostructure formation. The samples also included fullerenic nanostructures such as tubes and spheroids including highly-ordered multilayered or onion-like structures. Studies of turbulent-like benzene/oxygen/argon diffusion flames showed that these flames produce fullerenes over a wider range of heights than laminar flames but with lower yields.
(cont.) No discernible trend could be detected in the data and the fullerene results were not easily reproducible indicating that such flames are not suitable for fullerene formation. Soot samples were also collected from a well-characterized laminar premixed benzene/oxygen/argon flat flame under new conditions and analyzed by HPLC and HRTEM. Flame studies using secondary injections of benzene or acetylene show that two-stage flames are unsuitable for fullerene production. It seems that secondary fuel has an adverse effect on the formation of fullerenes and creates conditions that are similar to the early stages of a single-stage flame prior to soot formation. This means that fuel must go through the combustion process to form fullerenes and that they cannot be formed simply by organic pyrolysis. Additionally, fullerene data collected in this study show significantly higher yields than in a previous study and the absence of a concentration drop-off. The coexistence of fullerenes and soot does not support but also does not rule out that fullerenes are consumed by soot, as was suggested by diffusion flame data. Given the discrepancy in the data, fullerene consumption was studied in experiments involving pure fullerenes being sublimated into a passing argon gas stream. This gas stream then passed through a carbon black bed. As the fullerenes passed through the bed, a certain percentage reacted with the surface of the particles and the non-reacted material was collected downstream. Experiments at different temperatures indicate that fullerenes are indeed consumed by soot particles but that the consumption is quite slow.
(cont.) The rate coefficient obtained resembles those seen for surface diffusion controlled reactions or for heterogeneous reactions. Extrapolation of the reaction coefficient to flame conditions would indicated that this type of fullerene consumption is not nearly enough to explain the consumption observed in fullerene-forming flames, meaning that fullerenes are consumed by other mechanisms. HRTEM analysis of carbon black with and without tethered fullerenes shows that fullerenes can in fact be observed in TEM micrographs. In this experiment, functionalized C₆₀ molecules were attached to the surface of carbon black particles with a chemical tether. The resulting compound was analyzed by HRTEM and compared with similar analysis of untreated carbon black. The post-treatment carbon black not only has an order of magnitude greater concentration of apparent fullerene structures but size distribution data shows a significant peak at the C₆₀ diameter for the treated sample whereas no peak is observed for the untreated sample. This indicates that the fullerenes have indeed been attached to the particle surface and that they can definitively be seen in images produced from HRTEM. Lastly, a model was built to estimate the cost of the large scale production of fullerenic soot. This model was based on current carbon black technology and takes into account operating parameters specific for fullerene production. Sensitivity analyses performed on the model indicate that soot yield and fuel price are the most important factors in determining production cost while electricity costs are minimally important.
(cont.) It was seen that operating pressure and equipment lifetime are negligible in the final cost. Overall, combustion holds immense promise to be a much cheaper and more efficient alternative to the current method of commercial fullerene production.
by Anish Goel.
Ph.D.
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Dybek, Aneta. "Production and Characterisation of Fullerenes, Fullerene Derivatives and Fullerene-Based Electronic Devices." Thesis, Queen Mary, University of London, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.522327.
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Samoylova, Nataliya. "Cluster-based redox activity in Endohedral Metallofullerenes:." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-230132.
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Endohedral fullerenes are closed carbon shells encapsulating molecular or ionic species in their inner space. Obtained for the first time in 1985, endohedral metallofullerenes (EMFs) remain in focus of research for many years with a broad variety of metal atoms, endohedral cluster and cage sizes being reported.
Electrochemical studies of endohedral metallofullerenes are of particular interest because of the more complex redox behavior in comparison to empty fullerenes. The EMF molecules can be considered as a combinations of positively charged cluster and negatively charged carbon shell “ligand”, and both constituents can be redox active. A cage-based electrochemical activity is more common, in particular, the most abundant nitride clusterfullerenes generally have redox-active cages. Cluster-based electrochemical activity is less common and can be revealed via unexpected redox behavior (e.g., shifted potential when compared to analogous molecules, potential metal dependence) and with the use of spectroscopic methods.
Here we report electrochemical and EPR studies of three EMF families: (i) M2@C82-C3v and M2@C82-Cs dimetallofullerenes with a covalent bonding between two metal atoms, (ii) M2@C80(CH2Ph) dimetallofullerene derivatives with single-occupied metal-bonding orbital, and (iii) M2TiC@C80 EMFs with endohedral Ti(IV) (M is either Sc or Y or a lanthanide). For the first two families, the metal-metal bonding orbital has been found to be redox active: in M2@C82, the double-occupied M-M bonding orbital is involved in the first oxidation process, while in M2@C80(CH2Ph) the unoccupied component of single-occupied metal-bonding orbital acts as the LUMO, accepting one electron during the first reduction step. Thus, single electron transfer reactions in both cases lead to the changes in the magnetic properties of EMFs, which is especially well revealed by EPR spectroscopy. For the series of M2TiC@C80 EMFs, the first reduction predominantly occurs on internal Ti atom and can be described as TiIV/TiIII redox process. Due to the variation of the size of the Ti ion in different oxidation states, reduction changes the inner strain of the cluster, leading to a large variability of the TiIV/TiIII reduction potential in dependence on the size of the formally inert lanthanide metal in M2TiC@C80.
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Gritsina, V. O., Наталія Ігорівна Муліна, Наталия Игоревна Мулина, and Nataliia Ihorivna Mulina. "Fullerenes." Thesis, Сумський державний університет, 2013. http://essuir.sumdu.edu.ua/handle/123456789/31130.
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A fullerene is any molecule composed entirely of carbon, in the form of a hollow sphere, ellipsoid or tube. Spherical fullerenes are also called buckyballs. Fullerenes are similar in structure to graphite.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/31130
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Peel, Jason Alexander. "The synthesis and characterisation of some new organometallic derivatives of [60]fullerene." Thesis, University of Reading, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389639.
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Terrones-Maldonado, Mauricio. "Production and characterisation of novel fullerene-related materials : nanotubes, nanofibres and giant fullerenes." Thesis, University of Sussex, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361404.
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Coheur, Pierre-François. "Spectroscopie électronique de fullerenes." Doctoral thesis, Universite Libre de Bruxelles, 1999. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/211941.
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Kooistra, Floris Berend. "Fullerenes for organic electronics." [S.l. : Groningen : s.n. ; University Library of Groningen] [Host], 2007. http://irs.ub.rug.nl/ppn/305161504.
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Chang, Kai-Chin. "Investigation of higher fullerenes." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2013. http://dx.doi.org/10.18452/16700.
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Trifluoromethylierung von Mischungen hoeherer Fullerene mit CF3I wurde in Ampullen bei 400-420 Grad Celsius und 500-600 Grad Celsius durchgefuehrt. Die Produktmischungen wurden mittels mehrstufiger HPLC getrennt. In mehreren Versuchen konnten aus den isolierten HPLC-Fraktionen Kristalle fuer die Roentgenstrukturanalyse gewonnen werden. Die folgenden Strukturen der CF3-Derivate der Fullerene C84, C86 und C88 wurden bestimmt: 1 Isomer von C84(4)(CF3)12, C84(11)(CF3)10, C84(11)(CF3)12, C84(11)(CF3)16, C84(16)(CF3)8, C84(16)(CF3)14, C84(18)(CF3)10, C84(18)(CF3)12, C84(22)(CF3)20, C84(23)(CF3)8, C84(22)(CF3)10, C84(22)(CF3)12, C84(22)(CF3)18, C86(17)(CF3)10, C86(17)(CF3)16, C88(33)(CF3)16, C88(33)(CF3)18 und C88(33)(CF3)20. 2 Isomere von C84(22)(CF3)12, C84(22)(CF3)14 und C84(23)(CF3)14. 3 Isomere von C84(11)(CF3)14. 4 Isomere von C84(22)(CF3)16. Die Additionsmuster der Strukturen wurden diskutiert. Die experimentell nachgewiesenen Strukturen wurden mit berechneten Modellstrukturen verglichen. Dabei wurde auch die Stabilitaet der experimentellen Strukturen vorausgesagt. Zusaetzlich wurden die moeglichen Reaktionspfade fuer die Bildung hoeherer Derivate ausgehend von niedrigen Derivaten diskutiert. Sie zeigen, dass die Regioselektivitaet der Addition vom Kaefigisomer abhaengig ist. Die Reaktionspfade von vier Fullerenkaefigen werden in dieser Arbeit vorgestellt. C84(11)(CF3)10 --> C84(11)(CF3)16 C84(22)(CF3)2 --> C84(22)(CF3)20 C84(23)(CF3)10 --> C84(23)(CF3)18 C86(17)(CF3)10 --> C86(17)(CF3)16Trifluoromethylation of higher fullerene mixtures with CF3I was performed in ampoules at 400 to 420 degree Celsius and 500 to 600 degree Celsius. The obtained product mixtures were separated by multistep HPLC. Subsequent crystal growth and X-ray diffraction measurements allowed for structural characterization of the CF3 derivatives of fullerenes C84, C86 and C88 listed as the following. 1 isomer of C84(4)(CF3)12, C84(11)(CF3)10, C84(11)(CF3)12, C84(11)(CF3)16, C84(16)(CF3)8, C84(16)(CF3)14, C84(18)(CF3)10, C84(18)(CF3)12, C84(22)(CF3)20, C84(23)(CF3)8, C84(22)(CF3)10, C84(22)(CF3)12, C84(22)(CF3)18, C86(17)(CF3)10, C86(17)(CF3)16, C88(33)(CF3)16, C88(33)(CF3)18 and C88(33)(CF3)20. 2 isomers of C84(22)(CF3)12, C84(22)(CF3)14 and C84(23)(CF3)14. 3 isomers of C84(11)(CF3)14. 4 isomers of C84(22)(CF3)16. The molecular structures of isolated isomers were discussed in terms of their addition patterns and relative formation energies. DFT calculations were used to predict stable molecular structures of the CF3 derivatives. Calculated model structures have been compared with the experimental ones. In addition, the reaction pathways from the lower derivatives to higher ones of selected compounds were predicted. The pathways indicate the regioselectivity of additions depending on the fullerene cage isomer. Reaction pathways are presented for four fullerene cages in this work. C84(11)(CF3)10 --> C84(11)(CF3)16 C84(22)(CF3)2 --> C84(22)(CF3)20 C84(23)(CF3)10 --> C84(23)(CF3)18 C86(17)(CF3)10 --> C86(17)(CF3)16
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Wang, Yonggang. "Transport and retention of fullerene-based nanoparticles in water-saturated porous media." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29782.
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Thesis (Ph.D)--Civil and Environmental Engineering, Georgia Institute of Technology, 2010.Committee Chair: Pennell, Kurt; Committee Member: Hughes, Joseph; Committee Member: Kim, Jaehong; Committee Member: Snyder, Robert; Committee Member: Yiacoumi, Sotira. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Almutlaq, Nasser. "Quantum control of the electronic and thermal properties of fullerenes and exohedral fullerenes." Thesis, Lancaster University, 2018. http://eprints.lancs.ac.uk/125708/.
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In recent years, driven by the need to downsize to the molecular level, advances in technology has made the manufacture of nanoscale devices possible. In this thesis I will investigate the theoretical electronic and thermal properties of a carbon based class of nanoscale materials by examining the possibility of using fullerenes and decachlorofullerenes as building blocks towards viable molecular scale devices. In particular I have looked at ways to enhance the electronic communication between fullerenes through introducing exohedral varients, which I found to have a positive effect on the electronic and thermoelectric properties. The methods used in this work are based on density functional theory, combined with quantum transport calculations using Greens functions. Fullerenes are promising building blocks for nano-scale electronics, as they have relatively large spherical surface area and are geometrically symmetric. If fullerenebased thermoelectricity is to become a viable technology, then fullerenes exhibiting both positive and negative Seebeck coefficients will be needed and therefore I also calculate the thermoelectric properties of the naturally occurring fullerene C60 known as the buckyball together with an exohedral example namely C50Cl10. C60 is known to have a negative Seebeck coefficient of S which varies in the range of - 18 to -23 μV/K and therefore in this thesis I address the challenge of identifying a fullerene with a positive-Seebeck-coefficient. I investigated the thermoelectric properties of single-molecule junctions of the exohedral fullerene C50Cl10 connected to gold electrodes and found that it has a positive Seebeck coefficient. Furthermore, in common with C60, the Seebeck coefficient can be increased by placing more than one C50Cl10 in series. For a single C50Cl10, I find S=+8 μV/K and for two C50Cl10’s in series I find S=+30 μV/K. I also find that the C50Cl10 monomer and dimer have power factors of 0.5×10-5 W/m.K2 and 6.0×10-5 W/m.K2 respectively. These results demonstrate that exohedral fullerenes could provide a new class of thermoelectric materials with desirable properties, which complement those of all-carbon fullerenes, thereby enabling the boosting of the thermovoltage in all-fullerene tandem structures. I calculate the structural and electronic and thermoelectrics properties of carbon nanotube peapods. In contrast with carbon-only peapods, the magnitude of this effect is sensitive to the orientation and spacing of the fullerenes and exohedral fullerenes as a consequence, a rotation or translation of the C50Cl10 can cause the zero-bias electrical conductance to switch, as a result of that the new possibilities of engineering the transport properties of carbon nanotube peapods.
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Kincer, Matthew Ryan. "Polymeric templating and alignment of fullerenes." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42879.
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Fullerene research has advanced to elevated levels in a short period of time due to the unique chemical and physical properties of the caged molecule that have been utilized in numerous applications. Due to the spherical shape of the fullerene molecule which allows for a hollow cavity, encapsulation of atoms or small molecules can occur within the ball structure. This encapsulation creates an endohedral component that is limited from interacting with other molecules which creates potential of control over electronic information of the isolated molecule. Endohedral fullerenes have the potential as serving as the base unit in a quantum computer if control over global alignment is attained. Thus, by using the inherent self-assembling capabilities of some organic materials, ordered endohedral fullerenes can be achieved. This dissertation investigates the ability to use self-assembling strategies to obtain alignment which include ordering within a morphologically controlled copolymer matrix, forming a supramolecular polymer complex with cyclodextrin, and encapsulation within the helical wrap of polymer chains. The ultimate goal is to understand the dynamics that control association and orientation of varying fullerene-based molecules in each strategy in order to maximize control over the final alignment of endohedral elements.
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Morinaka, Yuta. "Studies on Properties of Endohedral Fullerenes and Development of Fullerene Derivatives for Organic Photovoltaic Devices." 京都大学 (Kyoto University), 2013. http://hdl.handle.net/2433/174889.
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Yang, Yi-Fan [Verfasser], and Lorenz S. [Akademischer Betreuer] Cederbaum. "Electronic States of Fullerene Anions and Endohedral Fullerenes / Yi-Fan Yang ; Betreuer: Lorenz S. Cederbaum." Heidelberg : Universitätsbibliothek Heidelberg, 2020. http://d-nb.info/1212935608/34.
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Korica, Sanja. "Photoionisation and photofragmentation of fullerenes." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=979218632.
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Meyer, Carola. "Endohedral fullerenes for quantum computing." [S.l. : s.n.], 2003. http://www.diss.fu-berlin.de/2003/296/index.html.
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Denning, Mark Simon. "Intercalation chemistry of higher fullerenes." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343444.
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Crowley, Colin. "Fullerenes from polycyclic aromatic hydrocarbons." Thesis, University of Sussex, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360582.
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Yadav, Tapesh K. "Thermally metastable fullerenes in flames." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/28067.
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Campo, Angela. "Novel Synthesis of Polyhydrogenated Fullerenes." Wright State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=wright1292563030.
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Tinker, Frank Albert. "Carbon-sublimation production of fullerenes." Diss., The University of Arizona, 1995. http://hdl.handle.net/10150/187221.
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Carbon-sublimation production of fullerenes enjoys wide use in both experimental and industrial application worldwide. Although it has been nearly five years since the inception of the technique, little is known about the roles various parameters play in the production process. This work attempts to shed light, both experimentally and theoretically, on the basic processes at work in this type of fullerene production. Experimental results herein show that a functional relationship exists among the C₆₀, C₇₀, C₇₆, C₇₈, and C₈₄ fullerenes produced in carbon arcs. This result is interpreted to mean that an equilibrium description of the production process may be valid. Theoretical calculations are then offered in support of such a view. The theory goes on to show details of an equilibrium description that reproduce essential features of fullerene mass-spectra. It is shown that equilibrium abundances of n-atom-sized clusters are highly dependent on the stoichiometric equation chosen to describe the system. However, common traits of the investigated equilibrium descriptions lead to useful conclusions.
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Griffitts, Fletcher G. "Fullerenes in Solar Energy Cells." Digital Commons @ East Tennessee State University, 2017. https://dc.etsu.edu/honors/394.
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This project involves controlling and characterizing the morphology of the active layer in a special type of organic photovoltaics (OPVs), consisting of porphyrin-fullerene composites, with emphasis on electron exchange interactions between the two components. The Vienna Ab Initio Simulation Package (VASP) is applied to model a variety of donor-acceptor complexes containing fullerene and porphyrin in terms of their stabilities as well as their geometric, electronic, and charge transfer features. The goal is to identify supramolecular chain structures with highest occupied molecular orbitals (HOMOs) and lowest unoccupied molecular orbitals (LUMOs) that may serve as electron (hole) transfer channels in a photovoltaic device.
A stable structure, involving the planar adsorption of a porphyrin unit on a C60 hexagon, has been identified. The results for fullerene have been extended to phthalocyanine–fullerene dyads where the fullerene-derived unit Phenyl-C61-butyric acid methyl ester (PCBM) is connected to a porphyrin analogous electron donor through two oxygen-linked benzene rings. In both cases, the HOMO is located on the porphyrin segment, the LUMO on the fullerene component. As a fullerene, PCBM is a material of very high electron affinity, but it has better solubility properties than fullerene. It is often used in plastic solar cells or flexible electronics in conjunction with electron donor materials such as P3HT or other polymers. The results of our work contribute to the ongoing effort of using computational modeling to identify fullerene-based materials of potential relevance for organic photovoltaics.
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Abella, Guzman Laura. "Computations on Fullerenes: Characterization, Reactivity and Growth." Doctoral thesis, Universitat Rovira i Virgili, 2017. http://hdl.handle.net/10803/460692.
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Aquesta Tesi titulada ‘Computations on Fullerenes: Characterization, Reactivity and Growth’ es focalitza amb els mecanismes de formació i caracterització de ful·lerens prèviament detectats als experiments. Són caixes tancades de carboni formades per hexàgons i dotze pentàgons. Hem col·laborat amb diferents grups experimentals, per tant, ens hem centrat en entendre i racionalitzar els seus experiments. Diferents models de formació de ful·lerens han estat proposats, però encara avui segueix sent un misteri. Els nostres estudis donen completament suport al mecanisme de creixement bottom-up proposat pel Prof. Kroto. Aquest mecanisme ha estat estudiat per càlculs estàtics de DFT i per dinàmica molecular de Car-Parrinello. Una exploració exhaustiva dels isòmers més favorables, així com les superfícies d’energia potencial associades a les insercions d’unitats C2 als ful·lerens i les topologies de les estructures involucrades, han ajudat al desenvolupament d’aquest projecte. Aquest procés d’inserció és exotèrmic/exergònic, i encara que les barreres d’energia lliure són elevades, es poden veure superades a la temperatura de formació de ful·lerens (2000 K). Els isòmers més abundants del Ti@C2n (2n=26-48) i Sc3N@C2n (2n=68-80) s’han relacionat mitjançant unitats C2 i, en alguns casos, alguna isomerització del tipus Stone-Wales. Respecte a la detecció i aïllament dels metal·loful·lerens endoèdrics, ens hem centrat en la seva caracterització. La cloració dels ful·lerens també ha estat estudiada, ja que ha sorgit com una poderosa eina en el món dels derivats de ful·lerens. Famílies de C2n (2n=50,60,66,68,etc.) han estat trobades com cloroful·lerens. Els nostres resultats prediuen que la cloració s’esdevé un cop es formada la caixa neutra a temperatures més baixes de 2000 K, mitjançant l’addició de radical lliure i tenint en compte les distribucions del HOMO i de la densitat d’spin. La majoria dels nostres projectes han estat d’acord amb els resultats experimentals.La Tesis titulada ‘Computations on Fullerenes: Characterization, Reactivity and Growth’ se focaliza con los mecanismos de formación y caracteritzación de fullerenos previamente detectados a los experimentos. Son cajas cerradas de carbono formadas por hexágonos y doce pentágonos. Hemos colaborado con diferentes grupos experimentales, por tanto, nos hemos centrado en entender y racionalizar sus experimentos. Diferentes modelos de formación han sido propuestos, pero todavía hoy sigue siendo un misterio. Nuestros estudios dan soporte al mecanismo de crecimiento bottom-up propuesto por el Prof. Kroto. Este mecanismo ha sido estudiado mediante cálculos estáticos de DFT i por dinámica molecular de Car-Parrinello. Una exploración exhaustiva de los isómeros más favorables, así como las superficies de energía potencial asociadas a las inserciones de unidades C2 a los fullerenos y las topologías de las estructures involucradas, han ayudado al desarrollo de este proyecto. Este proceso de inserción es exotérmico/exergónico, y todavía que las barreras de energía libre son elevadas, se pueden ver superadas a la temperatura de formación de fullerenos (2000 K). Los isómeros más abundantes del Ti@C2n (2n=26-48) y Sc3N@C2n (2n=68-80) se han relacionado mediante unidades C2 y, en algunos casos, alguna isomerización del tipo Stone-Wales. Respecto a la detección y aislamiento de los metallofullerenos endoédricos, nos hemos centrado en su caracteritzación. La cloración de los fullerenos también ha sido estudiada, ya que ha surgido como una poderosa herramienta en el mundo de los derivados de fullerenos. Familias de C2n (2n=50,60,66,68,etc.) han sido encontradas como clorofullerenos. Nuestros resultados predicen que la cloración se forma una vez es formada la caja neutra a temperaturas más bajas de 2000 K, mediante la adición de radical libre y teniendo en cuenta las distribuciones del HOMO y de la densidad de espín. La mayoría de nuestros proyectos han estado de acuerdo con los resultados experimentales.
The Thesis titled ‘Computations on Fullerenes: Characterization, Reactivity and Growth’ is mainly focused on the formation mechanisms and characterization of fullerenes previously detected in experiments. These molecules are closed carbon cages formed by only hexagons and twelve pentagons. Most part of our research has been carried out in collaboration with different experimental groups, therefore we aimed to understand and rationalize their experiments. Although many hypothetical models have been proposed, the fullerene formation mechanism is still a mystery. Our studies rules out the bottom-up mechanism as a model of fullerene formation. We have explored this mechanism by means of static DFT and Car-Parrinello molecular dynamics calculations for series of different endohedral fullerenes. A comprehensive exploration of the most favourable isomers, potential energy surfaces associated with the successive C2 insertions and topologies of the involved structures, helped us to develop this project. The insertion of a C2 unit to already formed EMF is always an exothermic/exergonic process, and the free energy barriers for each step are attainable at temperature of fullerene formation (2000 K). The most abundant isomers of Ti@C2n (2n=26-48) and Sc3N@C2n (2n=68-80) are formally linked by direct C2 insertions and in a few cases by additional Stone-Wales transformations. Regarding the detection and isolation of endohedral metallofullerenes let us to perform a computational study of the rationalization and characterization of these isomers. Chlorination has emerged as a powerful tool in fullerene derivatives. Several C2n families (2n=50,60,66,68,etc.) have been found to show cages exohedrally chlorinated. According to our results, chlorination would take place at a temperature significantly lower than 2000 K by free radical addition considering the HOMO and the spin density distributions of the pristine cage and intermediates, once the lowest energy neutral isomers are formed. Most of our projects resulted in suitable and in agreement with experiments.
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Mo^n, Dyfrig. "Fullerene crystallisation in Fullerene/Polymer bilayers." Thesis, Swansea University, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.678620.
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Marcusanu, Mihaela. "The classification of ℓ₁-embeddable fullerenes." Bowling Green, Ohio : Bowling Green State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=bgsu1180115123.
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King, David J. "Modelling of fullerenes on silicon surfaces." Thesis, Loughborough University, 2008. https://dspace.lboro.ac.uk/2134/4644.
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An extension to the capabilities of an ab-initio density functional theory package, PLATO, has been undertaken. This concerned the calculation of Slater-Koster integrals and their derivatives, via the recursive methods initially proposed by Podolskiy and Vogl, and developed by Elena and Meister. This extension provides the ability to include the previously unavailable f -orbitals (and beyond) within PLATO calculations. Calculations have been performed, including f - orbitals, on silver, silicon and nitrogen systems. The results show a modest improvement, in terms of the convergence of the total energies calculated, when comparing the calculations including f -orbitals to those without. The impact on computational time is mixed, with both decreases and increases in compuational time demonstrated, dependent on the system in question and the type of calculation performed. The interactions between C60 molecules and the Si (100) surface, as well as the interactions between the endohedrally doped N@C60 molecules and the Si (100) surface have been explored via ab-initio total energy calculations. Configurations which have the cage located upon the dimer row bonded to two dimers (r2) and within the dimer trench bonded to four dimers (t4) have been investigated, as these have previously been found to be the most stable for the C60 molecule. We show that our results for the adsorption of the C60 molecule upon the Si (100) surface are comparable with previous studies. We have investigated the differences between the adsorption of the C60 and N@C60 molecules upon the Si (100) surface and found that there are only minimal differences. It is shown that the effects on the endohedral nitrogen atom, due to its placement within the fullerene cage, are small. Bader analysis has been used to explore differences between the C60 and N@C60 molecules. The interactions between pairs of C60 molecules adsorbed upon the Si (100) surface have also been studied. The same selection of t4 configurations used for the isolated fullerenes is explored in all possible pairs of fullerene configuration combinations. A previous study by Frangou explored pairs of fullerenes in adjacent bonding sites on the silicon surface, this study, however, investigates bonding sites separated by one silicon dimer. Comparisons between the two studies confirm the trend of the combinations becoming more favourable at a greater fullerene separation. There are several cases where the combined pair of fullerenes are less favourable than the two isolated cases, so these are studied indepth. The separation chosen in our study reflects the experimental separation observed by Moriarty et al..
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Frangou, Paul Christopher. "Modelling of fullerenes on silicon surfaces." Thesis, Loughborough University, 2008. https://dspace.lboro.ac.uk/2134/13499.
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The interactions between fullerene cages and Si {100) surfaces are studied using density functional theory. This has previously been studied and the molecules are found to bind in four different locations upon the dimerised Si (100) surface. These are above the dimer row bound to one or two dimers (rl and r2 respectively) and within the dimer trench bound to two or four dimers (t2 and t4 respectively). Here we focus on the r2 and t4 configurations as these were found to have stronger binding energies due to the four bonds forming between cage and surface rather than two. The rl and t2 sites are actually metastable and minor displacements of the cages result in them falling in to one of the energy minima of the t4 and r2 sites. All of the configurations discovered by Godwin et al. via PLATO, are verified as are three of the additional configurations from the study by Hobbs et al. which used the SIESTA software package. A more complete basis set is employed here to ascertain the effect it has upon the basis set superposition error. It is found to reduce it to negligible levels.
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Brown, Craig. "Solid state chemistry of selected fullerenes." Thesis, University of Sussex, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264552.
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Wietor, Jean-Luc. "Recognition of fullerenes and quadruplex DNA." Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.613292.
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Al-Matar, Hamad M. "Alkylation of [60]- and [70]fullerenes." Thesis, University of Sussex, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326917.
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Krachmalnicoff, Andrea. "Synthesis of small molecule endohedral fullerenes." Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/377598/.
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Alekseeva, О. V., N. A. Bagrovskaya, and A. V. Noskov. "Polystyrene Film Composites Filled with Fullerenes." Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35444.
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It is shown by methods of electronic microscopy that polystyrene film forms during evaporation of sol-vent from a solution of polystyrene in o-xylene. This film consists of polystyrene molecules integrated in aggregates. According to IR-spectroscopy data it was suggested that noncovalent interaction of phenyl ring with fullerene molecule occurs in the composite material. The studied films possess antimicrobial proper-ties.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35444
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Rainey, Joe Seaburn. "Synthesis of fullerenes and metallic fullerenes by the utilization of an argon radio frequency inductively coupled plasma." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/27679.
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Joutsensaari, Jorma. "Aerosol synthesis of nanostructured, ultrafine fullerene particles /." Espoo [Finland] : Technical Research Centre of Finland, 1999. http://www.vtt.fi/inf/pdf/publications/1999/P400.pdf.
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Valencia, Maturana Ramon. "Electronic structure and reactivity of endohedral fullerenes." Doctoral thesis, Universitat Rovira i Virgili, 2011. http://hdl.handle.net/10803/34756.
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En este trabajo abarcamos el estudio de la estructura electrónica de una serie de fulerenos denominados fulerenos endoédricos, así como también su reactividad.
En este trabajo de tesis previo, se define lo que se conoce como la regla del gap (LUMO-3)-(LUMO-4), la cual indica que aquellas cajas fulerénicas vacías cuyo gap entre el tercer y cuarto orbitales desocupados sea mayor grande tendrán la capacidad de aceptar la transferencia de seis electrones desde un clúster metálico. En el capítulo 3, la regla del gap (LUMO-3)-(LUMO-4) ha sido extendida para aquellas cajas fulerénicas de hasta 100 átomos de carbono. También se ha analizado la reactividad exoédrica del M3N@D5h-C80 en una reacción de cicloadición de Diels-Alder con 1, 3-butadieno sobre los diferentes tipos de enlaces de la caja D5h-C80.
En el capítulo 4 estudiamos la estructura electrónica de los fulerenos endoédricos con carburos metálicos (M2C2@C82). Se han estudiado seis isómeros de Sc2C2@C82, confirmando que su estructura electrónica se puede explicar de manera sencilla con el modelo iónico (clúster)4+@(caja)4–, adoptando el carburo metalico diferentes orientaciones dentro de la caja de C82 .
En el capítulo 5 hemos estudiado la estructura y propiedades electrónicas de una otras dos famílias de fulerenos endoédricos: la de los óxideos de escandio y la de los sulfuros de escandio.
Por último hemos estudiado las propiedades electroquímicas de una serie de fulerenos endoédricos con diferentes clústeres (capítulo 6). Los orbitales frontera y las propiedades redox de Sc3N@C80 son diferentes cuando son comparados con fulerenos endoédricos de metales más electro positivos (Gd e Y).We have extended the application of the general rule for the stabilization of nitride EMFs proposed by Campanera et al. to IPR carbon cages of dimensions up to C100. This simple rule, based on the formal transfer of six electrons from the cluster to the carbon cage, can be seen as an empirical rule that is able to predict the most abundant cage isomer for all the nitride EMFs known to date. Some EMF with M2 clusters, however, seem to escape this simple rule. We have proposed six large carbon cages (from C92 to C100) with sizeable (LUMO-4)–(LUMO-3) gaps and achievable energies as candidates for encapsulating metal nitride units or M2 clusters on condition that the formal six-electron transfer and other factors are accomplished. We have confirmed that the ionic model based on the formal transfer of four electrons from the encapsulated M2C2 carbide to the carbon cage is valid for the M2C2@C82 family. We have observed that the internal metal- carbide cluster is able to rotate inside the carbon cage. Using the aforesaid ionic model we have understood the higher stability of M2C2@C82 (C3v:8) when compared to carbide endohedrals with other IPR C82 isomers. The electrochemical properties for a series of EMFs have been studied theoretically. Analogously to the neutral M3N@Ih-C80 (M = Sc and Y) systems, rotation of the M3N unit inside the fullerene cage is predicted for the neutral, oxidized and reduced states of all the nitride EMFs with IPR cages studied through this work (from Sc3N@D5h-C80 to La3N@C96).
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García, Borràs Marc. "Structure and reactivity of endohedral (metallo)fullerenes." Doctoral thesis, Universitat de Girona, 2015. http://hdl.handle.net/10803/302920.
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It all started in 1985, when Kroto, Smalley and Curl discovered by serendipity a new carbon allotrope. They synthesized for the first time the C60 molecule, and named it as ”Buckminsterfullerene”, because of the similarity between its structure and the famous geodesic dome designed by the architect Richard Buckminster Fuller. An interesting type of fullerenes are the so-called endohedral (metallo)fullerenes, which are fullerenes containing atoms, small molecules or metallic clusters inside. A huge interest in this new class of molecules has been awakened mainly due to their potential applications in many different fields, for example in (bio)medicine as a magnetic resonance imaging contrast agents, or in photovoltaics as a new and more efficient dye sensitized solar cells. To that end, it is essential to know and understand their chemical structure and reactivity to ensure their use for (bio)medical purposes and to modify their properties to develop new fullerene-based technology devices or biomaterials. In this thesis the chemical structure and reactivity of endohedral (metallo)fullerenes is studied in detail using state-of-the-art computational toolsAl 1985, Kroto, Curl i Smalley van sintetitzar per primera vegada la molècula C60, i la van anomenar ”Buckminsterful·lerè” degut a la similitud entre la seva estructura i la famosa cúpula geodèsica dissenyada per l’arquitecte Richard Buckminster Fuller. Un tipus de ful·lerens molt interessants són els anomenats (metalo)ful·lerens endohèdrics, que són aquells que contenen àtoms, molècules petites o agregats metàl·lics encapusulats al seu interior. Des del seu descobriment s’ha despertat un enorme interès en aquestes molècules degut a les seves potencials aplicacions en camps molt diferents, com per exemple en (bio)medicina per al seu ús com a agents de contrast en imatge per ressonància magnètica, o en el camp de l’energia fotovoltaica per a la fabricació de noves cèl·lules solars. Per aquesta raó, és imprescindible conèixer i entendre la seva estructura i reactivitat química per tal de garantir el seu ús amb finalitats (bio)mèdiques i per modificar les seves propietats per desenvolupar nous (bio)materials basats en ful·lerens. En aquesta tesi, l’estructura química i la reactivitat dels (metalo)ful·lerens endohèdrics s’estudien en detall utilitzant les eines de la química computacional
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Naydenov, Boris N. "Encapsulation of endohedral fullerenes for quantum computing." [S.l.] : [s.n.], 2006. http://www.diss.fu-berlin.de/2006/659/index.html.
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Kanai, Mito. "Production, purification and characterization of incar-fullerenes." Thesis, Queen Mary, University of London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.415899.
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Morton, John J. L. "Electron spins in fullerenes as prospective qubits." Thesis, University of Oxford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.425947.
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Britz, David A. "Structure and bonding of fullerenes and nanotubes." Thesis, University of Oxford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.434859.
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Johansson, Olof Johan. "Angle-resolved femtosecond photoelectron spectroscopy of fullerenes." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/5038.
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An experimental apparatus has been constructed to investigate ionisation mechanisms of complex molecules and nanoparticles after femtosecond and/or picosecond laser excitation. The photoproducts are detected by time-of-flight mass spectrometry and velocity-map imaging (VMI) photoelectron spectroscopy. Test measurements on C60 and Xe have successfully reproduced previously published work indicating that the setup is working in a satisfactory manner. New detailed investigations of mass spectra and angle resolved photoelectron spectra (PES) have been carried out as a function of laser intensity, wavelength and pulse duration for C60 and C70, providing new insights into the electronic structure and ionisation mechanisms of these molecules. For 400 nm, 130 fs laser excitation, an isotropic contribution from thermally emitted electrons is found. A series of peaks are seen superimposed on the thermal background with binding energies in agreement with the recently discovered superatom molecular orbitals (SAMOs) of C60 [Feng et.al. Science 320 (2008) p. 359]. Furthermore, the angular dependence of the peak in the PES corresponding to the s-SAMO is in agreement with this assignment. To confirm the assignment of the other observed peaks it is concluded that the measured photoelectron angular distributions (PADs) need to be compared to calculated angular distributions. Measurements have also been made with the same wavelength but with a pulse duration of about 5 ps. Mass spectra, PES and PADs for these measurements show that the main ionisation mechanism for these laser conditions is delayed (thermionic) ionisation. For 800 nm, 130 and 180 fs laser excitation, thermally emitted electrons are observed. In contrast to the 400 nm measurements, the PADs show an asymmetry with higher apparent temperatures along the laser polarisation direction. Measurements were also made for longer pulse durations (1.0 – 3.8 ps). For pulse durations above 1 ps the asymmetry is gradually reduced while the delayed ionisation component in the mass spectrum increases with increasing pulse duration. The asymmetry is compared to calculations made assuming a field-assisted thermal electron emission. Similarly to the 400 nm experiments, a series of peaks are seen superimposed on the thermal background. PADs are presented for these peaks. PADs for peaks with the same binding energy as peaks seen in the 400 nm experiments follow the same trend. Isotropic PADs after ns laser excitation are also presented confirming delayed ionisation for these pulse durations.
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Henderson, Gordon George. "Femtosecond laser studies of fullerenes and nanotubes." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/7737.
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This work concerns the interaction of intense, ultrashort laser pulses with fullerenes and carbon nanotubes. This includes the excitation and ionisation dynamics of gas phase fullerenes and the response of carbon nanotubes to intense ultrashort laser pulses. When ionising C60 with laser pulses of duration between 50 fs up to a few hundred fs, the ionisation mechanism has been proposed to be thermal in nature, with the electronic subsystem ‘hot’ and the vibrational system ‘cold’ at the time of ionisation. Recent results show an anisotropy in the photoelectron angular distribution which may suggest more direct mechanisms at work. Velocity-Map Imaging photoelectron spectroscopy results are presented for the ionisation of C60 and C70 at various wavelengths, pulse durations and intensities and the results are compared to theoretical models. The results are described well by a thermal ionisation mechanism in which a significant number of electrons are emitted during the laser pulse. Electrons may gain a momentum ‘kick’ from the electric field of the laser which results in an anisotropy in the photoelectron angular distributions. Peaks are observed, superimposed on the thermal background, in the photoelectron kinetic energy spectra of fullerenes ionised by ultrashort laser pulses which were previously assigned as Rydberg peaks. Photoelectron angular distributions of these peaks are presented for C60 and C70 ionised with laser pulses of various wavelengths. The binding energies and anisotropy parameters fitted to the peaks suggest that they are due to the population and one-photon ionisation of superatom molecular orbitals (SAMOs). The results rule out a direct multiphoton population mechanism for these states and show many similarities with Rydberg fingerprint spectroscopy. The fusion of carbon nanotubes has been observed under high energy electron beams and fullerene molecules have been shown to fuse together after irradiation with ultrashort laser pulses. Results are presented for experiments where fusion of carbon nanotubes with ultrashort laser pulses was attempted. Thin carbon nanotube films are analysed via Raman spectroscopy after irradiation by single laser pulses. A number of low frequency radial breathing mode peaks were observed which suggest that fusion may have taken place at certain areas of the sample.
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Brisolla, Ravanello Bruno [Verfasser]. "Multicomponent reactions with fullerenes / Bruno Brisolla Ravanello." Halle, 2018. http://d-nb.info/1166140814/34.
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Grieco, William Joseph 1971. "Fullerenes and carbon nanostructures formation in flames." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/9654.
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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1999.Includes bibliographical references.
Fullerenes are molecules comprised entirely of sp2-bonded carbon atoms arranged in pentagonal and hexagonal rings to form a hollow, closed-cage structure. Fullerenes, such as C60 and C70, are single-shell molecules, while carbon nanostructures--a larger class of structures that includes fullerenes as a subset--typically contain many shells and hundreds or thousands of carbon atoms. C60 and C70, first discovered in 1985, were isolated macroscopically in 1991 from soot produced in laminar low pressure premixed benzene/oxygen/argon flames operated at fuel-rich conditions. Studies of these flames indicated that fullerene yields depend on adjustable parameters like temperature, pressure, atomic carbon/oxygen ratio, and residence time. In addition, high resolution transmission electron microscopy (HRTEM) showed that benzene flame soot also contains carbon nanostructures, including fullerene onions and nanotubes. Although some conditions under which fullerenes form in flames have been identified, little is known about the formation mechanisms of either fullerenes or carbon nanostructures. One possible mechanism involves a molecular weight growth process analogous to soot formation including 1) the stepwise addition of acetylene to curved precursor molecules and 2) the coagulation of aromatic precursor molecules, followed by bond rearrangement to form the closed-cage structure. Polycyclic aromatic hydrocarbons (P AH), which participate in soot nucleation and growth, are potential precursors in these mechanisms. Carbon nanostructures may form by a similar molecular weight growth process or by the rearrangement of carbon material in the condensed soot. Understanding these mechanisms and modeling the formation kinetics is important if combustion is to be used as a process for the synthesis of fullerenes and carbon nanostructures. Therefore, this work focuses on 1) developing a detailed understanding of the fullerenes formation mechanisms in premixed benzene/oxygen/argon flames by measuring concentration profiles for fullerenes (C60, C70, C76, C7s, and C84)., PAH, and light gas species and using the data to evaluate kinetic models consistent with proposed mechanisms and 2) understanding how carbon nanostructures form and evolve in premixed benzene/oxygen/ argon flames by using HRTEM to observe changes in soot and nanostructures with residence time in the flame. A laminar premixed benzene/oxygen/argon flat flame was operated at the following conditions: fuel equivalence ratio, 2.4 (atomic C/0 ratio, 0.96); cold gas velocity at the burner, 25 emfs; pressure, 40 torr; and fraction of argon in fuel mixture, 10 mol%. Concentrations of C6o, C10, C16, C1s, and C84 and 14 P AH were measured at different axial distances (residence times) in the flame, and an additional 16 PAH were identified without quantitation, by sampling condensible flame material through a quartz probe and analyzing the samples by high performance liquid chromatography (HPLC) and gas chromatography/mass spectrometry (GC/MS). The fullerenes concentration profiles show two regions of fullerenes formation and conswnption. The first region, at short residence times in the flame, coincides with the onset of soot formation and immediately follows the maximwn P AH concentration in this flame. The rate of conswnption of P AH is more than sufficient to account for the rate of formation offullerenes in this region of the flame, consistent with the view that reactive coagulation of P AH could be the dominant pathway for fullerenes formation. The second region, at longer residence times, shows significantly higher fullerenes concentrations and occurs in a part of the flame where the concentration of P AH is below the detection limit but where the concentration of acetylene remains high enough for acetylene to be the main reactant in this region of fullerenes formation. The observed rate of conswnption of acetylene through this region is more than sufficient to account for the observed rate of formation of fullerenes. The decrease in fullerenes concentration in the downstream part of both regions appears to be a result of competition between formation and conswnption reactions. Calculations show that neither oxidation nor pyrolysis alone can account for the observed conswnption of fullerenes, but reactions with soot may explain the observed conswnption. The fullerenes may be incorporated into the soot as surface growth species, and conswnption dominates when the concentration of PAH o; acetylene, which are the reactants for fullerenes formation, is lowered sufficiently. A study of changes in soot and carbon nanostructures with residence time in the same premixed benzene/oxygen/argon flame was conducted. Samples were taken by three different methods: scraping solids from surfaces inside the combustion chamber, collecting material from different vertical positions in the flame through a quartz probe, and collecting condensible material on an electron microscope grid at different vertical positions in the flame with a thermophoretic sampler. HRTEM imaging of all samples showed soot particles composed to some extent of amorphous and fullerenic carbon (i.e., curved layers, spiral shells, ,and fullerene molecule-sized closed-shell structures). Qualitative and quantitative analyses ofresidence time-resolved samples showed that the carbon layers increase in length and decrease in radius with increasing residence time in the flame and that the nwnber of closed-shell structures, possibly fullerene molecules, increases with residence time in the flame. This observation is consistent with fullerenes concentration increasing with residence time and with a consumption pathway in which fullerenes react with soot. Overall, the data suggest that the formation of amorphous and fullerenic carbon occurs in milliseconds, with the fullerenic carbon becoming more curved as a soot particle traverses the length of the flame. This formation process is consistent with the heterogeneous reaction of gas phase P AH or light hydrocarbons with carbon layers in the solid phase soot. Conversely, the formation of carbon nanostructures, such as nanotubes and fullerene onions, appears to require much longer residence times, perhaps seconds or minutes. This is consistent with the internal rearrangement of carbon layers in the solid phase which appears to occur while the soot is exposed to the high temperature flame environment for extended periods of time.
by William Joseph Grieco.
Ph.D.
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Puharic, Douglas. "The Face Consistency and Embeddability of Fullerenes." Bowling Green State University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1150909908.
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Aslanis, Efstathios. "Synthesis and characterisation of fullerene-based materials." Thesis, University of Sussex, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249094.
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Cullen, Sarah Louise. "Electron microscopy of carbon nanotubes." Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387605.
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