These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

Secondary ion emission under keV carbon cluster bombardment  

E-print Network

projectile for SIMS. The secondary ion yields (i.e., the number of secondary ions detected per projectile impact) from impacts of 10-26 keV C24H12+, C60+, gramicidin S+ and C60F40+ projectiles were examined to compare the effectiveness of the projectiles...

Locklear, Jay Edward

2006-10-30

2

Surface damage studies of ETFE polymer bombarded with low energy Si ions (?100 keV)  

NASA Astrophysics Data System (ADS)

Surface studies of ethylenetetrafluoroethylene (ETFE), bombarded with Si in a high-energy tandem Pelletron accelerator, have recently been reported. Si ion bombardment with a few MeV to a few hundred keV energies was shown to be sufficient to produce damage on ETFE film. We report here the use of a low energy implanter with Si ion energies lower than 100 keV, to induce changes on ETFE films. In order to determine the radiation damage, ETFE bombarded films were simulated with SRIM software and analyzed with optical absorption photometry (OAP), Raman and Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopy to show quantitatively the physical and chemical property changes. Carbonization occurs following higher dose implantation, and hydroperoxides were formed following dehydroflorination of the polymer.

Minamisawa, Renato Amaral; De Almeida, Adelaide; Budak, Satilmis; Abidzina, Volha; Ila, Daryush

2007-08-01

3

The repetitive flaking of inconel 625 by 100 keV helium ion bombardment  

NASA Astrophysics Data System (ADS)

Repetitive flaking of Inconel 625 occurs with ion bombardment doses of than 10 18 100 keV helium ions cm -2, with up to 39 exfoliations being observed after bombardment with 3 × 10 19 ions cm -2. The thickness of the flakes, measured by scanning electron microscopy, is some 30% greater than when measured by Rutherford backscattering (RBS) of 1.8 MeV helium ions. These RBS measurements compare well with the thickness of the remaining layers in the resultant craters and to the most probable range of the 100 keV helium. The area of the flakes is dictated by the grain boundaries, and when one flake is ejected, the adjacent grains are prevented from doing so since there now exists an escape route for the injected helium. A strong dose rate dependence is observed; decreasing the beam current from 640 ?A cm -2 to 64 ?A cm -2 results in a factor 20 fewer flakes being exfoliated (for the same total dose of 3 × 10 19 ions cm -2). Successive flakes decrease in area, suggesting that eventually a cratered, but stable, surface will result with the only erosion being by the much less effective mechanism of sputtering.

Whitton, J. L.; Chen, Hao Ming; Littmark, U.; Emmoth, B.

1981-05-01

4

Reflection electron energy loss spectroscopy of keV bombarded polystyrene at high ion fluences  

NASA Astrophysics Data System (ADS)

Reflection Electron Energy Loss Spectroscopy (REELS) is used to characterize the surface of thin films of polystyrene bombarded with keV ion beams in the fluence range 1 × 10 14-1 × 10 16 ions/cm 2. The characteristic features of REELS spectra of irradiated samples are in agreement with the formation of a hydrogenated amorphous carbon phase. The bulk plasmon shift and the inelastic scattering increase in the low-energy range of REELS spectra showed that the final structure is correlated to the total ion energy loss ( St) and to the predominant elastic or inelastic stopping regime. In particular, samples irradiated at a high St an predominant elastic regime show a higher film density and a higher valence electron density with respect to those irradiated at a low St and a predominant inelastic regime.

Marletta, Giovanni; Licciardello, Antonino; Calcagno, Lucia; Foti, Gaetano

1989-02-01

5

Study of the surface activation of ETFE by low energy (keV) Si and N bombardment  

NASA Astrophysics Data System (ADS)

The ethylenetetrafluoroethylene (ETFE) is a polymer formed by alternating ethylene and tetrafluoroethylene segments. It can be applied in the field of medical physics as intra venous catheters and as radiation dosimeters. The increasing application of polymeric materials in technological and scientific fields has motivated the use of surface treatments to modify the physical and chemical properties of polymer surfaces. When a material is exposed to ionizing radiation, it suffers damage leading to surface activation depending on the type, energy and intensity of the applied radiation. In order to determine the radiation damage and the surface activation mechanism ETFE films were bombarded with keV Si and N at various fluences. The bombarded film was also analyzed with optical absorption photospectrometry (OAP), Raman and Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopy showing quantitatively the chemical nature at the damage caused by the Si and N bombardment.

Parada, M. A.; de Almeida, A.; Muntele, C.; Muntele, I.; Delalez, N.; Ila, D.

2005-12-01

6

Fullerene ion irradiation to silicon  

NASA Astrophysics Data System (ADS)

Silicon has been irradiated by singly charged C 60 fullerene ions with an ion dose of up to 1 × 10 13 ions/cm 2 at room temperature in order to study the damage formation of cluster ion bombardment on solid surfaces. Singly and doubly charged fullerene ions and some daughter ions of fullerene were observed. Mass separation was accomplished by a 90° sector magnet. The maximum current of the mass-separated singly charged C 60 fullerene ion beam was about 10 nA. RBS (Rutherford backscattering spectrometry) channeling measurement of the Si(100) bombarded by 300 keV C 60 ions (i.e. 5.0 keV per carbon atom) shows a remarkable increase in the surface peak of the defects even at the low atomic dose of 6 × 10 14 atoms/cm 2. The C 60 fullerene ion beam irradiation produced many defects. This is one of the typical non-linear effects of cluster bombardment.

Tanomura, M.; Takeuchi, D.; Matsuo, J.; Takaoka, G. H.; Yamada, I.

1997-01-01

7

A statistical analysis of the lateral displacement of Si atoms in molecular dynamics simulations of successive bombardment with 20keV C60 projectiles  

Microsoft Academic Search

An important factor that determines the possible lateral resolution in sputter depth profiling experiments is ion induced lateral displacement of substrate atoms. Molecular dynamics (MD) simulations are performed to model the successive bombardment of Si with 20 keV C60 at normal incidence. A statistical analysis of the lateral displacement of atoms that originate from the topmost layer is presented and

K. D. Krantzman; E. L. Cook; A. Wucher; B. J. Garrison

2011-01-01

8

A statistical analysis of the lateral displacement of Si atoms in molecular dynamics simulations of successive bombardment with 20keV C 60 projectiles  

Microsoft Academic Search

An important factor that determines the possible lateral resolution in sputter depth profiling experiments is ion induced lateral displacement of substrate atoms. Molecular dynamics (MD) simulations are performed to model the successive bombardment of Si with 20keV C60 at normal incidence. A statistical analysis of the lateral displacement of atoms that originate from the topmost layer is presented and discussed.

K. D. Krantzman; E. L. Cook; A. Wucher; B. J. Garrison

2011-01-01

9

Spectral reflectance change and luminescence of selected salts during 2-10 KeV proton bombardment - Implications for Io  

NASA Technical Reports Server (NTRS)

Radiation damage and luminescence caused by magnetospheric charged particles have been suggested by several investigators as mechanisms that are capable of explaining some of the peculiar spectral/albedo features of Io. In the present paper, this possibility is pursued by measuring the UV-visual spectral reflectance and luminescent efficiency of several proposed Io surface constituents during 2 to 10 keV proton irradiation at room and low temperatures. The luminescence efficiencies of pure samples, studied in the laboratory, suggest that charged-particle induced luminescence from Io's surface might be observable by spacecraft such as Voyager when viewing Io's dark side.

Nelson, R. M.; Nash, D. B.

1979-01-01

10

The temperature effect on the glycine decomposition induced by 2 keV electron bombardment in space analog conditions  

NASA Astrophysics Data System (ADS)

Glycine is the simplest proteinaceous amino acid that has been extensively detected in carbonaceous meteorites and was recently observed in the cometary samples returned to Earth by NASA's Stardust spacecraft. In space, such species is exposed to several radiation fields at different temperatures. In aqueous solutions, this species appears mainly as zwitterionic glycine (+NH3CH2COO-) however, in solid phase, it may be found in amorphous or crystalline forms. Here, we present an experimental study on the destruction of two zwitterionic glycine crystals ( ?- and ?-form) at two different temperatures (300 K and 14 K) by 2 keV electrons in an attempt to test the behavior and stability of this molecular species in different space environments. The samples were analyzed in situ by Fourier transform infrared spectrometry at electron fluences. The experiments were carried out under ultra-high vacuum conditions at the Molecular Physics Laboratory at the Open University at Milton Keynes, UK. The dissociation cross section of glycine is approximately 5 times higher for the 14 K samples when compared to the 300 K samples. In contrast, no significant differences emerged between the dissociation cross sections of ?- and ?-forms of glycine for fixed temperature experiments. We therefore conclude that the destruction cross section is more heavily dependent on temperature than the phase of the condensed glycine material. This may be associated with the opening of additional reaction routes in the frozen samples involving the trapped daughter species (e.g. CO2 and CO). The half-life of studied samples extrapolated to space conditions shows that glycine molecules on the surface of interstellar grains has less survivability and they are highly sensitive to ambient radiations, however, they can survive extended period of time in the solar system like environments. Survivability increases by a factor of 5 if the samples are at 300 K when compared to low temperature experiments at 14 K and is independent of the crystalline structure. In addition, this survival would increase if the molecular species were protected by several layers of other molecular species as trapped in comet mantles or embedded within regolith in asteroids/lunar surfaces. The understanding of the excitation and dissociation processes of organic compounds in space simulation is highly required to put constrains in the puzzle over the origin of life in the primitive Earth.

Pilling, Sergio; Nair, Binu G.; Escobar, Antonio; Fraser, Helen; Mason, Nigel

2014-03-01

11

A statistical analysis of the lateral displacement of Si atoms in molecular dynamics simulations of successive bombardment with 20-keV C 60 projectiles  

NASA Astrophysics Data System (ADS)

An important factor that determines the possible lateral resolution in sputter depth profiling experiments is ion induced lateral displacement of substrate atoms. Molecular dynamics (MD) simulations are performed to model the successive bombardment of Si with 20 keV C60 at normal incidence. A statistical analysis of the lateral displacement of atoms that originate from the topmost layer is presented and discussed. From these results, it is determined that the motion is isotropic and can be described mathematically by a simple diffusion equation. A “diffusion coefficient” for lateral displacement is determined to be 3.5 Å2/impact. This value can be used to calculate the average lateral distance moved as a function of the number of impacts. The maximum distance an atom may move is limited by the time that it remains on the surface before it is sputtered. After 800 impacts, 99% of atoms from the topmost layer have been removed, and the average distance moved by these atoms is predicted to be 100 Å. Although the behavior can be described mathematically by the diffusion equation, the behavior of the atoms is different than what is thought of as normal diffusion. Atoms are displaced a large distance due to infrequent large hops.

Krantzman, K. D.; Cook, E. L.; Wucher, A.; Garrison, B. J.

2011-07-01

12

Cosmic Bombardment.  

National Technical Information Service (NTIS)

Throughout its history, the earth has been constantly bombarded by interplanetary bodies. In the maelstrom of the earth Solar System, such collisions created our planet and then fed its growth. With time, the rate of such collisions has dropped enormously...

R. A. Hyde

1984-01-01

13

The Stability of Cosmic Fullerenes and Fullerenic Aggregates  

NASA Astrophysics Data System (ADS)

Establishing the stability of cosmic fullerenes and fullerenic aggregates is extremely relevant for a variety of reasons. For instance, the emission features of C60 and C70 fall in the same spectral region as the Un-identified InfraRed (UIR) bands, which they could contribute to. To be able to contribute to the UIR emission, however, fullerenes must be able to survive long enough against the destruction mechanisms operating in the interstellar medium. In this study we focus on the effects of collisional processing, i.e., the bombardment by energetic ions and electrons. A recent experimental/theoretical study has shown that ion collisions with C60 clusters result in the dissociation of the cluster with the simultaneous formation of covalent fullerene dimers, which could play a role as DIBs carriers. We present here our first results about the collisional processing of C60 molecules and clusters by H, He and C ions in interstellar shocks. We have adapted the models that have previously been developed to successfully treat the collisional processing of PAHs in space. The nature of the interaction and the similarities between PAHs and fullerenes make this approach appropriate. In addition, our study shows that the formation of covalent dimers following ion collisions with C60 clusters is compatible with the astrophysical conditions under consideration.

Micelotta, E. R.; Cami, J.; Peeters, E.; Zettergren, H.; Schmidt, H. T.; Cederquist, H.; Jones, A. P.; Tielens, A. G. G. M.

2014-02-01

14

Friction model to describe cluster bombardment  

Microsoft Academic Search

Short time molecular dynamics simulations were performed to model C60 and Au3 bombardment of an amorphous water sample in the projectile energy range of 5–120keV. A previously proposed friction model has been applied to describe the fundamental motion of a projectile during cluster bombardment of a solid. This simple analytical model uses a definition of friction on a single particle

Kathleen E. Ryan; Michael F. Russo; Edward J. Smiley; Zbigniew Postawa; Barbara J. Garrison

2008-01-01

15

Friction model to describe cluster bombardment  

NASA Astrophysics Data System (ADS)

Short time molecular dynamics simulations were performed to model C 60 and Au 3 bombardment of an amorphous water sample in the projectile energy range of 5-120 keV. A previously proposed friction model has been applied to describe the fundamental motion of a projectile during cluster bombardment of a solid. This simple analytical model uses a definition of friction on a single particle to describe the cluster movement through a medium. Although the mathematics of the friction model vary among systems, the projectile motion and energy deposition of a single particle into the sample as well as the reactive environment created is close to that of C 60 bombardment.

Ryan, Kathleen E.; Russo, Michael F.; Smiley, Edward J.; Postawa, Zbigniew; Garrison, Barbara J.

2008-12-01

16

Fullerene Machines  

NASA Technical Reports Server (NTRS)

Recent computational efforts at NASA Ames Research Center and computation and experiment elsewhere suggest that a nanotechnology of machine phase functionalized fullerenes may be synthetically accessible and of great interest. We have computationally demonstrated that molecular gears fashioned from (14,0) single-walled carbon nanotubes and benzyne teeth should operate well at 50-100 gigahertz. Preliminary results suggest that these gears can be cooled by a helium atmosphere and a laser motor can power fullerene gears if a positive and negative charge have been added to form a dipole. In addition, we have unproven concepts based on experimental and computational evidence for support structures, computer control, a system architecture, a variety of components, and manufacture. Combining fullerene machines with the remarkable mechanical properties of carbon nanotubes, there is some reason to believe that a focused effort to develop fullerene nanotechnology could yield materials with tremendous properties.

Globus, Al; Saini, Subhash

1998-01-01

17

Surface layer modification of ion bombarded HDPE  

Microsoft Academic Search

Press-moulded, high density polyethylene (HDPE) samples were subjected to ion bombardment and effects of the modification studied. He+ ions of energy 100 keV or Ar+ ions of energy 130 keV were applied in the range of dose 1–30×1015\\/cm2 or 1–100×1014\\/cm2, respectively. This paper has been focused on structural changes of the surface layer. The consequences of the modification were studied

D. Bielinski; P. Lipinski; L. Slusarski; J. Grams; T. Paryjczak; J. Jagielski; A. Turos; N. K. Madi

2004-01-01

18

Vacuum 82 (2008) 11201123 Applications of fullerene beams in analysis of thin layers  

E-print Network

computer simulations used to model particle bombardment are described elsewhere [5]. Briefly, the motion computer simulations have been employed to model ejection of particles from Ag{1 1 1} metal substrate and thin benzene overlayer bombarded by fullerene cluster projectiles. The sputtering yields are analyzed

Zbigniew, Postawa

19

Fullerene Machines  

NASA Technical Reports Server (NTRS)

Fullerenes possess remarkable properties and many investigators have examined the mechanical, electronic and other characteristics of carbon SP2 systems in some detail. In addition, C-60 can be functionalized with many classes of molecular fragments and we may expect the caps of carbon nanotubes to have a similar chemistry. Finally, carbon nanotubes have been attached to t he end of scanning probe microscope (Spill) tips. Spills can be manipulated with sub-angstrom accuracy. Together, these investigations suggest that complex molecular machines made of fullerenes may someday be created and manipulated with very high accuracy. We have studied some such systems computationally (primarily functionalized carbon nanotube gears and computer components). If such machines can be combined appropriately, a class of materials may be created that can sense their environment, calculate a response, and act. The implications of such hypothetical materials are substantial.

Globus, Al; Saini, Subhash (Technical Monitor)

1998-01-01

20

Switching Molecular Orientation of Individual Fullerene at Room Temperature  

PubMed Central

Reversible molecular switches with molecular orientation as the information carrier have been achieved on individual fullerene molecules adsorbed on Si (111) surface at room temperature. Scanning tunneling microscopy imaging directly demonstrates that the orientation of individual fullerene with an adsorption geometry of 5-6 bond is rotated by integral times as 30 degree after a pulse bias is applied between the STM tip and the molecule. Dependences of the molecular rotation probability on the voltage and the process of applied bias reveal that the rotation of a fullerene molecule takes place in two successive steps: the bonding between the fullerene and the Si surface is firstly weakened via electronic excitation and then low energy electron bombardment causes the molecule to rotate by certain degree. PMID:24162548

Liu, Lacheng; Liu, Shuyi; Chen, Xiu; Li, Chao; Ling, Jie; Liu, Xiaoqing; Cai, Yingxiang; Wang, Li

2013-01-01

21

Combustion synthesis of fullerenes and fullerenic nanostructures  

Microsoft Academic Search

Samples of condensable material collected from low-pressure premixed and diffusion benzene\\/oxygen\\/argon flames were analyzed chemically to determine fullerene yield and by high-resolution transmission electron microscopy to characterize the fullerenic material on and within the soot particles. Results show that fullerene formation is sensitive to changes in operating conditions, such as fuel\\/oxygen ratio, chamber pressure, and inert gas dilution, and that

Anish Goel; Peter Hebgen; John B Vander Sande; Jack B Howard

2002-01-01

22

Conversion of fullerenes to diamond  

DOEpatents

A method of forming synthetic diamond on a substrate. The method involves providing a substrate surface covered with a fullerene or diamond coating, positioning a fullerene in an ionization source, creating a fullerene vapor, ionizing fullerene molecules, accelerating the fullerene ions to energies above 250 eV to form a fullerene ion beam, impinging the fullerene ion beam on the substrate surface and continuing these steps to obtain a diamond film thickness on the substrate.

Gruen, Dieter M. (1324 59th St., Downers Grove, IL 60515)

1994-01-01

23

Fullerene nanowhiskers and related fullerene nanomaterials  

NASA Astrophysics Data System (ADS)

Since the discovery of C60 nanowhiskers in a colloidal solution of PZT in 2001, various low-dimensional fullerene nanomaterials such as fullerene nanotubes and fullerene nanosheets have been synthesized by the liquid-liquid interfacial precipitation method (LLIP method) as well as the C60 and C70 nanowhiskers. The LLIP method is an excellent process to synthesize the quasi one-dimensional fullerene nanomaterials. This paper first reviews the typical fullerene nano and micro materials that have been prepared by the LLIP method and then show that the LLIP method is also applicable to the synthesis of composite C60 nano and micro whiskers containing wide compositions of C60 derivative molecules.

Miyazawa, K.; Kato, R.; Saito, K.; Kizuka, T.; Mashino, T.; Nakamura, S.

2009-04-01

24

Fullerene Nanogears  

NASA Technical Reports Server (NTRS)

The Numerical Aerospace Simulation Systems Division (NAS) of the NASA Ames Research Center, Moffett Field, California is conducting research into molecular-sized devices known as Nanotechnology. This photograph depicts two 'Fullerene Nano-gears' with multiple teeth. The hope is that one day, products can be constructed made of thousands of tiny machines that could self-repair and adapt to the environment in which they exist. Researchers have simulated attaching benzyne molecules to the outside of a nanotube to form gear teeth. Nanotubes are molecular-sized pipes made of carbon atoms. To 'drive' the gears, the supercomputer simulated a laser that served as a motor. The laser creates an electric field around the nanotube. A positively charged atom is placed on one side of the nanotube, and a negatively charged atom on the other side. The electric field drags the nanotube around like a shaft turning. Jie Han, Al Globus, Richard Jaffe and Glenn Deardorff are the authors of a technical paper detailing this technology which appears in The Journal of Nanotechnology.

1997-01-01

25

Fullerenes in Allende Meteorite  

NASA Technical Reports Server (NTRS)

The detection of fullerenes in deposits from meteor impacts has led to renewed interest in the possibility that fullerenes are present in meteorites. Although fullerenes have not previously been detected in the Murchison and Allende meteorites, the Allende meteorite is known to contain several well-ordered graphite particles which are remarkably similar in size and appearance to the fullerene-related structures carbon onions and nanotubes. We report that fullerenes are in fact present in trace amounts in the Allende meteorite. In addition to fullerenes, we detected many polycyclic aromatic hydrocarbons (PAHs) in the Allende meteorite, consistent with previous reports. In particular, we detected benzofluoranthene and corannulene (C20H10), five-membered ring structures which have been proposed as precursors to the formation of fullerene synthesis, perhaps within circumstellar envelopes or other sites in the interstellar medium.

Becker, L.; Bada, J. L.; Winans, R. E.; Bunch, T. E.

1994-01-01

26

Combustion method for producing fullerenes  

DOEpatents

A method for synthesizing fullerenes in flames is provided. Fullerenes are prepared by burning carbon-containing compounds in a flame and collecting the condensibles. The condensibles contain the desired fullerenes. Fullerene yields can be optimized and fullerene composition can be selectively varied. Fullerene yields and compositions are determined by selectively controlling flame conditions and parameters such as C/O ratio, pressure, temperature, residence time, diluent concentration and gas velocity.

Howard, Jack B. (Winchester, MA); McKinnon, J. Thomas (Boulder, CO)

1993-01-01

27

Combustion method for producing fullerenes  

DOEpatents

A method for synthesizing fullerenes in flames is provided. Fullerenes are prepared by burning carbon-containing compounds in a flame and collecting the condensable. The condensable contain the desired fullerenes. Fullerene yields can be optimized and fullerene composition can be selectively varied. Fullerene yields and compositions are determined by selectively controlling flame conditions and parameters such as C/O ratio, pressure, temperature, residence time, diluent concentration and gas velocity. 4 figures.

Howard, J.B.; McKinnon, J.T.

1993-12-28

28

Interstellar and circumstellar fullerenes  

E-print Network

Fullerenes are a particularly stable class of carbon molecules in the shape of a hollow sphere or ellipsoid that might be formed in the outflows of carbon stars. Once injected into the interstellar medium (ISM), these stable species survive and are thus likely to be widespread in the Galaxy where they contribute to interstellar extinction, heating processes, and complex chemical reactions. In recent years, the fullerene species C60 (and to a lesser extent C70) have been detected in a wide variety of circumstellar and interstellar environments showing that when conditions are favourable, fullerenes are formed efficiently. Fullerenes are the first and only large aromatics firmly identified in space. The detection of fullerenes is thus crucial to provide clues as to the key chemical pathways leading to the formation of large complex organic molecules in space, and offers a great diagnostic tool to describe the environment in which they reside. Since fullerenes share many physical properties with PAHs, understand...

Bernard-Salas, J; Jones, A P; Peeters, E; Micelotta, E R; Otsuka, M; Sloan, G C; Kemper, F; Groenewegen, M

2014-01-01

29

Combustion synthesis of fullerenes and fullerenic nanostructures  

E-print Network

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 C?? and C??, are single-shell ...

Goel, Anish

2002-01-01

30

The Generation of Fullerenes  

E-print Network

We describe an efficient new algorithm for the generation of fullerenes. Our implementation of this algorithm is more than 3.5 times faster than the previously fastest generator for fullerenes -- fullgen -- and the first program since fullgen to be useful for more than 100 vertices. We also note a programming error in fullgen that caused problems for 136 or more vertices. We tabulate the numbers of fullerenes and IPR fullerenes up to 400 vertices. We also verify up to 316 vertices a conjecture of Barnett that cubic planar graphs with maximum face size 6 are hamiltonian.

Brinkmann, Gunnar; McKay, Brendan D

2012-01-01

31

Covalent Fullerene Chemistry  

Microsoft Academic Search

The covalent functionalization of C60 has developed vigorously over the past 5 years. Several methods are now available for the formation of C60 monoadducts. Regioselective formation of multiple adducts has allowed study of the changes in chemical and physical properties that occur when the conjugated fullerene chromophore is reduced during an increase in functionalization. The systematic development of covalent fullerene

Francois Diederich; Carlo Thilgen

1996-01-01

32

Interstellar and Circumstellar Fullerenes  

NASA Astrophysics Data System (ADS)

Fullerenes are a particularly stable class of carbon molecules in the shape of a hollow sphere or ellipsoid that might be formed in the outflows of carbon stars. Once injected into the interstellar medium (ISM), these stable species survive and are thus likely to be widespread in the Galaxy where they contribute to interstellar extinction, heating processes, and complex chemical reactions. In recent years, the fullerene species C60 (and to a lesser extent C70 ) have been detected in a wide variety of circumstellar and interstellar environments showing that when conditions are favourable, fullerenes are formed efficiently. Fullerenes are the first and only large aromatics firmly identified in space. The detection of fullerenes is thus crucial to provide clues as to the key chemical pathways leading to the formation of large complex organic molecules in space, and offers a great diagnostic tool to describe the environment in which they reside. Since fullerenes share many physical properties with PAHs, understanding how fullerenes form, evolve and respond to their physical environment will yield important insights into one of the largest reservoirs of organic material in space. In spite of all these detections, many questions remain about precisely which members of the fullerene family are present in space, how they form and evolve, and what their excitation mechanism is. We present here an overview of what we know from astronomical observations of fullerenes in these different environments, and discuss current thinking about the excitation process. We highlight the various formation mechanisms that have been proposed, discuss the physical conditions conducive to the formation and/or detection of fullerenes in carbon stars, and their possible connection to PAHs, HACs and other dust features.

Bernard-Salas, J.; Cami, J.; Jones, A.; Peeters, E.; Micelotta, E.; Otsuka, M.; Sloan, G. C.; Kemper, C.; Groenewegen, M.

33

Process for fullerene functionalization  

DOEpatents

Di-addended and tetra-addended Buckminster fullerenes are synthesized through the use of novel organoborane intermediates. The C.sub.60, C.sub.70, or higher fullerene is reacted with a borane such as BH.sub.3 in a solvent such as toluene to form an organoborane intermediate. Reaction of the organoborane such as hydrolysis with water or alcohol results in the product di-addended and tetra-addended fullerene in up to 30% yields. Dihydrofullerenes and tetrahydrofullerenes are produced by the process of the invention.

Cahill, Paul A. (Albuquerque, NM); Henderson, Craig C. (Dublin, CA)

1995-01-01

34

Covalent fullerene chemistry  

Microsoft Academic Search

A brief introduction to the reactivity principles governing the covalent chemistry of fullerenes is provided. The combination of synthetic fullerene and acetylene chemistry gives access to a family of novel molecular carbon allotropes with interesting physical properties. A versatile strategy for the regioselective preparation of specific bis- through hexakis-adducts of C6o based on the tether-directed remote functionalization was developed. Large

FranGois Diederich

1997-01-01

35

Are fullerene tubules metallic  

Microsoft Academic Search

We have calculated the electronic structure of a fullerene tubule using a first-principles, self-consistent, all-electron Gaussian-orbital based local-density-functional approach. Extending these results to a model containing an electron-lattice interaction, we estimate that the mean-field transition temperature from a Peierls-distorted regime to a high-temperature metallic regime should be well below room temperature. Such fullerene tubules should have the advantages (compared to

J. W. Mintmire; B. I. Dunlap; C. T. White

1992-01-01

36

Fast Atom Bombardment Mass Spectrometry.  

ERIC Educational Resources Information Center

Discusses reactions and characteristics of fast atom bombardment (FAB) mass spectroscopy in which samples are ionized in a condensed state by bombardment with xenon or argon atoms, yielding positive/negative secondary ions. Includes applications of FAB to structural problems and considers future developments using the technique. (Author/JN)

Rinehart, Kenneth L., Jr.

1982-01-01

37

Hall Mobility versus Bombardment Energy and Temperature in an Ion Bombarded Polymer  

NASA Astrophysics Data System (ADS)

Ion bombardment dramatically increases the surface conductivity (?) of many polymers. Increases in crosslink density are expected to produce increases in the charge carrier mobility and ? because the formation of crosslinks creates a percolation network. We have measured the Hall mobility (?) in poly(benzimidazobenzphenanthroline) (BBL), a fully conjugated ladder polymer, bombarded at energies (E_B) 200--700 keV and temperatures (T_B) 50--450^circC. Our results show that higher EB and TB are more effective in creating a highly crosslinked network of bonds, as manifest in significantly increased ? and ? in these samples. The conductivity and Hall mobility were also measured as a function of temperature in some representative samples. The most conducting samples are like disordered metals with ?(T) increasing weakly with T while ?(T) decreases very slightly. The change in temperature dependence of ?(T) and ?(T) for samples bombarded at different EB and TB will be discussed in the context of a possible metal insulator transition.

Long, V. C.; Washburn, S.; Chen, X. L.; Jenekhe, S. A.

1996-03-01

38

Induction of antioxidant enzyme activity and lipid peroxidation level in ion-beam-bombarded rice seeds  

NASA Astrophysics Data System (ADS)

Low-energy ion beam bombardment has been used to mutate a wide variety of plant species. To explore the indirect effects of low-energy ion beam on biological damage due to the free radical production in plant cells, the increase in antioxidant enzyme activities and lipid peroxidation level was investigated in ion-bombarded rice seeds. Local rice seeds were bombarded with nitrogen or argon ion beams at energies of 29-60 keV and ion fluences of 1 × 1016 ions cm-2. The activities of the antioxidant enzymes; superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), glutathione reductase (GR), glutathione S-transferase (GST) and lipid peroxidation level were assayed in the germinated rice seeds after ion bombardment. The results showed most of the enzyme activities and lipid peroxidation levels in both the argon and nitrogen bombarded samples were higher than those in the natural control. N-ion bombardment could induce higher levels of antioxidant enzyme activities in the rice samples than the Ar-ion bombardment. Additional effects due to the vacuum condition were found to affect activities of some antioxidant enzymes and lipid peroxidation level. This study demonstrates that ion beam bombardment and vacuum condition could induce the antioxidant enzyme activity and lipid peroxidation level which might be due to free radical production in the bombarded rice seeds.

Semsang, Nuananong; Yu, LiangDeng

2013-07-01

39

Extraterrestrial Helium Trapped in Fullerenes in the Sudbury Impact Structure  

NASA Technical Reports Server (NTRS)

Fullerenes (C60 and C70) in the Sudbury impact structure contain trapped helium with a He-3/He-4 ratio of 5.5 x 10(exp -4) to 5.9 x 10(exp -4). The He-3/He-4 ratio exceeds the accepted solar wind value by 20 to 30 percent and is higher by an order of magnitude than the maximum reported mantle value. Terrestrial nuclear reactions or cosmic-ray bombardment are not sufficient to generate such a high ratio. The He-3/He-4 ratios in the Sudbury fullerenes are similar to those found in meteorites and in some interplanetary dust particles. The implication is that the helium within the C60 molecules at Sudbury is of extraterrestrial origin.

Becker, Luann; Poreda, Robert J.; Bada, Jeffrey L.

1996-01-01

40

The chemistry of fullerenes  

Microsoft Academic Search

Initially envisaged as rather unreactive, aromatic-like molecules, the fullerenes instead undergo a wide variety of reactions characteristic of alkenes. The many derivatives of C60, and the few of C70, that have now been reported offer new directions for organic chemistry.

Roger Taylor; David R. M. Walton

1993-01-01

41

Polymers containing fullerene or carbon nanotube structures  

Microsoft Academic Search

This review deals with recent progress in studies of polymeric covalent and noncovalent modifications of fullerenes (mainly C60) and carbon nanotubes (CNTs), and their applications. By using functional polymers to react with fullerenes, or synthesizing polymers in the presence of fullerenes, various kinds of polymeric fullerenes can be prepared: side-chain polymers, main-chain polymers, dendritic fullerenes, star-shaped polymers, fullerene end-capped polymers,

Changchun Wang; Zhi-Xin Guo; Shoukuan Fu; Wei Wu; Daoben Zhu

2004-01-01

42

Depth resolution improvement in secondary ion mass spectrometry analysis using metal cluster complex ion bombardment  

SciTech Connect

Secondary ion mass spectrometry analyses were carried out using a metal cluster complex ion of Ir{sub 4}(CO){sub 7}{sup +} as a primary ion beam. Depth resolution was evaluated as a function of primary ion species, energy, and incident angle. The depth resolution obtained using cluster ion bombardment was considerably better than that obtained by oxygen ion bombardment under the same experimental condition due to reduction of atomic mixing in the depth. The authors obtained a depth resolution of {approx}1 nm under 5 keV, 45 deg. condition. Depth resolution was degraded by ion-bombardment-induced surface roughness at 5 keV with higher incident angles.

Tomita, M.; Kinno, T.; Koike, M.; Tanaka, H.; Takeno, S.; Fujiwara, Y.; Kondou, K.; Teranishi, Y.; Nonaka, H.; Fujimoto, T.; Kurokawa, A.; Ichimura, S. [Corporate Research and Development Center, Toshiba Corporation, 8 Shinsugita-cho, Isogo-ku, Yokohama 235-8522 (Japan); National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 2, 1-1-1 Umezono, Tsukuba-shi, Ibaraki-ken 305-8568 (Japan)

2006-07-31

43

Computed Molecular Depth Profile for C60 Bombardment of a Molecular solid  

E-print Network

dynamics (MD) simulations have been performed for 10 keV C60 bombardment of an octane molecular solid-SSM) to understand the nature of molecular motions and to predict a depth profile of a -layer. The octane system has projectile relative to the cohesive energy of the molecular solid and the bond strengths within individual

Zbigniew, Postawa

44

Internal energy of molecules ejected due to energetic C60 bombardment  

PubMed Central

The early stages of C60 bombardment of octane and octatetraene crystals are modeled using molecular dynamics simulations with incident energies of 5-20 keV. Using the AIREBO potential, which allows for chemical reactions in hydrocarbon molecules, we are able to investigate how the projectile energy is partitioned into changes in potential and kinetic energy as well as how much energy flows into reacted molecules and internal energy. Several animations have been included to illustrate the bombardment process. The results show that the material near the edge of the crater can be ejected with low internal energies and that ejected molecules maintain their internal energies in the plume, in contrast to a collisional cooling mechanism previously proposed. In addition, a single C60 bombardment was able to create many free and reacted H atoms which may aid in the ionization of molecules upon subsequent bombardment events. PMID:19228010

Garrison, Barbara J.; Postawa, Zbigniew; Ryan, Kathleen E.; Vickerman, John C.; Webb, Roger P.; Winograd, Nicholas

2009-01-01

45

Fullerenes Buckminster Fullerenes ("Buckyballs") have fascinated chemists since the original discovery of C60, leading  

E-print Network

Fullerenes Buckminster Fullerenes ("Buckyballs") have fascinated chemists since the original fullerenes of various sizes have since been observed, the theoretically smallest fullerene, C28, has until Fourier Transform Ion Cyclotron Resonance Mass Spectrometer Citation: The Smallest Stable Fullerene: M@C28

Weston, Ken

46

Fullerenes with metals inside  

Microsoft Academic Search

Fullerenes with a single lanthanum atom trapped on the inside of the carbon cage were produced by laser vaporization of a lanthanum oxide\\/graphite composite rod in a flow of argon gas at 1,200 C. When sublimed wit Cââ and Cââ, they formed an air-stable film containing principally LaCââ, LaCââ, LaCââ, and LaCââ. When dissolved in toluene and exposed to air,

Yan Chai; Ting Guo; Changming Jin; Robert E. Haufler; L. P. Felipe Chibante; Jan Fure; Lihong Wang; J. Michael Alford; Richard E. Smalley

1991-01-01

47

Fullerenes under high pressures  

Microsoft Academic Search

This paper reviews the properties and phases of fullerenes and their derivatives and compounds under high pressures. For obvious reasons most of the paper deals with C60 but the materials reviewed also include C70, simple derivatives of C60, carbon nanotubes, and intercalation compounds of C60 with both acceptors and donors, mainly alkali metals. After a brief overview of high-pressure techniques

B. Sundqvist

1999-01-01

48

Synthesis of fullerenes from coal  

Microsoft Academic Search

Fullerenes have been synthesized from a low ash Illinois coal (IBC 108) and the yields are comparable to that obtained using graphite under similar conditions. The purpose of this work was to identify inexpensive sources of carbon to substitute graphite used commonly for fullerene synthesis. The as-obtained coal was demineralized, compacted into electrodes and carbonized at 850°C in an inert

Alan Weston; Mahesh Murthy; Shashi Lalvani

1995-01-01

49

Chiral fullerenes from asymmetric catalysis.  

PubMed

Fullerenes are among the most studied molecules during the last three decades, and therefore, a huge number of chemical reactions have been tested on these new carbon allotropes. However, the aim of most of the reactions carried out on fullerenes has been to afford chemically modified fullerenes that are soluble in organic solvents or even water in the search for different mechanical, optical, or electronic properties. Therefore, although a lot of effort has been devoted to the chemical functionalization of these molecular allotropes of carbon, important aspects in the chemistry of fullerenes have not been properly addressed. In particular, the synthesis of chiral fullerenes at will in an efficient manner using asymmetric catalysis has not been previously addressed in fullerene science. Thus, despite the fact that the chirality of fullerenes has always been considered a fundamental issue, the lack of a general stereoselective synthetic methodology has restricted the use of enantiopure fullerene derivatives, which have usually been obtained only after highly expensive HPLC isolation on specific chiral columns or prepared from a pool of chiral starting materials. In this Account, we describe the first stereodivergent catalytic enantioselective syntheses in fullerene science, which have allowed the highly efficient synthesis of enantiomerically pure derivatives with total control of the stereochemical result using metallic catalysts and/or organocatalysts under very mild conditions. Density functional theory calculations strongly support the experimental findings for the assignment of the absolute configuration of the new stereocenters, which has also been ascertained by application of the sector rule and single-crystal X-ray diffraction. The use of the curved double bond of fullerene cages as a two-?-electron component in a variety of stereoselective cycloaddition reactions represents a challenging goal considering that, in contrast to most of the substituted olefins used in these reactions, pristine fullerene is a noncoordinating dipolarophile. The aforementioned features make the study of stereoselective 1,3-dipolar cycloadditions onto fullerenes a unique scenario to shed light onto important mechanistic aspects. On the other hand, the availability of achiral starting materials as well as the use of nonexpensive asymmetric catalysts should provide access to chiral fullerenes and their further application in a variety of different fields. In this regard, in addition to biomedical applications, chiral fullerenes are of interest in less-studied areas such as materials science, organic electronics, and nanoscience, where control of the order and morphology at the nanometer scale are critical issues for achieving better device efficiencies. PMID:25080165

Maroto, Enrique E; Izquierdo, Marta; Reboredo, Silvia; Marco-Martínez, Juan; Filippone, Salvatore; Martín, Nazario

2014-08-19

50

Ion bombardment in RF photoguns  

SciTech Connect

A linac-ring eRHIC design requires a high-intensity CW source of polarized electrons. An SRF gun is viable option that can deliver the required beam. Numerical simulations presented elsewhere have shown that ion bombardment can occur in an RF gun, possibly limiting lifetime of a NEA GaAs cathode. In this paper, we analytically solve the equations of motion of ions in an RF gun using the ponderomotive potential of the Rf field. We apply the method to the BNL 1/2-cell SRF photogun and demonstrate that a significant portion of ions produced in the gun can reach the cathode if no special precautions are taken. Also, the paper discusses possible mitigation techniques that can reduce the rate of ion bombardment.

Pozdeyev,E.; Kayran, D.; Litvinenko, V. N.

2009-05-04

51

Cereal transformation through particle bombardment  

NASA Technical Reports Server (NTRS)

The review focuses on experiments that lead to stable transformation in cereals using microprojectile bombardment. The discussion of biological factors that affect transformation examines target tissues and vector systems for gene transfer. The vector systems include reporter genes, selectable markers, genes of agronomic interest, and vector constructions. Other topics include physical parameters that affect DNA delivery, selection of stably transformed cells and plant regeneration, and analysis of gene expression and transmission to the progeny.

Casas, A. M.; Kononowicz, A. K.; Bressan, R. A.; Hasegawa, P. M.; Mitchell, C. A. (Principal Investigator)

1995-01-01

52

Metal ion bombardment of onion skin cell wall  

SciTech Connect

Ion bombardment of living cellular material is a novel subfield of ion beam surface modification that is receiving growing attention from the ion beam and biological communities. Although it has been demonstrated that the technique is sound, in that an adequate fraction of the living cells can survive both the vacuum environment and energetic ion bombardment, there remains much uncertainty about the process details. Here we report on our observations of onion skin cells that were subjected to ion implantation, and propose some possible physical models that tend to support the experimental results. The ion beams used were metallic (Mg, Ti, Fe, Ni, Cu), mean ion energy was typically 30keV, and the implantation fluence was in the range 1014 1016 ions/cm2. The cells were viewed using Atomic Force Microscopy, revealing the formation of microcrater-like structures due to ion bombardment. The implantation depth profile was measured with Rutherford backscattering spectrometry and compared to the results of the TRIM, T-DYN and PROFILE computer codes.

Sangyuenyongpipat, S.; Vilaithong, T.; Yu, L.D.; Verdaguer, A.; Ratera, I.; Ogletree, D.F.; Monteiro, O.R.; Brown, I.G.

2004-05-10

53

On the sextet polynomial of fullerenes Jean-Sebastien Sereni  

E-print Network

with no adjacent pentagons is said to satisfy the isolated pentagon rule (IPR), and is called an IPR fullerene. The buckminsterfullerene is the smallest IPR fullerene, and all the most stable fullerenes are IPR fullerenes. Since

Paris-Sud XI, Université de

54

Omni-conducting fullerenes  

NASA Astrophysics Data System (ADS)

Within the graph-theoretical SPP (Source-and-Sink Potential) model, a strong omni-conductor can be defined as a molecular graph that is predicted to conduct at the Fermi level, no matter how it is connected by single-atom contacts to the wires. Exhaustive search (n ? 70 for general isomers; n ? 140 for isolated-pentagon isomers) shows that nearly all fullerene isomers Cn in the chemical size range are strong omni-conductors. The isolated-pentagon isomer of C60 is a strong omniconductor, whereas the isolated-pentagon isomer of C70, which has a non-bonding LUMO, has some insulating pairs of connections.

Fowler, P. W.; Pickup, B. T.; Todorova, T. Z.; De Los Reyes, R.; Sciriha, I.

2013-05-01

55

Effects of low and high energy ion bombardment on ETFE polymer  

NASA Astrophysics Data System (ADS)

The polymer ethylenetetrafluoroethylene (ETFE) is used as anti-adherent coatings for food packages and radiation dosimeters. In this work, we compare the damage induced in ETFE bombarded with 100 keV Si ions with that induced by 1 MeV proton bombardment. The damage depends on the type, energy and intensity of the irradiation. Irradiated films were analyzed with optical absorption photospectrometry, Raman spectroscopy and Fourier transform infrared (FTIR) spectroscopy to determine the chemical nature of the structural changes caused by ion irradiation. Computer simulations were performed to evaluate the radiation damage.

Minamisawa, R. A.; De Almeida, A.; Abidzina, V.; Parada, M. A.; Muntele, I.; Ila, D.

2007-04-01

56

Medium energy ion scattering analysis of low energy chlorine ion bombarded gallium-arsenide  

NASA Astrophysics Data System (ADS)

This study looks at 35Cl + bombardment of GaAs(001) in the energy range 300 eV to 5 keV for doses between 10 12 and 2 × 10 16 ions cm -2. Experimental studies using medium energy ion scattering (MEIS) in double alignment were complemented by computer simulation (IMPETUS code) of the 35Cl build up and atomic mixing processes. Clear evidence for dramatic changes in the damage buildup in the energy range 500 eV to 1 keV has been found. The contribution of the accumulated 35Cl to the number of displaced Ga and As atoms, and the effects of the analysing 105 keV H +2 beam are also discussed. It was found that 35Cl trapped in the near surface region of the GaAs, after 1 keV 35Cl + ion bombardment, was removed from the sample as a result of bombardment by the analysing H +2 beam.

Orrman-Rossiter, Kevin G.; Baht, Rashpal S.; Badheka, Ranjan; Wadsworth, Mike; Armour, D. G.

1989-04-01

57

Stellar neutron capture on 180 Tam . I. Cross section measurement between 10 keV and 100 keV  

NASA Astrophysics Data System (ADS)

The neutron capture cross section of 180 Tam has been measured at energies between 10 keV and 100 keV in a time-of-flight experiment at the Karlsruhe 3.7 MV Van de Graaff accelerator. Neutrons were produced via the 7Li ( p,n ) 7Be reaction by bombarding metallic Li targets with a pulsed proton beam, and gold was used as a cross section standard. Though the world supply of enriched 180 Tam was available for this experiment, the sample consisted of only 150 mg Ta2 O5 with a 180 Tam content of only 5.5% . The difficult separation of the comparably few capture events in 180 Tam from the much larger background due to captures in 181 Ta could be achieved by means of the Karlsruhe 4? barium fluoride detector, taking advantage of its combination of high efficiency, good energy resolution, and high granularity. The cross section was determined with an overall uncertainty of better than 10% in the energy range from 30 keV to 100 keV and could be used for renormalizing statistical model calculations in the entire energy range of astrophysical interest, which had predicted about two times larger values. Based on these first experimental data, Maxwellian averaged neutron capture cross sections were calculated for thermal energies between kT=8 keV and 100 keV .

Wisshak, K.; Voss, F.; Arlandini, C.; Käppeler, F.; Heil, M.; Reifarth, R.; Krti?ka, M.; Be?vá?, F.

2004-05-01

58

Thermionic emission from giant fullerenes  

Microsoft Academic Search

Large even-numbered carbon clusters in the size range from 100 to 600 atoms (giant fullerenes) were generated by laser vaporization and directly injected as positive ions via a supersonic beam into the magnetic trap of an ion cyclotron resonance apparatus. Intense laser excitation of the magnetically levitated fullerenes at 4.0 eV was found to result in production of multiply charged

S. Maruyama; M. Y. Lee; R. E. Haufler; Y. Chai; R. E. Smalley

1991-01-01

59

42nd Bombardment Squadron (Heavy). History of the 42nd Bombardment Squadron (Heavy) 1940 - 1944  

E-print Network

History of the 42d Bombardment Squadron (H). 1940 ? 1944. 42nd Bombardment Squadron (H), 11th Bombardment Group (H), 7th Air Force (1941-January 1943); 13th Air Force (January 1943 - ) Air Force Historical Association..., IRIS No. 44028. Mission Reports, 18 July 1942 ? 10 August 1943. This copy of the History of the 42nd Bombardment Squadron was digitized from the microfilm copy (Air Force Historical Association, IRIS No. 44028) obtained from the Air Force...

United States Army Air Corps; United States Army Air Corps

1946-01-01

60

Nanometer-scale sharpening and surface roughening of ZnO nanorods by argon ion bombardment  

NASA Astrophysics Data System (ADS)

We report the effects of exposing a hydrothermally grown, single crystalline ZnO nanorod array to a beam of 50 keV argon ions at room temperature. High resolution electron microscopy reveals that the ion bombardment results in a nanometer-scale roughening of the nanorod sidewalls, which were almost atomically flat in the pristine sample. Ion bombardment further causes the flat, ?100 nm diameter nanorod tips to get sharpened to ultrafine points less than 10 nm across. While tip sharpening is attributed to preferential sputtering, the formation of crystalline surface protuberances can be ascribed to surface instability due to curvature dependent sputtering and surface diffusion under argon-ion bombardment. Both the nanoscale roughening as well as the tip sharpening are expected to favorably impact a wide variety of applications, such as those involving catalysis, gas sensing, solar cells, field emission and gas discharge.

Chatterjee, Shyamal; Behera, Akshaya K.; Banerjee, Amarabha; Tribedi, Lokesh C.; Som, Tapobrata; Ayyub, Pushan

2012-07-01

61

Diamond film growth from fullerene precursors  

DOEpatents

A method and system are disclosed for manufacturing diamond film. The method involves forming a fullerene vapor, providing a noble gas stream and combining the gas with the fullerene vapor, passing the combined fullerene vapor and noble gas carrier stream into a chamber, forming a plasma in the chamber causing fragmentation of the fullerene and deposition of a diamond film on a substrate. 10 figs.

Gruen, D.M.; Liu, S.; Krauss, A.R.; Pan, X.

1997-04-15

62

Production Of Fullerenic Soot In Flames  

DOEpatents

A method for the production of fullerenic nanostructures is described in which unsaturated hydrocarbon fuel and oxygen are combusted in a burner chamber at a sub-atmospheric pressure, thereby establishing a flame. The condensibles of the flame are collected at a post-flame location. The condensibles contain fullerenic nanostructures, such as single and nested nanotubes, single and nested nanoparticles and giant fullerenes. The method of producing fullerenic soot from flames is also described.

Howard, Jack B. (Winchester, MA); Vander Sande, John B. (Newbury, MA); Chowdhury, K. Das (Cambridge, MA)

2000-12-19

63

Production of fullerenic nanostructures in flames  

DOEpatents

A method for the production of fullerenic nanostructures is described in which unsaturated hydrocarbon fuel and oxygen are combusted in a burner chamber at a sub-atmospheric pressure, thereby establishing a flame. The condensibles of the flame are collected at a post-flame location. The condensibles contain fullerenic nanostructures, such as single and nested nanotubes, single and nested nanoparticles and giant fullerenes. The method of producing fullerenic soot from flames is also described.

Howard, Jack B. (Winchester, MA); Vander Sande, John B. (Newbury, MA); Chowdhury, K. Das (Cambridge, MA)

1999-01-01

64

Sputtering of Water Ice Induced by C60 Bombardment: Onset of Plume Formation I. A. Wojciechowski and B. J. Garrison*  

E-print Network

, leading to the formation of a flow that manifests itself in the angular and velocity distributions caused by C60 projectiles are clearly different from those initiated by isoenergetic Ga atoms. Bombardment of the Ag surface by 15 keV Ga atoms results in a classic collision cascade with 21 Ag atoms

65

Theoretical simulations of atomic and polyatomic bombardment of an organic overlayer on a metallic substrate  

NASA Astrophysics Data System (ADS)

Our previous molecular dynamics simulations on initial test systems have laid the foundation for understanding some of the effects of polyatomic bombardment. In this paper, we describe simulations of the bombardment of a more realistic model system, an overlayer of sec-butyl-terminated polystyrene tetramers on a Ag{1 1 1} substrate. We have used this model system to study the bombardment with Xe and SF 5 projectiles at kinetic energies ranging from 0.50 to 5.0 keV. SF 5 sputters more molecules than Xe, but a higher percentage of these are damaged rather than ejected intact when the bombarding energy is greater than 0.50 keV. Therefore, at energies comparable to experimental values, the efficiency, measured as the yield-to-damage ratio, is greater with Xe than SF 5. Stable and intact molecules are generally produced by upward moving substrate atoms, while fragments are produced by the upward and lateral motion of reflected projectile atoms and fragments from the target molecule. SF 5 is ineffective on this model system because of the densely packed lattice and the high mass of the substrate atoms. Experiments have determined that enhancements in yield with polyatomic projectiles are smaller on thin organic films compared to those found on thick organic targets.

Krantzman, K. D.; Fenno, R.; Delcorte, A.; Garrison, B. J.

2003-04-01

66

Long cycles in fullerene graphs , Frantisek Kardosb  

E-print Network

Long cycles in fullerene graphs Rok Ermana , Frantisek Kardosb and Jozef Miskufb a Department.kardos,jozef.miskuf}@upjs.sk Abstract It is conjectured that every fullerene graph is hamiltonian. Jendrol' and Owens proved [J. Math. Chem. 18 (1995), pp. 83­90] that every fullerene graph on n vertices has a cycle of length at least 4n

Boyer, Edmond

67

Uraninite and Fullerene in Atmospheric Particulates  

E-print Network

Research Uraninite and Fullerene in Atmospheric Particulates S A T O S H I U T S U N O M I Y A , K in carbonaceous matter (e50 nm) similar to fullerene. We have also identified, for the first time, closely. In this study, we have completed mass spectrometry analysis to detect the presence of fullerene and also

Utsunomiya, Satoshi

68

Search for fullerenes in stone meteorites  

Microsoft Academic Search

The possibility of identifying fullerenes in stony meteorites became apparent from a paper given by Radicati de Brozolo. In this paper it was reported that fullerenes were present in the debris resulting from a collision between a micrometeoroid and an orbiting satellite. This fact generated sufficient curiosity to initiate a search for the presence of fullerenes in various stone meteorites.

M. Y. Oester; D. Kuechl; P. P. Sipiera; C. J. Welch

1994-01-01

69

Production of Vacancies by Laser Bombardment  

Microsoft Academic Search

Vacancy concentrations estimated to be as large as 1 at. % have been induced in pure nickel and vanadium foils by bombardment with high-intensity laser pulses. Annealing bombarded foils at temperatures greater than 0. 3Tm (absolute melting point) allows vacancies to form into aggregates. Examples are shown of voids in nickel and faulted loops in vanadium. Possible mechanisms of vacancy

S. A. Metz; F. Schmidlin

1971-01-01

70

Ion Bombardment Experiments Suggesting an Origin for Organic Particles in Pre-Cometary and Cometary Ices  

NASA Technical Reports Server (NTRS)

Simple molecules frozen as mantles of interstellar and circumstellar grains and incorporated into comets are subjected to ion bombardment in the form of cosmic rays, stellar flares, stellar winds, and ions accelerated in stellar wind shocks. The total expected dosage for the variety of situations range from 10 eV/molecule for interplanetary dust subjected to solar flares to 10(exp 6) eV/molecule for material in the T Tauri environment. Utilizing a Van de Graaff accelerator and a target chamber having cryogenic and mass spectrometer capabilities, we have bombarded frozen gases in the temperature range of 10 K to 30 K with 175 keV protons. After irradiation, removal of the ice by sublimation at an elevated temperature in vacuum reveals a fluffy residue. These experiments suggest that processes resulting in the formation of organic particles found in the coma of Comet Halley, "CHON", may have included ion bombardment. Also, the moderate energy (100 keV to 500 keV) shock accelerated ion environment of bipolar outflow of stars in the planetary nebula stage such as the Red Rectangle, could produce complex molecular species which emit the observed unidentified infrared bands at 3.3 micro-m, 6.2 micro-m, 7.7 micro-m, 8.6 micro-m, and 11.3 micro-m.

Wdowiak, Thomas J.; Robinson, Edward L.; Flickinger, Gregory C.; Boyd, David A.

1997-01-01

71

Study of the Ar LMM spectra by He + projectile at 1250 keV, 1500 keV and 2000 keV bombardment energies  

NASA Astrophysics Data System (ADS)

The influence of He + ion impact on the Ar LMM spectra was investigated at the ESA-21 electron spectrometer using three different ion energies. Observed line relative energies to the L 3M 2,3( 1D 2) line agree well with other results, but the relative intensities of five angular-isotropic lines deviate significantly from other measurements and theory. The angular dependence of energy shifts agrees with the quantum PCI theory of Barrachina and Macek, except for directions close to 180°, where a slight enhancement of energy shift was observed. Finally, the angular distributions of the L 2M 2,3( 1S 0), ( 1d 2) and ( 3P 0,1,2) line intensities were compared to the alignment theory of Sizov and Kabachnik.

Tóth, L.; Víkor, Gy.; Ricz, S.; Pelicon, P.; Miller, R.

1994-03-01

72

Energetic ion bombardment of Ag surfaces by C60+ and Ga+ projectiles.  

PubMed

The ion bombardment-induced release of particles from a metal surface is investigated using energetic fullerene cluster ions as projectiles. The total sputter yield as well as partial yields of neutral and charged monomers and clusters leaving the surface are measured and compared with corresponding data obtained with atomic projectile ions of similar impact kinetic energy. It is found that all yields are enhanced by about one order of magnitude under bombardment with the C60+ cluster projectiles compared with Ga+ ions. In contrast, the electronic excitation processes determining the secondary ion formation probability are unaffected. The kinetic energy spectra of sputtered particles exhibit characteristic differences which reflect the largely different nature of the sputtering process for both types of projectiles. In particular, it is found that under C60+ impact (1) the energy spectrum of sputtered atoms peaks at significantly lower kinetic energies than for Ga+ bombardment and (2) the velocity spectra of monomers and dimers are virtually identical, a finding which is in pronounced contrast to all published data obtained for atomic projectiles. The experimental findings are in reasonable agreement with recent molecular dynamics simulations. PMID:16099165

Sun, Shixin; Szakal, Christopher; Winograd, Nicholas; Wucher, Andreas

2005-10-01

73

Fullerenes and PAHs in space.  

NASA Astrophysics Data System (ADS)

Theoretical, observational and laboratory work on the new form of carbon known as fullerenes and its hydrogenated forms (fulleranes) are reviewed. These molecules can be responsible of diffuse interstellar bands, the UV bump, a major feature in the extinction curves measured in many lines of sight in our Galaxy and other galaxies and the anomalous microwave emission detected in several regions of star formation,in molecular clouds and HII regions. Recent detections of fullerenes C60 and C70 in planetary nebulae of our Galaxy and in the Magallanic cloud render support to the hypothesis that fullerenes and fulleranes are carriers of these processes. Other potential agents of these emission and absorption processes are the polycyclic aromatic hydrocarbons (PAHs). We also review observational efforts to identify the most simple PAHs, naphthalene and anthracene, in regions of anomalous microwave emission.

Iglesias-Groth, S.

74

Photofragmentation of Fullerene Molecular Ions  

NASA Astrophysics Data System (ADS)

Experimental results are reported for single ionization and ionization with fragmentation of the fullerene molecular ions C60^+ and C70^+ after excitation by monochromatized vacuum ultraviolet synchrotron radiation at different photon energies: 22 eV, 35 eV, 65 eV, 105 eV and 140 eV. Since fullerenes are composed of even numbers of carbon atoms, the fragmentation occurs by the loss of differing numbers of carbon atom pairs. The energy dependences of relative cross sections for direct photoionization yielding C60^2+ and C70^2+ are compared with those for forming different doubly charged fullerene fragment ions. This research was supported by the Division of Chemical Sciences, Geosciences and Biosciences of the U.S. Department of Energy.

Baral, Kiran; Aryal, Nagendra; Esteves, David; Thomas, Christopher; Phaneuf, Ronald; Kilcoyne, David

2012-06-01

75

Periodicity of impurity segregation effects in oxygen bombarded silicon  

NASA Astrophysics Data System (ADS)

Impurity segregation in oxygen bombarded silicon has been studied for eight elements representing four groups of the periodic table. Thin evaporated films of the respective element on silicon were analysed by sputter depth profiling in combination with secondary ion mass spectrometry (SIMS). Upon completion of oxide formation, produced by near-normal oxygen bombardment (10 keV O 2+), the SIMS signals of Cu, Ag, Ga and In showed a rapid fall-off (up to a factor of 4000 for Ag). Thereafter the Cu and Ag signals remained almost constant whereas the Ga and In signals passed through a broad maximum and then decreased exponentially. The observed rapid falloff is considered to be due to strong segregation of the impurity away from the surface to the oxide-silicon interface. From the magnitude of the falloff as well as from the shape of the profiles at larger depths we conclude that the segregation behaviour of different elements can be classified according to the group to which they belong in the periodic table. Impurity transport to the SiO 2/Si interface is not evident in the case of Ge, Sn, Pb and Sb. The present results do not support the previously suggested idea that the magnitude of impurity segregation effects correlates with the Pauling electronegativity of the impurity.

Wittmaack, K.

76

The structure of fullerene compounds  

Microsoft Academic Search

This account reviews fullerene chemistry research at Sussex. C60Ph2 and C60Ph4 have been isolated as minor products from the reaction of C60Cl6 with C6H6 and FeCl3. [70]Fullerene reacts with ICl in C6H6 producing a single isomer of C70Cl10 in high yield. C70Ph8, which has a [5,6] cage double bond that can be selectively functionalized, or C70Ph10 are produced by the

A. G. Avent; A. M. Benito; P. R. Birkett; A. D. Darwish; P. B. Hitchcock; H. W. Kroto; I. W. Locke; M. F. Meidine; B. F. O'Donovan; K. Prassides; R. Taylor; D. R. M. Walton; M. van Wijnkoop

1997-01-01

77

Gold-thiolate cluster emission from SAMs under keV ion bombardment: Experiments and molecular  

E-print Network

on gold is investigated using time-of-flight secondary ion mass spectrometry (ToF-SIMS). Layers out concerning the origin of the gold-thiolate cluster ions observed in the SIMS mass spectra-ordered molecular monolayers on gold. First, we compare and interpret the yields and energy spectra of gold

78

Inorganic Fullerenes, Onions, and Tubes  

NASA Astrophysics Data System (ADS)

Since the exciting and unexpected discovery of the soccerball-shaped Buckminsterfullerene (C 60 ) molecule almost two decades ago, great advances in fullerene research have been made. This includes the discovery of inorganic, noncarbon cage and nanotube structures. Of particular interest are the molybdenum and tungsten sulfides and selenides that, when viewed under an electron microscope, are remarkably similar in appearance to the more famous carbon cages and nanotubes. Among other materials capable of forming fullerene structures, nickel chloride is of importance owing to its potential nanoscale magnetic properties, while the synthesis of pure boron nitride fullerenes, with their fascinating structures, was a particular challenge. All of these materials are able to form closed cages as a result of their sheetlike structure, which can, under the right conditions, curl around and either join with an opposite edge to form a tube or roll up into a scroll. Capping of the structures is possible owing to bends in the sheets caused by the inclusion of defects: pentagons for carbon, squares and octagons for boron nitride, and triangular defects for the sulfides. Proposed applications for the inorganic fullerenes include electronic devices and storage media, probes and electron microscope tips, and nano-ball bearings and high temperature lubricants.

York, Andrew P. E.

2004-05-01

79

Production of high voltage by ion bombardment  

E-print Network

Major Subject: Nuclear Engineering PRODUCTION OF HIGH VOLTAGE BY ION BOMBARDMENT A Thesis by LUCAS CARTER PHINNEY Submitted to Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Approved... as to style and content by: Ron R. Hart (Chair of Committee) Leslie Braby (Member) Don Parker (Member) William Burchill (Head of Department) December 2003 Major Subject: Nuclear Engineering ABSTRACT Production of High Voltage by Ion Bombardment...

Phinney, Lucas Carter

2012-06-07

80

Study of Optical Gain for Fullerene C60 and Fullerene C70  

NASA Astrophysics Data System (ADS)

We have studied the optical gain of Fullerene C60 and Fullerene C70 in toluene solution by variable strip method. The technique involves the comparison of fluorescence emission at different length of pumped material. The gain is found to be positive for a very narrow range of concentration. The optical gain is maximum at 40 ?M concentration for both fullerene molecules. Optical gain is highly concentration dependent and milli molar concentration is not the optimum concentration for the measurement of optical gain. But the value of peak gain for fullerene C70 is more than that of fullerene C60. It may be due to the extent of twisted intermolecular charge transfer (TICT) formation in the excited state is larger for fullerene C70. Therefore, optical gain for fullerene C60 is less than fullerene C70. This is thus an important distinguishing parameter of two sister molecules.

Qaiser, Darakhshan; Khan, Mohd. Shahid; Singh, R. D.; Khan, Zahid H.

2011-10-01

81

Development of Mass Spectrometric Ionization Methods for Fullerenes and Fullerene Derivatives  

EPA Science Inventory

Currently investigations into the environmental behavior of fullerenes and fullerene derivatives is hampered by the lack of well characterized standards and by the lack of readily available quantitative analytical methods. Reported herein are investigations into the utility of ma...

82

Particle bombardment effects on thin-film deposition: A review  

Microsoft Academic Search

In many atomistic film deposition processes, concurrent energetic particle bombardment (ions, atoms, molecules, atom clusters) may occur inadvertently and uncontrollably or bombardment may be used to deliberately modify film properties. These energetic particles can arise from (i) the acceleration of charged particles, (ii) high-energy neutrals from reflection from bombarded surfaces, or (iii) charge exchange processes. Particle bombardment effects that can

D. M. Mattox

1989-01-01

83

Plasma ion source for in situ ion bombardment in a soft x-ray magnetic scattering diffractometer  

SciTech Connect

A new plasma ion source for in situ keV He ion bombardment of solid state samples or thin films was designed and built for ion fluences between 1 x 10{sup 12} and 1 x 10{sup 17} ions/cm{sup 2}. The system was designed to be mounted to different diffraction chambers for soft x-ray resonant magnetic scattering. Without breaking the vacuum due to He-ion bombardment, structural and magnetic modifications of the samples can be studied in situ and element specifically.

Lengemann, Daniel; Engel, Dieter; Ehresmann, Arno [Institute of Physics, EP IV, University of Kassel, Heinrich-Plett-Str.40, 34132 Kassel (Germany) and Center for Interdisciplinary Nanostructure Science and Technology (CINSaT), University of Kassel, Heinrich-Plett-Str.40, 34132 Kassel (Germany)

2012-05-15

84

Superabsorbing Fullerenes: Spectral and Kinetic Characterization of Photoinduced Interactions in Perylenediimide-Fullerene-C60 Dyads  

E-print Network

Superabsorbing Fullerenes: Spectral and Kinetic Characterization of Photoinduced Interactions in Perylenediimide-Fullerene-C60 Dyads Je´ro^me Baffreau, Ste´phanie Leroy-Lhez, Pie´trick Hudhomme, Michiel M energy transfer to the fullerene unit, as shown with femtosecond transient absorption spectroscopy

van Stokkum, Ivo

85

Study of Optical Gain for Fullerene C60 and Fullerene C70  

Microsoft Academic Search

We have studied the optical gain of Fullerene C60 and Fullerene C70 in toluene solution by variable strip method. The technique involves the comparison of fluorescence emission at different length of pumped material. The gain is found to be positive for a very narrow range of concentration. The optical gain is maximum at 40 muM concentration for both fullerene molecules.

Darakhshan Qaiser; Mohd. Shahid Khan; R. D. Singh; Zahid H. Khan

2011-01-01

86

Study of Optical Gain for Fullerene C60 and Fullerene C70  

Microsoft Academic Search

We have studied the optical gain of Fullerene C60 and Fullerene C70 in toluene solution by variable strip method. The technique involves the comparison of fluorescence emission at different length of pumped material. The gain is found to be positive for a very narrow range of concentration. The optical gain is maximum at 40 ?M concentration for both fullerene molecules.

Darakhshan Qaiser; Mohd. Shahid Khan; R. D. Singh; Zahid H. Khan

2011-01-01

87

Synthesis, properties and transformations of fullerene peroxides  

NASA Astrophysics Data System (ADS)

Methods of synthesis, properties and transformations of fullerene peroxides are considered and systematized for the first time. It is shown that the chemistry of fullerene peroxides is a new approach to functionalization of fullerenes, which has been intensively developing since 2002. Methods of synthesis, mechanisms of formation and reactions of C60 and C70 alkyl peroxides with or without epoxide moieties are discussed. Transformations of fullerene peroxides affording a wide range of fullerene derivatives containing, as addends, halogen or sulfur atoms; epoxide, dioxolane, thiirane, crown ether, aziridine and dioxetane rings, as well as hydroxyl, alkoxyl and carbonyl groups, are considered. Special attention is focused on reactions constituting the basis of a new approach — so-called molecular surgery, which enables the synthesis of open-cage fullerene derivatives. It has been demonstrated that such compounds are good candidates for designing photovoltaic cells and carriers of drugs and radionuclides (for radiopharmaceuticals). The bibliography includes 130 references.

Bulgakov, R. G.; Galimov, D. I.; Dzhemilev, U. M.

2014-08-01

88

Sputtering Yields for C60 and Au3 Bombardment of Water Ice as a Function of Incident Kinetic Energy  

PubMed Central

The total sputtering yields for water ice due to kiloelectronvolt cluster bombardment have been measured and compared to the predictions made by the mesoscale energy deposition footprint (MEDF) model. For C60 bombardment the experimental yield varies almost linearly from 820 water molecule equivalents at an incident kinetic energy of 10 keV to 10100 water molecule equivalents at a kinetic energy of 120 keV. For Au3 bombardment the experimental yield varies almost linearly from 630 water molecule equivalents at an incident energy of 10 keV and rises to 1200 water molecule equivalents at 25 keV. The MEDF model is used to calculate relative yield trends with respect to incident energy using short time molecular dynamics simulations. The results of these calculations indicate that the model can effectively predict the yield trends observed for these two clusters in experiments, although there is a consistent overestimate of the predicted induced C60 yield. It is hypothesized that this overestimate can be explained by the absence of reactions and ionization processes in the current simulations. Despite this omission experimental yield trends can be accurately predicted using relatively small amounts of computer time. The success of the model in predicting the yield of water from ice films using a variety of energies and projectiles suggests this approach may greatly aid in the optimization of experimental configurations. PMID:17503768

Russo, Michael F.; Szakal, Christopher; Kozole, Joseph; Winograd, Nicholas; Garrison, Barbara J.

2008-01-01

89

Statistical mechanics of fullerene coalescence growth  

SciTech Connect

Among the different carbon allotropes fullerenes are exceptionally intriguing for their spheroidal topology out of pentagons and hexagons. However, the dominant formation mode is still ambiguous. Here, we analyze the fullerene formation process by the statistical analysis of fullerene sizes produced in a laser-induced microplasma finding that a simple two-parameter lognormal distribution describes impressively well the cluster frequencies under various conditions. Our findings clearly reveal coalescent growth following a classical collision dynamics and disagree with several earlier assumptions.

Maul, Jochen; Berg, Thomas; Schoenhense, Gerd; Huber, Gerhard [Institut fuer Physik, Johannes Gutenberg-Universitaet, Staudingerweg 7, D-55099 Mainz (Germany); Marosits, Edit [Max Planck-Institut fuer Chemie, Becherweg 27, D-55128 Mainz (Germany)

2006-10-15

90

Fullerene-silica complexes for medical chemistry  

Microsoft Academic Search

A quantum-chemical study of the interaction of C60 fullerene with nanosized silica was performed. It was demonstrated that a fullerene molecule forms a weakly bound complex\\u000a with a pyrogenic silica (Aerosil) particle only via the interaction with the silanediol groups of the hydroxyl covering on\\u000a the particle. By contrast, a fullerene molecule is not bonded to an individual siloxane cycle,

E. F. Sheka

2007-01-01

91

C(240)-----The most Chemically Inert Fullerene?  

NASA Technical Reports Server (NTRS)

The reactivity of the fullerenes is primarily a function of their strain, as measured by the pyramidalization angle or curvature of the conjugated carbon atoms. The development of faceting in the structure of large icosahedral fullerenes leads to a minimum in the value of the maximum fullerene pyramidalization angle that lies in the vicinity of C-240. On this basis it is argued that C-240 will be the most chemically inert fullerene. This observation explains the production of [10,10] single-walled nanotubes because a C-240 hemisphere is required for the nucleation of such tubes.

Haddon, R. C.; Scuseria, G. E.; Smalley, R. E.

1997-01-01

92

Development of Advanced Alloys using Fullerenes  

NASA Technical Reports Server (NTRS)

Development of advanced alloys using fullerenes is currently underway to produce materials for use in the extravehicular mobility unit (EMU). These materials will be directed toward commercial usages as they are continually developed. Fullerenes (of which the most common is C(sub 60)) are lightweight, nanometer size, hollow molecules of carbon which can be dispersed in conventional alloy systems to enhance strength and reduce weight. In this research, fullerene interaction with aluminum is investigated and a fullerene-reinforced aluminum alloy is being developed for possible use on the EMU. The samples were manufactured using standard commercial approaches including powder metallurgy and casting. Alloys have been processed having 1.3, 4.0 and 8.0 volume fractions of fullerenes. It has been observed that fullerene dispersion is related to the processing approach and that they are stable for the processing conditions used in this research. Emphasis will be given to differential thermal analysis and wavelength dispersive analysis of the processed alloys. These two techniques are particularly useful in determining the condition of the fullerenes during and after processing. Some discussion will be given as to electrical properties of fullerene-reinforced materials. Although the aluminum and other advanced alloys with fullerenes are being developed for NASA and the EMU, the properties of these materials will be of interest for commercial applications where specific Dual-Use will be given.

Sims, J.; Wasz, M.; O'Brien, J.; Callahan, D. L.; Barrera, E. V.

1994-01-01

93

Effect of ion bombardment on the field emission property of tetrapod ZnO  

SciTech Connect

The influences of ion bombardment on the field emission performance of tetrapod ZnO nanostructures are reported. As the scanning electron microscopy images and photoluminescence spectrum show, the tips of the field emitters are destroyed and the surface state of the field emitters is also changed after the ion bombardment. The ion bombardment has a considerable effect on the field emission properties of the tetrapod ZnO field emitters. After Ar{sup +} ion bombardment with the energy of 3 keV and the ion current of 0.05 {mu}A for 30 min, the turn-on field increases about 63% and the threshold field increases about 77%, respectively. There are two main reasons for the variation in field-emission property: (1) the decrement of the field enhancement factor {beta}, which is caused by the variation in morphology of field emitter; (2) the increment of work function {phi}, which is caused by the changed concentration of the surface oxygen vacancy.

Cui Yunkang [School of Electronic Science and Engineering, Southeast University, Nanjing 210096 (China); Department of Basic Courses, Nanjing Institute of technology, Nanjing 210013 (China); Zhang Xiaobing; Lei Wei [School of Electronic Science and Engineering, Southeast University, Nanjing 210096 (China); Jiangsu Information Display Engineering Research Center, Nanjing 210096 (China); Di Yunsong [School of Physics and Technology, Nanjing Normal University, Nanjing 210097 (China); Wang Jinchan; Yang Xiaxi [School of Electronic Science and Engineering, Southeast University, Nanjing 210096 (China)

2010-03-15

94

Mixed resolution model for C 60 cluster bombardment of solid benzene  

NASA Astrophysics Data System (ADS)

Molecular dynamics simulations of C 60 cluster bombardment have been instrumental in elucidating physical phenomena related to the sputtering process; however, chemical phenomena can also play an important role in C 60 cluster bombardment of molecular solids. Therefore, a mixed resolution model of C 60 cluster bombardment is being developed, where the reactive zone is represented by an all atom region, and the remaining part of the target is described by a coarse-grained representation. A reactive many body potential describes the interactions among atoms; whereas, pair potentials describe the interactions between coarse-grained beads and between coarse-grained beads and atoms. Solid benzene is used to develop the methodology of blending the potentials. The blending of potentials is evaluated by the differences in the velocities of the pressure waves (generated by the C 60 impact) between the all atom benzene, coarse-grained benzene and the mixed resolution benzene systems. Initial testing with 1 keV C 60 cluster bombardment simulations show a smooth transition between regions.

Kennedy, Paul E.; Garrison, Barbara J.

2011-07-01

95

Ion bombardment of Zr 3Fe  

NASA Astrophysics Data System (ADS)

Ion bombardments, transmission electron muscopy (TEM) and analytical electron muscopy (AEM) techniques were used to obtain information on the effect of irradiation on the phase stability of Zr 3Fe, which has an orthorhombic crystal structure. 40Ar ion bombardments were performed at 35-773 K. using 1.5, 1.0 and 0.5 MeV ions, successively. The resulting irradiation damage was distributed over a depth of ˜ l ?m. At low ion fluences (10 11-10 12 ions cm -2), the damaged regions appeared as small defects (1.0-5.0 nm diameter) exhibiting strain contrast features. At higher ion fluences (10 13-10 15 ions cm -2), there was an appreciable overlap of the strain-contrast regions, thus resulting in a more complex appearance. In the fluence regime 1 × 10 14-1 × 10 16 ions cm -2, there was a gradual transition from the crystalline to amorphous state at temperatures of 35-473 K. The fluence required to amorphize a given fraction of the irradiated volume was quite dependent upon the amount of annealing that occurred within the collision cascade at the temperature of the bombardment. At temperatures above ˜ 623 K, Zr 3Fe remained crystalline during ion bombardments. Post-irradiation annealing experiments performed at 500-623 K, on Zr 3Fe which had been rendered amorphous during ion bombardment, revealed the nucleation and growth of crystalline Zr 3Fe regions within the amorphous matrix.

Howe, L. M.; McCooeye, D. P.; Rainville, M. H.; Bonnett, J. D.; Phillips, D.

1991-07-01

96

Extraterrestrial Helium (He@C60) Trapped in Fullerenes in the Sudbury Impact Structure  

NASA Technical Reports Server (NTRS)

Fullerenes (C60 and C70) have recently been identified in a shock-produced breccia (Onaping Formation) associated with the 1.85-Ga Sudbury Impact Crater. The presence of parts-per-million levels of fullerenes in this impact structure raises interesting questions about the processes that led to the formation of fullerenes and the potential for delivery of intact organic material to the Earth by a large bolide (e.g., asteroid or comet). Two possible scenarios for the presence of fullerenes in the Sudbury impact deposits are that (1) fullerenes are synthesized within the impact plume from the C contained in the bolide; or (2) fullerenes are already present in the bolide and survived the impact event. The correlation of C and trapped noble gas atoms in meteorites is well established. Primitive meteorites contain several trapped noble gas components that have anomalous isotopic compositions, some of which may have a presolar origin. Several C-bearing phases, including SiC, graphite, and diamond, have been recognized as carriers of trapped noble gases. It has also been suggested that fullerenes (C60 and C70) might be a carrier of noble gas components in carbonaceous chondrites. Recently, fullerenes have been detected in separate samples in the Allende meteorite. Carbon-60 is large enough to enclose the noble gases He, Ne, Ar, Kr, and Xe, but it is too small to contain diatomic gases such as N2 or triatomic gases such as CO2. Recent experimental work has demonstrated that noble gases of a specific isotopic composition can be introduced into synthetic fullerenes at high temperatures and pressures; these encapsulated gases can then be released by the breaking of one or more C bonds during step-heating under vacuum. These thermal-release patterns for He encapsulated within the C60 molecule (He@C60) are similar to the patterns for acid residues of carbonaceous chondrites, suggesting that fullerenes could be an additional carrier of trapped noble gases in acid residues of meteorites. Analysis and Results: In order to characterize the noble gas compositions of the Sudbury fullerenes, we undertook a systematic study of acid-resistant residues throughout the C-rich layer (Black member) of the Onaping Formation. Samples were demineralized and extracted using standard techniques. The Onaping extracts were analyzed using several techniques, including UV-Vis adsorption, electro spray mass spectrometry, and laser desorption (linear and reflectron) time-of-flight (TOF) mass spectrometry (LDMS). The Sudbury fullerenes were then separated and purified using HPLC coupled with a photo diode array detector. The HPLC extracts containing the purified fullerenes were loaded into a metal tube furnace within a glove box under a N atmosphere in preparation for noble gas analyses. The 3-He and 4-He content of the fullerene extracts was measured using previously reported standard techniques . Discussion: Fullerenes (C60 and C70) in the Sudbury Impact Structure have been found to contain trapped He with a 3-He/4-He ratio greater than 5 x 10(exp -4). The 3-He/4-He ratio exceeds the accepted solar value by more than 30% and is more than 10x higher than the maximum reported mantle value. Terrestrial nuclear reactions or cosmic-my bombardment are not sufficient to generate such a high ratio. The 3-He/4-He ratios in the Sudbury fullerenes are similar to those determined for interplanetary dust particles. The greater-than-solar ratios of 3-He/4-He in the Sudbury fullerenes may indicate a presolar origin, although alternative mechanisms occurring in the ISM to explain these high ratios (e.g., spallation reactions, selective He implantation, etc.) cannot be entirely ruled out. We are currently attempting to isolate enough fullerene material to measure anomalous Ne (or Kr or Xe) contained within the C60 (e.g., the "pure" 22-Ne component) and thus determine whether the Sudbury fullerenes are indeed presolar in origin.

Becker, L.; Bada, J. L.; Poreda, R. J.; Bunch, T. E.

1997-01-01

97

A Constructive Enumeration of Fullerenes  

Microsoft Academic Search

In this paper, a fast and complete method to enumerate fullerene structures is given. It is based on a top-down approach, and it is fast enough to generate, for example, all 1812 isomers ofC60in less than 20 s on an SGI-workstation. The method described can easily be generalized for 3-regular spherical maps with no face having more than 6 edges

Gunnar Brinkmann; Andreas W. M. Dress

1997-01-01

98

Photophysics of fullerenes: Thermionic emission  

SciTech Connect

Multiphoton ionization of fullerenes using long-pulse length lasers occurs mainly through vibrational autoionization. In many cases the laser ionization can be described as thermionic in analogy to the boiling off of electrons from a filament. Thermionic emission manifests itself as a delayed emission of electrons following pulsed laser excitation. Klots has employed quasiequilibrium theory to calculate rate constants for thermionic emission from fullerenes which seem to quantitatively account for the observed delayed emission times and the measured electron energy distributions. The theory of Klots also accounts for the thermionic emission of C{sub 60} excited by a low power CW Argon Ion laser. Recently Klots and Compton have reviewed the evidence for thermionic emission from small aggregates where mention was also made of experiments designed to determine the effects of externally applied electric fields on thermionic emission rates. The authors have measured the fullerene ion intensity as a function of the applied electric field and normalized this signal to that produced by single photon ionization of an atom in order to correct for all collection efficiency artifacts. The increase in fullerene ion signal relative to that of Cs{sup +} is attributed to field enhanced thermionic emission. From the slope of the Schottky plot they obtain a temperature of approximately 1,000 K. This temperature is comparable to but smaller than that estimated from measurements of the electron kinetic energies. This result for field enhanced thermionic emission is discussed further by Klots and Compton. Thermionic emission from neutral clusters has long been known for autodetachment from highly excited negative ions. Similarly, electron attachment to C{sub 60} in the energy range from 8 to 12 eV results in C{sub 60} anions with lifetimes in the range of microseconds. Quasiequilibrium theory (QET) calculations are in reasonable accord with these measurements.

Compton, R.N. [Univ. of Tennessee, Knoxville, TN (United States)]|[Oak Ridge National Lab., TN (United States); Tuinman, A.A. [Univ. of Tennessee, Knoxville, TN (United States); Huang, J. [Ames Lab., IA (United States)

1996-09-01

99

Microscopic insights into the sputtering of thin organic films on Ag{111} induced by C60 and Ga bombardment.  

PubMed

Molecular dynamics computer simulations have been employed to model the bombardment of Ag{111} covered with three layers of C6H6 by 15 keV Ga and C60 projectiles. The study is aimed toward examining the mechanism by which molecules are desorbed from surfaces by energetic cluster ion beams and toward elucidating the differences between cluster bombardment and atom bombardment. The results show that the impact of the cluster on the benzene-covered surface leads to molecular desorption during the formation of a mesoscopic scale impact crater via a catapulting mechanism. Because of the high yield of C6H6 with both Ga and C60, the yield enhancement is observed to be consistent with related experimental observations. Specific energy and angle distributions are shown to be associated with the catapult mechanism. PMID:16852476

Postawa, Zbigniew; Czerwinski, Bartlomiej; Winograd, Nicholas; Garrison, Barbara J

2005-06-23

100

Fluorous fullerenes and their properties  

NASA Astrophysics Data System (ADS)

We report the first synthesis of a well-characterized "Teflon ponytail" fullerene adducts via the Hirsch-Bingel reaction with a malonate bearing two perfluorinated alkyl chains. Out of 3 different adducts synthesized, C3 tris-adduct shows excellent solubility in perfluorinated solvents, such as FC-72 and FC-75. It was found to be an efficient sensitizer for singlet oxygen formation in fluorous media, which has potential in biphasic systems and in photobiology. In attempts to develop Fluorous/Organic phase transport systems, several approaches were investigated. Reversible solubilization of Fullerene (C60) in fluorous media by Diels-Alder addition to perfluoroalkylated 1,3-cyclopentadiene was shown to be an unsuitable system, because the Diels-Alder addition of the fluorous diene was accompanied by extensive oxidation of the fullerene core, as revealed by MALDI-TOF data. Perfluoroalkyl substituted alpha and beta-cyclodextrins were synthesized and characterized. Host-guest properties of fluorous cyclodextrins synthesized were investigated in fluorous and mixed fluorous/organic media. The ability of fluorous cyclodextrins to complex small solvent molecules, perfluorocarbon chains and an azo-dye (4,4'-dihydroxyazobenzene) at homogeneous conditions was revealed. However, biphasic extraction of organic substrates by fluorous cyclodextrins from organic into fluorous phase has not been yet achieved.

Yurchenko, Michael E.

101

Fullerenes generated from porous structures.  

PubMed

A class of macromolecules based on the architecture of the well-known fullerenes is theoretically investigated. The building blocks used to geometrically construct these molecules are the two dimensional structures: porous graphene and biphenylene-carbon. Density functional-based tight binding methods as well as reactive molecular dynamics methods are applied to study the electronic and structural properties of these molecules. Our calculations predict that these structures can be stable up to temperatures of 2500 K. The atomization energies of carbon structures are predicted to be in the range of 0.45 eV per atom to 12.11 eV per atom (values relative to the C60 fullerene), while the hexagonal boron nitride analogues have atomization energies between -0.17 eV per atom and 12.01 eV per atom (compared to the B12N12 fullerene). Due to their high porosity, these structures may be good candidates for gas storage and/or molecular encapsulation. PMID:25347301

Paupitz, Ricardo; Junkermeier, Chad E; van Duin, Adri C T; Branicio, Paulo S

2014-12-14

102

Friction and wear measurements of sputtered MoSx films amorphized by ion bombardment  

NASA Astrophysics Data System (ADS)

The present study presents an experimental evidence for amorphization of rf sputtered MoSx films by ion bombardment. Even at low doses (3×1015 ions/cm2) of 400 keV argon ions a complete amorphization was confirmed by x-ray diffraction analysis and transmission electron microscopy. As a result of the ion bombardment the film density increased 100% to almost the bulk value for MoS2. The friction coefficient for ion beam amorphized MoSx was measured to be 0.04 in agreement with the values reported for crystalline films but disagreeing considerably with the friction coefficient of 0.4 previously reported for amorphous films.

Mikkelsen, Niels Jo/rgen; Chevallier, Jacques; So/rensen, Gunnar; Straede, Christen A.

1988-04-01

103

Electronic structure calculations of fullerenes and their derivatives  

Microsoft Academic Search

This book review the fullerene field from the perspective of a theoretician with emphasis on electronic structure. Topics include the theoretical methods currently used; geometry, vibrational frequencies, heats of formation and ionic and excited states of higher fullerenes; small fullerenes, tubular and polymetirc allotropes of carbon, endohedral complexes; fullerene derivatives and solid-state properties of C60 based materials.

J. Cioslowski

1995-01-01

104

Fullerene Graphs and Some Relevant Graph Vesna Andovaa1  

E-print Network

Fullerene Graphs and Some Relevant Graph Invariants Vesna Andovaa1 , Frantisek Kardosb , Riste, Slovenia. E-mail: skrekovski@gmail.com (Received xx.xx, 2013) 1 Introduction Fullerenes are polyhedral is the famous buckminster- fullerene, C60, whose discovery in 1985 marked the birth of fullerene chemistry [40

Paris-Sud XI, Université de

105

Architectures for a Spin Quantum Computer Based on Endohedral Fullerenes  

E-print Network

Architectures for a Spin Quantum Computer Based on Endohedral Fullerenes W. Harneit1 ) (a), C computer using endohedral fullerenes. The fullerene molecule is a static, room-temperature trap for atoms with slowly relaxing electron and nuclear spins. The fullerene "containers" can be used to arrange the spins

Suter, Dieter

106

Cyclic 7-edge-cuts in fullerene graphs Frantisek Kardosa  

E-print Network

Cyclic 7-edge-cuts in fullerene graphs Frantisek Kardosa , Matjaz Krncb , Borut Luzarb and Riste 19, 1111 Ljubljana, Slovenia {matjaz.krnc, borut.luzar}@gmail.com Abstract A fullerene graph-cuts of fullerene graphs of sizes up to 6 is known. In the paper we study cyclic 7-edge connectivity of fullerene

Paris-Sud XI, Université de

107

Electronic structure calculations of fullerenes and their derivatives  

SciTech Connect

This book review the fullerene field from the perspective of a theoretician with emphasis on electronic structure. Topics include the theoretical methods currently used; geometry, vibrational frequencies, heats of formation and ionic and excited states of higher fullerenes; small fullerenes, tubular and polymetirc allotropes of carbon, endohedral complexes; fullerene derivatives and solid-state properties of C60 based materials.

Cioslowski, J.

1995-12-31

108

The stabilization of fused-pentagon fullerene molecules  

Microsoft Academic Search

The isolated pentagon rule (IPR) is now widely accepted as a general rule for determining the stability of all-carbon fullerene cages composed of hexagons and pentagons. Fullerenes that violate this rule have been deemed too reactive to be synthesized. The stabilization of non-IPR endohedral fullerenes depends on charge transfer from the encapsulated metal clusters (endoclusters) to fullerene cages, the electronic

Yuan-Zhi Tan; Su-Yuan Xie; Rong-Bin Huang; Lan-Sun Zheng

2009-01-01

109

Self-assembly of the fullerenes  

Microsoft Academic Search

The account deals with a central mystery of the fullerene story: How are they made How can the fullerenes in general, and C[sub 60] in particular, possibly, be made spontaneously in high yield simply by condensing carbon vapor in a special way The mystery of how this happens in the case of carbon is still by no means fully resolved.

R. E. Smalley

1992-01-01

110

Growth and Sintering of Fullerene Nanotubes  

Microsoft Academic Search

Carbon nanotubes produced in arcs have been found to have the form of multiwalled fullerenes, at least over short lengths. Sintering of the tubes to each other is the predominant source of defects that limit the utility of these otherwise perfect fullerene structures. The use of a water-cooled copper cathode minimized such defects, permitting nanotubes longer than 40 micrometers to

D. T. Colbert; J. Zhang; S. M. McClure; P. Nikolaev; Z. Chen; J. H. Hafner; D. W. Owens; P. G. Kotula; C. B. Carter; J. H. Weaver; A. G. Rinzler; R. E. Smalley

1994-01-01

111

Fullerenes in circumstellar and interstellar environments  

E-print Network

In recent years, the fullerene species C60 (and to a lesser extent also C70) has been reported in the mid-IR spectra of various astronomical objects. Cosmic fullerenes form in the circumstellar material of evolved stars, and survive in the interstellar medium (ISM). It is not entirely clear how they form or what their excitation mechanism is.

Cami, Jan

2012-01-01

112

Direct transformation of graphene to fullerene.  

PubMed

Although fullerenes can be efficiently generated from graphite in high yield, the route to the formation of these symmetrical and aesthetically pleasing carbon cages from a flat graphene sheet remains a mystery. The most widely accepted mechanisms postulate that the graphene structure dissociates to very small clusters of carbon atoms such as C(2), which subsequently coalesce to form fullerene cages through a series of intermediates. In this Article, aberration-corrected transmission electron microscopy directly visualizes, in real time, a process of fullerene formation from a graphene sheet. Quantum chemical modelling explains four critical steps in a top-down mechanism of fullerene formation: (i) loss of carbon atoms at the edge of graphene, leading to (ii) the formation of pentagons, which (iii) triggers the curving of graphene into a bowl-shaped structure and which (iv) subsequently zips up its open edges to form a closed fullerene structure. PMID:20489712

Chuvilin, Andrey; Kaiser, Ute; Bichoutskaia, Elena; Besley, Nicholas A; Khlobystov, Andrei N

2010-06-01

113

Gas storage using fullerene based adsorbents  

NASA Technical Reports Server (NTRS)

This invention is directed to the synthesis of high bulk density high gas absorption capacity adsorbents for gas storage applications. Specifically, this invention is concerned with novel gas absorbents with high gravimetric and volumetric gas adsorption capacities which are made from fullerene-based materials. By pressing fullerene powder into pellet form using a conventional press, then polymerizing it by subjecting the fullerene to high temperature and high inert gas pressure, the resulting fullerene-based materials have high bulk densities and high gas adsorption capacities. By pre-chemical modification or post-polymerization activation processes, the gas adsorption capacities of the fullerene-based adsorbents can be further enhanced. These materials are suitable for low pressure gas storage applications, such as oxygen storage for home oxygen therapy uses or on-board vehicle natural gas storage. They are also suitable for storing gases and vapors such as hydrogen, nitrogen, carbon dioxide, and water vapor.

Loutfy, Raouf O. (Inventor); Lu, Xiao-Chun (Inventor); Li, Weijiong (Inventor); Mikhael, Michael G. (Inventor)

2000-01-01

114

Sorghum genetic transformation by particle bombardment.  

PubMed

Particle bombardment transformation describes the acceleration of high-velocity microparticles coated with exotic genes through the plant-protective cell walls, in order for the introduced genes to be integrated into the host genome. This technique has proven to be an effective and versatile approach towards plant genetic modification in preceding decades. Particle bombardment has been successfully applied to cereals including rice, maize, wheat, barley, and sorghum. Historically, sorghum has been considered as one of the most recalcitrant major crops with regard to successful genetic transformation; however, tremendous progress has been made in recent years. Transformation efficiency by particle bombardment has now improved from approximately 1 % to in excess of 20 % utilizing an optimized tissue culture and DNA delivery system. The protocol described in this chapter routinely generates transformants at 10-25 % efficiency within sorghum genotype Tx430. The process generally takes 11-16 weeks from initiation of immature embryos to planting of transformants. This protocol covers the operation of both the Bio-Rad PDS-1000/He System and particle inflow gun. Three factors are crucial to an efficient particle bombardment transformation system: (1) an efficient tissue culture system, (2) a highly efficient DNA delivery system, and (3) an effective selection strategy. PMID:24243207

Liu, Guoquan; Campbell, Bradley C; Godwin, Ian D

2014-01-01

115

Secondary Emission from Elements Bombarded with Neutrons  

Microsoft Academic Search

In the course of observations of the neutrons produced by the bombardment of elements with accelerated heavy hydrogen ions, we have noticed repeatedly the production of remarkably strong ionising radiations when silver was placed in the beam. Silver is close to tin in the periodic table and it is probable, therefore, that the effects observed by Dr. Ollano are due

M. L. Oliphant

1934-01-01

116

Mesoscale energy deposition footprint model for kiloelectronvolt cluster bombardment of solids.  

PubMed

Molecular dynamics simulations have been performed to model 5-keV C60 and Au3 projectile bombardment of an amorphous water substrate. The goal is to obtain detailed insights into the dynamics of motion in order to develop a straightforward and less computationally demanding model of the process of ejection. The molecular dynamics results provide the basis for the mesoscale energy deposition footprint model. This model provides a method for predicting relative yields based on information from less than 1 ps of simulation time. PMID:17037922

Russo, Michael F; Garrison, Barbara J

2006-10-15

117

Machine Phase Fullerene Nanotechnology: 1996  

NASA Technical Reports Server (NTRS)

NASA has used exotic materials for spacecraft and experimental aircraft to good effect for many decades. In spite of many advances, transportation to space still costs about $10,000 per pound. Drexler has proposed a hypothetical nanotechnology based on diamond and investigated the properties of such molecular systems. These studies and others suggest enormous potential for aerospace systems. Unfortunately, methods to realize diamonoid nanotechnology are at best highly speculative. Recent computational efforts at NASA Ames Research Center and computation and experiment elsewhere suggest that a nanotechnology of machine phase functionalized fullerenes may be synthetically relatively accessible and of great aerospace interest. Machine phase materials are (hypothetical) materials consisting entirely or in large part of microscopic machines. In a sense, most living matter fits this definition. To begin investigation of fullerene nanotechnology, we used molecular dynamics to study the properties of carbon nanotube based gears and gear/shaft configurations. Experiments on C60 and quantum calculations suggest that benzyne may react with carbon nanotubes to form gear teeth. Han has computationally demonstrated that molecular gears fashioned from (14,0) single-walled carbon nanotubes and benzyne teeth should operate well at 50-100 gigahertz. Results suggest that rotation can be converted to rotating or linear motion, and linear motion may be converted into rotation. Preliminary results suggest that these mechanical systems can be cooled by a helium atmosphere. Furthermore, Deepak has successfully simulated using helical electric fields generated by a laser to power fullerene gears once a positive and negative charge have been added to form a dipole. Even with mechanical motion, cooling, and power; creating a viable nanotechnology requires support structures, computer control, a system architecture, a variety of components, and some approach to manufacture. Additional information is contained within the original extended abstract.

Globus, Al; Chancellor, Marisa K. (Technical Monitor)

1997-01-01

118

Attachment of fullerenes to materials: The importance of backbone-fullerene interactions  

NASA Astrophysics Data System (ADS)

Fullerenes undergo Diels-Alder reactions with a number of polymer-supported diene functions. To probe the importance of interactions between the polymer support and the fullerene, we have synthesized hydrophobic (polymer) and hydrophilic (silica) supported furans and cyclopentadienes. Cyclopentadiene reacts efficiently with fullerenes with both hydrophobic and hydrophilic supports. In contrast, supported furans are much more reactive when linked to hydrophobic supports. This indicates the importance of secondary interactions in the creation of these materials.

Nie, Bing; Rotello, Vincent

1997-11-01

119

Material and energy intensity of fullerene production.  

PubMed

Fullerenes are increasingly being used in medical, environmental, and electronic applications due to their unique structural and electronic properties. However, the energy and environmental impacts associated with their commercial-scale production have not yet been fully investigated. In this work, the life cycle embodied energy of C(60) and C(70) fullerenes has been quantified from cradle-to-gate, including the relative contributions from synthesis, separation, purification, and functionalization processes, representing a more comprehensive scope than used in previous fullerene life cycle studies. Comparison of two prevalent production methods (plasma and pyrolysis) has shown that pyrolysis of 1,4-tetrahydronaphthalene emerges as the method with the lowest embodied energy (12.7 GJ/kg of C(60)). In comparison, plasma methods require a large amount of electricity, resulting in a factor of 7-10× higher embodied energy in the fullerene product. In many practical applications, fullerenes are required at a purity >98% by weight, which necessitates multiple purification steps and increases embodied energy by at least a factor of 5, depending on the desired purity. For applications such as organic solar cells, the purified fullerenes need to be chemically modified to [6,6]-phenyl-C(61)-butyric acid methyl ester (PCBM), thus increasing the embodied energy to 64.7 GJ/kg C(60)-PCBM for the specified pyrolysis, purification, and functionalization conditions. Such synthesis and processing effects are even more significant for the embodied energy of larger fullerenes, such as C(70), which are produced in smaller quantities and are more difficult to purify. Overall, the inventory analysis shows that the embodied energy of all fullerenes are an order of magnitude higher than most bulk chemicals, and, therefore, traditional cutoff rules by weight during life cycle assessment of fullerene-based products should be avoided. PMID:21332197

Anctil, Annick; Babbitt, Callie W; Raffaelle, Ryne P; Landi, Brian J

2011-03-15

120

Interatomic Electronic Decay in Endohedral Fullerenes  

SciTech Connect

Ionization of an atom X in an endohedral fullerene complex X at C{sub n} can lead to a wealth of nonradiative decay processes. These interatomic processes occur due to the correlation existing between the atomic and the fullerene electrons and do not take place in the free species X. Considering Ne at C{sub 60} as an example, we calculate the rates of the interatomic decay processes and show that the interatomic decay in Ne at C{sub 60} is ultrafast. Moreover, our analysis suggests that interatomic decay in an endohedral fullerene does not necessarily lead to the destruction of the complex.

Averbukh, Vitali; Cederbaum, Lorenz S. [Theoretische Chemie, Physikalisch-Chemisches Institut, Universitaet Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg (Germany)

2006-02-10

121

Fullerenes for applications in biology and medicine.  

PubMed

Fullerenes as a unique class of carbon allotropes have been studied extensively for their distinctive material properties and potential technological applications, including those in biology and medicine. Since a major focus in the latter has been on drug development and formulation, in this paper we highlight some representative studies related to such a focus, including the use of fullerenes for drug-like functions and for their improving the formulation of established drugs. Also discussed are some other potential medically relevant applications of fullerenes, such as their serving as potent agents in photodynamic therapy and magnetic imaging. PMID:21517770

Anilkumar, P; Lu, F; Cao, L; Luo, P G; Liu, J-H; Sahu, S; Tackett, K N; Wang, Y; Sun, Y-P

2011-01-01

122

Formation and growth of carbon nanostructures: fullerenes, nanoparticles, nanotubes and cones  

Microsoft Academic Search

Various formation models for fullerenes and other carbon nanostructures are reviewed. The formation models considered include fullerene assembling from graphite sheets, 'nautilus' model, assemblage from clusters, 'fullerene road', and carbon cluster annealing. The selection of magic fullerenes and fullerene isomers is discussed. Carbon nanoparticle formation mechanisms are analyzed and their relation to fullerene formation mechanisms is outlined. Molecular dynamics simulation

Yurii E Lozovik; Andrei M Popov

1997-01-01

123

Cathode Ion Bombardment in RF Photoguns  

SciTech Connect

In this paper, we use the method of rapid oscillating field to solve the equation of ion motion in an RF gun. We apply the method to the BNL 1/2-cell SRF photogun and demonstrate that a significant portion of ions produced in the gun can reach the cathode if no special precautions are taken. Also, the paper proposes a simple mitigation recipe that can reduce the rate of ion bombardment.

Pozdeyev,E.; Kayran, D.; Litvinenko, V.

2008-09-01

124

Photoluminescence and optical properties of He ion bombarded ultra-high molecular weight polyethylene  

NASA Astrophysics Data System (ADS)

Ion bombardment is a suitable tool to improve the physical and chemical properties of polymer surface. In this study UHMWPE samples were bombarded with 130 keV He ions to the fluences ranging from 1 × 10 12 to 1 × 10 16 cm -2. The untreated and ion beam modified samples were investigated by photoluminescence, and ultraviolet-visible (UV-vis) spectroscopy. Remarkable decrease in integrated luminescence intensity with increasing ion fluences was observed. The reduction in PL intensity with increase of ion fluence might be attributed to degradation of polymer surface and formation of defects. The effect of ion fluence on the optical properties of the bombarded surfaces was characterized. The values of the optical band gap Eg, and activation energy Ea were determined from the optical absorption. The width of the tail of the localized states in the band gap (E a) was evaluated using the Urbach edge method. With increasing ion fluences a decrease in both the energy gap and the activation energy were observed. Increase in the numbers of carbon atoms ( N) in a formed cluster with increasing the He ion fluence was observed.

Abdul-Kader, A. M.

2009-02-01

125

Applications of Functionalized Fullerenes in Tumor Theranostics  

PubMed Central

Functionalized fullerenes with specific physicochemical properties have been developed for cancer diagnosis and therapy. Notably, metallofullerene is a new class of magnetic resonance imaging (MRI) contrast-enhancing agent, and may have promising applications for clinical diagnosis. Polyhydroxylated and carboxyl fullerenes have been applied to photoacoustic imaging. Moreover, in recent years, functionalized fullerenes have shown potential in tumor therapies, such as photodynamic therapy, photothermal treatment, radiotherapy and chemotherapeutics. Their antitumor effects may be associated with the modulation of oxidative stress, anti-angiogenesis, and immunostimulatory activity. While various types of novel nanoparticle agents have been exploited in tumor theranostics, their distribution, metabolism and toxicity in organisms have also been a source of concern among researchers. The present review summarizes the potential of fullerenes as tumor theranostics agents and their possible underlying mechanisms are discussed. PMID:22509193

Chen, Zhiyun; Ma, Lijing; Liu, Ying; Chen, Chunying

2012-01-01

126

Photoinduced biochemical activity of fullerene carboxylic acid  

SciTech Connect

Here we report the preparation of a water-miscible fullerene carboxylic acid (2) and its biological activity-cytotoxicity and G-selective DNA cleaving ability. What is truly remarkable is that the biological activity of C{sub 60} was observed only under irradiation with visible light and not in the dark, suggesting that fullerenes may serve as useful photosensitive biochemical probes. We have found, for the first time, that even low-energy visible light is surfficient to induce biological activity in fullerene derivatives. Among the numerous implications of the present findings, the most exciting prospect includes the use of fullerene derivatives for photodynamic therapy. 18 refs., 2 figs., 1 tab.

Tokuyama, Hidetoshi; Yamago, Shigeru; Nakamura, Eiichi [Tokyo Inst. of Technology (Japan); Shiraki, Takashi; Sugiura, Yukio [Kyoto Univ. (Japan)

1993-08-25

127

Characterizing Fullerene Nanoparticles in Aqueous Suspensions  

EPA Science Inventory

Studies have indicated that fullerenes can form stable colloidal suspensions in water when introduced to the aqueous phase through solvent exchange, sonication, or extended mixing. The colloidal suspensions created using these techniques have effective aqueous phase concentratio...

128

Fullerene-silica complexes for medical chemistry  

NASA Astrophysics Data System (ADS)

A quantum-chemical study of the interaction of C60 fullerene with nanosized silica was performed. It was demonstrated that a fullerene molecule forms a weakly bound complex with a pyrogenic silica (Aerosil) particle only via the interaction with the silanediol groups of the hydroxyl covering on the particle. By contrast, a fullerene molecule is not bonded to an individual siloxane cycle, and, therefore, fullerosilica gel is formed due to the retention of fullerene molecules in pores of silica gel as a result cooperative action of the siloxane cycles comprising the pore. In both cases, the predicted medico-biological action of medicinal preparations is due to the radical-like and donor-acceptor characteristics of the C60 molecule.

Sheka, E. F.

2007-06-01

129

Inorganic nanotubes and fullerene-like nanoparticles  

Microsoft Academic Search

Although graphite, with its anisotropic two-dimensional lattice, is the stable form of carbon under ambient conditions, on nanometre length scales it forms zero- and one-dimensional structures, namely fullerenes and nanotubes, respectively. This virtue is not limited to carbon and, in recent years, fullerene-like structures and nanotubes have been made from numerous compounds with layered two-dimensional structures. Furthermore, crystalline and polycrystalline

R. Tenne

2006-01-01

130

Self-assembly of tubular fullerenes  

Microsoft Academic Search

Carbon nanotubes in the form of multiwalled fullerenes are shown here to self-assemble under homogeneous gas-phase conditions of carbon condensation in an inert atmosphere heated to 1200$DGR@C-conditions previously thought to be optimal only for the annealing and growth of Cââ and other spheroidal shells. Tubular fullerenes are known to be less stable than their spheroidal counterparts and have thus far

Ting Guo; P. Nikolaev; A. G. Rinzler; Daniel T. Colbert; Richard E. Smalley; D. Tomanek

1995-01-01

131

Photoinduced biochemical activity of fullerene carboxylic acid  

Microsoft Academic Search

Here we report the preparation of a water-miscible fullerene carboxylic acid (2) and its biological activity-cytotoxicity and G-selective DNA cleaving ability. What is truly remarkable is that the biological activity of Cââ was observed only under irradiation with visible light and not in the dark, suggesting that fullerenes may serve as useful photosensitive biochemical probes. We have found, for the

Hidetoshi Tokuyama; Shigeru Yamago; Eiichi Nakamura; Takashi Shiraki; Yukio Sugiura

1993-01-01

132

Fullerene growth from encapsulated graphene flakes  

NASA Astrophysics Data System (ADS)

The direct in situ observation of fullerene formation encapsulated within a graphene ridge has been made possible using an aberration corrected transmission electron microscope (AC-TEM). An atom-by-atom mechanism was proposed based on in situ AC-TEM observations. First principle calculations found a continuous energy decrease upon the addition of carbon atoms to the edge of the graphene flakes, which mimics the fullerene growth steps and supports the atom-by-atom mechanism. The ridged graphene structure worked as a container for pinning small graphene flakes and capturing carbon atoms, which increased the growth probability of the fullerene structure within the small encapsulated space.The direct in situ observation of fullerene formation encapsulated within a graphene ridge has been made possible using an aberration corrected transmission electron microscope (AC-TEM). An atom-by-atom mechanism was proposed based on in situ AC-TEM observations. First principle calculations found a continuous energy decrease upon the addition of carbon atoms to the edge of the graphene flakes, which mimics the fullerene growth steps and supports the atom-by-atom mechanism. The ridged graphene structure worked as a container for pinning small graphene flakes and capturing carbon atoms, which increased the growth probability of the fullerene structure within the small encapsulated space. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr03680h

Neng, Wan; Shuang-Ying, Lei; Jun, Xu; Matteo, Martini; Yi-Long, Zhou; Shu, Wan; Li-Tao, Sun; Qing-An, Huang

2014-09-01

133

Biological Effects of Low Energy Ar+ Ion Bombardment on Silkworm Eggs: a Novel Animal Model  

NASA Astrophysics Data System (ADS)

In this study, we found for the first time that silkworm eggs were able to survive in vacuum for a long period of time. Subsequently, low energy Ar+ ions with different energies and fluences were used to bombard silkworm eggs so as to explore the resulting biological effects. Results showed that (i) the exposure of silkworm eggs to vacuum within 10 min did not cause significant impact on the hatching rates, while the irradiation of silkworm eggs by Ar+ ions of 25 keV or 30 keV with fluences ranging from 2.6×2.6 × 1015 ion/cm2 to 8×2.6 × 1015 ion/cm2 caused a significant impact on the hatching rates, and the hatching rates decreased with the increase in the fluence and energy level; (ii) the irradiation of silkworm eggs by Ar+ ions of 30 keV with a fluence of 8×2.6 × 1015 ion/cm2 or 9×2.6 × 1015 ion/cm2 resulted in a noticeable etching on the egg shell surface which could be observed by a scanning electron microscope; and (iii) the irradiation of silkworm eggs by Ar+ ions of 30 keV with a fluence of 9×2.6 × 1015 ion/cm2 generated several mutant phenotypes which were observed in the 5th instar silkworms and a moth.

Xu, Jiaping; Wu, Yuejin; Liu, Xuelan; Yuan, Hang; Yu, Zengliang

2009-06-01

134

Calculation of the cross section for charge transfer in fullerene-fullerene collisions  

SciTech Connect

An expression for the charge transfer cross section in fullerene-fullerene collisions is derived by using an instanton approximation for the tunnel splitting of energy levels. The expression is valid in the adiabatic approximation and provides an accurate description of available experimental data.

Iroshnikov, G. S. [Moscow Institute of Physics and Technology (Russian Federation)], E-mail: irosh@orc.ru

2006-11-15

135

Program fullerene: a software package for constructing and analyzing structures of regular fullerenes.  

PubMed

Fullerene (Version 4.4) is a general purpose open-source program that can generate any fullerene isomer, perform topological and graph theoretical analysis, as well as calculate a number of physical and chemical properties. The program creates symmetric planar drawings of the fullerene graph and generates accurate molecular 3D geometries by way of force-field optimization, serving as a good starting point for further quantum theoretical treatments. It includes a number of fullerene-to-fullerene transformations, such as Goldberg-Coxeter transforms, Stone-Wales transforms, Endo-Kroto, Yoshida-Fowler, and Brinkmann-Fowler vertex insertions. The program is written in standard Fortran and C++ and can easily be installed in a Linux or UNIX environment. PMID:23559399

Schwerdtfeger, Peter; Wirz, Lukas; Avery, James

2013-06-30

136

Fullerene derivatives as electron donor for organic photovoltaic cells  

NASA Astrophysics Data System (ADS)

We demonstrated the performance of unconventional, all-fullerene-based, planar heterojunction (PHJ) organic photovoltaic (OPV) cells using fullerene derivatives indene-C60 bisadduct (ICBA) and phenyl C61-butyric acid methyl ester as the electron donors with fullerene C70 as the electron acceptor. Two different charge generation processes, including charge generation in the fullerene bulk and exciton dissociation at the donor-acceptor interface, have been found to exist in such all-fullerene-based PHJ cells and the contribution to the total photocurrent from each process is strongly dependent on the thickness of fullerene donor. The optimized 5 nm ICBA/40 nm C70 PHJ cell gives clear external quantum efficiency responses for the long-wavelength photons corresponding to the dissociation of strongly bound Frenkel excitons, which is hardly observed in fullerene-based single layer reference devices. This approach using fullerene as a donor material provides further possibilities for developing high performance OPV cells.

Zhuang, Taojun; Wang, Xiao-Feng; Sano, Takeshi; Hong, Ziruo; Yang, Yang; Kido, Junji

2013-11-01

137

Polymerization of miniature fullerenes in the cavity of nanotubes.  

PubMed

The polymerization of four fullerenes C(28) in the cavity of closed single-walled carbon nanotube C(740) was investigated. It was shown that the formation of the oligomer of four C(28) fullerenes is observed at the pressure of 37.73 GPa, which is created by means of the charged fullerene C(60). Fullerene C(60) moves under the influence of an external electric field. PMID:23104228

Glukhova, O E; Kolesnikova, A S; Slepchenkov, M M

2013-03-01

138

Fast atom bombardment mass spectrometry of peptides.  

PubMed

The contribution of mass spectrometry to the solution of problems in protein biochemistry was limited until the development of methods of ionization that do not require derivatization or prior vaporization of the sample. Fast atom bombardment (FAB), introduced by Barber et al. in 1981 (1), is one of the most important of these methods, and has been widely applied in the peptide and protein field. In the FAB experiment (Fig. 1), the sample is dissolved in a liquid of low vapor pressure, often glycerol or thioglycerol ("the matrix"), and is bombarded by a beam of energetic particles, such as xenon atoms that sputter sample molecules from the surface layers of the matrix into the mass spectrometer vacuum. Proton or other cation attachment produces abundant (positive) ions characteristic of the sample's molecular mass. A proportion of these molecular ions dissociate, producing structurally informative fragments that are generally less intense than the molecular ions, since the ionization process imparts relatively little excess energy. Negatively charged ions are also generated, and spectra may be recorded in either mode by appropriate selection of the polarity of the ion extraction voltages. At low-mass FAB, spectra are generally dominated by signals attributable to ionization of the matrix. The background of "chemical noise" extending to high mass, which gives FAB spectra their characteristic peak-at-every-mass appearance, is probably attributable to direct hits on sample and matrix molecules by the bombarding species. Figure 2 shows a typical FAB spectrum of the cyclic heptapeptide microcystin-LR, obtained from the cyanobacterium Microcystis aeruginosa. PMID:21400142

Wait, R

1993-01-01

139

Computer simulation study of fullerene translocation through lipid membranes  

E-print Network

Computer simulation study of fullerene translocation through lipid membranes JIRASAK WONG-EKKABUT1 aggregates of fullerene molecules can enter cells and alter their functions, and also cross the blood­brain barrier. However, the mechanisms by which fullerenes penetrate and disrupt cell membranes are still poorly

Wong-Ekkabut, Jirasak

140

Antibacterial Activity of Fullerene Water Suspensions: Effects of  

E-print Network

Antibacterial Activity of Fullerene Water Suspensions: Effects of Preparation Method and Particle and Department of Chemistry, Rice University, Houston, Texas 77005 Fullerene research in biological systems has to aggregate, forming stable fullerene water suspensions (FWS) whose properties differ from those of bulk solid

Alvarez, Pedro J.

141

Photoconductivity in Donor-Acceptor Polyferrocenylsilane-Fullerene Composite Films  

E-print Network

Photoconductivity in Donor-Acceptor Polyferrocenylsilane-Fullerene Composite Films Paul W. Cyr) and fullerenes as the active layers were fabricated. Buckminsterfullerene C60 and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) fullerene derivative were investigated as electron acceptors in the devices

142

FORMATION PROCESS OF EMPTY AND METAL-CONTAINING FULLERENE  

E-print Network

FORMATION PROCESS OF EMPTY AND METAL-CONTAINING FULLERENE MOLECULAR DYNAMICS AND FT-ICR STUDIES mechanism of empty and metal-containing fullerene was studied through MD (molecular dynamics) simulations compared with empty fullerene formation simulation. FT-ICR mass spectrometer directly connected

Maruyama, Shigeo

143

Generating Fullerenes at Random Bor Plestenjak and Tomaz Pisanski  

E-print Network

Generating Fullerenes at Random Bor Plestenjak and Tomaz Pisanski IMFM/TCS, University of Ljubljana, POB 1016, Croatia. Received: 1 #12;Abstract In the present paper a method for generating fullerenes;1. INTRODUCTION Fullerenes and other pure carbon cages remain a subject of active re- search. The mechanism

Plestenjak, Bor

144

A NOTE ON FOWLER-MANOLOPOULOS PREDICTOR OF FULLERENE STABILITY  

E-print Network

A NOTE ON FOWLER-MANOLOPOULOS PREDICTOR OF FULLERENE STABILITY Yang Ju Heng Liang Junwei Zhang of the hexagon neighbor signature, is one of the most powerful predictors for fullerene stability. In this note as an understanding of Fowler-Manolopoulos criterion. 1 Introduction A fullerene Cn is a polyhedral carbon cage with n

Bai, Fengshan

145

Optical absorption spectra and geometric e ects in higher fullerenes  

E-print Network

Optical absorption spectra and geometric e ects in higher fullerenes (Running head: Optical absorption in higher fullerenes) Kikuo Harigaya and Shuji Abe Physical Science Division, Electrotechnical and higher fullerenes, including isomers of C76, C78, and C84, are theoretically investigated. We use a tight

Harigaya, Kikuo

146

Wiener Dimension: Fundamental Properties and (5,0)-Nanotubical Fullerenes  

E-print Network

Wiener Dimension: Fundamental Properties and (5,0)-Nanotubical Fullerenes Yaser Alizadeha , Vesna of dimension 1 is 2-connected. It is shown that the (5, 0)-nanotubical fullerene graph on 10k (k 3) vertices has Wiener dimension k. As a consequence the Wiener index of these fullerenes is obtained. 1

Klavzar, Sandi

147

The Differential Cytotoxicity of Water-Soluble Fullerenes  

E-print Network

The Differential Cytotoxicity of Water-Soluble Fullerenes Christie M. Sayes, John D. Fortner, Wenh, 2004 ABSTRACT We show that the cytotoxicity of water-soluble fullerene species is a sensitive function of surface derivatization; in two different human cell lines, the lethal dose of fullerene changed over 7

Tao, Yizhi Jane

148

The minimal non-fullerene Voronoi polyhedra Bor Plestenjak  

E-print Network

The minimal non-fullerene Voronoi polyhedra Bor Plestenjak Department of Theoretical Computer their associated Voronoi regions de ne a polyhedron that is for most n a fullerene. In this paper the exceptional minimal non-fullerene polyhedra are dis- cussed. In this paper we study uniform distributions of points

Plestenjak, Bor

149

Wiener Dimension: Fundamental Properties and (5,0)Nanotubical Fullerenes  

E-print Network

Wiener Dimension: Fundamental Properties and (5,0)­Nanotubical Fullerenes Yaser Alizadeh a , Vesna and it is proved that a graph of dimension 1 is 2­connected. It is shown that the (5, 0)­nanotubical fullerene of these fullerenes is obtained. 1 Corresponding author #12; 1 Introduction The distance considered in this paper

Klavzar, Sandi

150

The Differential Cytotoxicity of Water-Soluble Fullerenes  

Microsoft Academic Search

We show that the cytotoxicity of water-soluble fullerene species is a sensitive function of surface derivatization; in two different human cell lines, the lethal dose of fullerene changed over 7 orders of magnitude with relatively minor alterations in fullerene structure. In particular, an aggregated form of C 60, the least derivatized of the four materials, was substantially more toxic than

Christie M. Sayes; John D. Fortner; Wenh Guo; Delina Lyon; Adina M. Boyd; Kevin D. Ausman; Yizhi J. Tao; Balaji Sitharaman; Lon J. Wilson; Joseph B. Hughes; Jennifer L. West; Vicki L. Colvin

2004-01-01

151

Asymptotic Shape of a Fullerene Ball T. A. Witten*  

E-print Network

Asymptotic Shape of a Fullerene Ball T. A. Witten* and Hao Li James Franck Institute, University-enclosing elas- tic sheet such as a large fullerene ball of linear dimension R. Stretching deformation is crucial in determining the optimal shape, in conjunc- tion with bending. The asymptotic shape of a symmetrical fullerene

Lee, Ka Yee C.

152

New Structural Parameters and Permanents of Adjacency Matrices of Fullerenes  

E-print Network

New Structural Parameters and Permanents of Adjacency Matrices of Fullerenes Shan Jiang Heng Liang.R.CHINA. (Received November 25, 2004) Abstract The permanent of the adjacency matrix of a fullerene Cn is related. The stepwise regression model is used to predict the permanents of adjacency matrices of fullerenes

Bai, Fengshan

153

Microscopic mechanism of fullerene fusion Seungwu Han,1  

E-print Network

Microscopic mechanism of fullerene fusion Seungwu Han,1 Mina Yoon,2 Savas Berber,2 Noejung Park,3 calculations with a search of phase space, we investigate the microscopic fusion mechanism of C60 fullerenes. We find that the 2+2 cycloaddition reaction, a necessary precursor for fullerene fusion, may

154

Combined effects of fullerene shape and extreme conditions  

E-print Network

1 Combined effects of fullerene shape and extreme conditions on the structure of carbon peapods #12;3 + B.W. Smith, M. Monthioux, D.E. Luzzi, Nature 396, 324 (1998) Fullerene Single walled nanotube Effect of confinement inside NT ? Role of temperature and pressure ? Fullerene polymerization

Paris-Sud 11, Université de

155

ODD CYCLE TRANSVERSALS AND INDEPENDENT SETS IN FULLERENE GRAPHS  

E-print Network

ODD CYCLE TRANSVERSALS AND INDEPENDENT SETS IN FULLERENE GRAPHS LUERBIO FARIA, SULAMITA KLEIN, AND MATEJ STEHL´IK Abstract. A fullerene graph is a cubic bridgeless plane graph with all faces of size 5 and 6. We show that every fullerene graph on n vertices can be made bipartite by deleting at most 12n/5

Boyer, Edmond

156

A FULLERENE FORMATION MODEL PROPOSED FROM MOLECULAR DYNAMICS SIMULATIONS  

E-print Network

A FULLERENE FORMATION MODEL PROPOSED FROM MOLECULAR DYNAMICS SIMULATIONS Yasutaka Yamaguchi distributed carbon atoms was simulated. A C60 imperfect fullerene obtained in the simulation was kept at 2500 in the clustering simulation. Through successive pentagon-migration transformations, the perfect fullerene structure

Maruyama, Shigeo

157

Graph-Theoretic Independence as a Predictor of Fullerene Stability  

E-print Network

Graph-Theoretic Independence as a Predictor of Fullerene Stability S. Fajtlowicz a, C. E. Larson b of a fullerene, the size of the largest set of vertices such that no two are adjacent (corresponding in identifying stable fullerene isomers. The experimentally characterized isomers with 60, 70 and 76 atoms

Larson, Craig E.

158

Nonlinear Optical Response in Higher Fullerenes Kikuo Harigaya  

E-print Network

of extracted higher fullerenes { C70, C76, C78, and C84 { are theoretically investi- gated. Magnitudes of o nonlinearities of higher fullerenes are a few times larger than those of C60. The magnitudes of nonlinearity tend, third-harmonic generation, higher fullerenes, C70, C76, C78, C84, electron- electron interactions

Harigaya, Kikuo

159

Constructing I[subscript h] Symmetrical Fullerenes from Pentagons  

ERIC Educational Resources Information Center

Twelve pentagons are sufficient and necessary to form a fullerene cage. According to this structural feature of fullerenes, we propose a simple and efficient method for the construction of I[subscript h] symmetrical fullerenes from pentagons. This method does not require complicated mathematical knowledge; yet it provides an excellent paradigm for…

Gan, Li-Hua

2008-01-01

160

Pentafluorophenyl transfer reaction: preparation of pentafluorophenyl [60]fullerene adducts through opening of fullerene epoxide moiety with trispentafluorophenylborane.  

PubMed

Unlike the extensively studied perfluoroalkyl fullerene adducts, perfluorophenyl fullerene adducts are quite difficult to prepare by known methods. Trispentafluorophenylborane was found to react with fullerene epoxide to form the 1,2-perfluorophenylfullerenol. The method can be applied to both the simple epoxide C60(O) and fullerene multiadducts containing an epoxide moiety. Single crystal X-ray structure analysis confirmed the addition of the pentafluorophenyl group. PMID:24865369

Liang, Sisi; Xu, Liang; Jia, Zhenshan; Gan, Liangbing

2014-06-20

161

Production of anti-fullerene C 60 polyclonal antibodies and study of their interaction with a conjugated form of fullerene  

Microsoft Academic Search

The aim of this study was to produce anti-fullerene C60 antibodies for the development of detection systems for fullerene C60 derivatives. To produce anti-fullerene C60 antibodies, conjugates of the fullerene C60 carboxylic derivative with thyroglobulin, soybean trypsin inhibitor, and bovine serum albumin were synthesized by carbodiimide\\u000a activation and characterized. Immunization of rabbits by the conjugates led to the production of

O. D. Hendrickson; N. S. Fedyunina; A. A. Martianov; A. V. Zherdev; B. B. Dzantiev

162

Infrared Study of Fullerene Planetary Nebulae  

NASA Astrophysics Data System (ADS)

We present a study of 16 planetary nebulae (PNe) where fullerenes have been detected in their Spitzer Space Telescope spectra. This large sample of objects offers a unique opportunity to test conditions of fullerene formation and survival under different metallicity environments because we are analyzing five sources in our own Galaxy, four in the Large Magellanic Cloud (LMC), and seven in the Small Magellanic Cloud (SMC). Among the 16 PNe studied, we present the first detection of C60 (and possibly also C70) fullerenes in the PN M 1-60 as well as of the unusual ~6.6, 9.8, and 20 ?m features (attributed to possible planar C24) in the PN K 3-54. Although selection effects in the original samples of PNe observed with Spitzer may play a potentially significant role in the statistics, we find that the detection rate of fullerenes in C-rich PNe increases with decreasing metallicity (~5% in the Galaxy, ~20% in the LMC, and ~44% in the SMC) and we interpret this as a possible consequence of the limited dust processing occurring in Magellanic Cloud (MC) PNe. CLOUDY photoionization modeling matches the observed IR fluxes with central stars that display a rather narrow range in effective temperature (~30,000-45,000 K), suggesting a common evolutionary status of the objects and similar fullerene formation conditions. Furthermore, the data suggest that fullerene PNe likely evolve from low-mass progenitors and are usually of low excitation. We do not find a metallicity dependence on the estimated fullerene abundances. The observed C60 intensity ratios in the Galactic sources confirm our previous finding in the MCs that the fullerene emission is not excited by the UV radiation from the central star. CLOUDY models also show that line- and wind-blanketed model atmospheres can explain many of the observed [Ne III]/[Ne II] ratios using photoionization, suggesting that possibly the UV radiation from the central star, and not shocks, is triggering the decomposition of the circumstellar dust grains. With the data at hand, we suggest that the most likely explanation for the formation of fullerenes and graphene precursors in PNe is that these molecular species are built from the photochemical processing of a carbonaceous compound with a mixture of aromatic and aliphatic structures similar to that of hydrogenated amorphous carbon dust.

García-Hernández, D. A.; Villaver, E.; García-Lario, P.; Acosta-Pulido, J. A.; Manchado, A.; Stanghellini, L.; Shaw, R. A.; Cataldo, F.

2012-12-01

163

PAPER www.rsc.org/pps | Photochemical & Photobiological Sciences Ionisation of fullerenes and fullerene clusters using ultrashort laser pulses  

E-print Network

PAPER www.rsc.org/pps | Photochemical & Photobiological Sciences Ionisation of fullerenes and fullerene clusters using ultrashort laser pulses Eleanor E. B. Campbell,*a Klavs Hansen,a Martin Hed review of the literature concerning the ultra-short pulse ionisation of fullerenes in the gas phase

Hansen, Klavs

164

Energetic ion bombarded Fe/Al multilayers  

SciTech Connect

The utility of ion-assisted deposition is investigated to explore the possibility of counteracting the deficiency of back-reflected current of Ar neutrals in the case of lighter elements such as Al. A range of energetically ion bombarded Fe/Al multilayers sputtered with applied surface bias of 0, -200, or -400 V were deposited onto Si(111) substrates in an argon atmosphere of 4 mTorr using a computer controlled dc magnetron sputtering system. Grazing incidence reflectivity and rocking curve scans by synchrotron x rays of wavelength of 1.38 A were used to investigate the structures of the interfaces produced. Substantial evidence has been gathered to suggest the gradual suppression of interfacial mixing and reduction in interfacial roughness with increases of applied bias. The densification of the Al microstructure was noticeable and may be a consequence of resputtering attributable to the induced ion bombardment. The average interfacial roughnesses were calculated for the 0, -200, and -400 V samples to be 7{+-}0.5, 6{+-}0.5, and 5{+-}0.5 A respectfully demonstrating a 30% improvement in interface quality. Data from rocking curve scans point to improved long-range correlated roughness in energetically deposited samples. The computational code based on the recursive algorithm developed by Parratt [Phys. Rev. 95, 359 (1954)] was successful in the simulation of the specular reflectivity curves.

Al-Busaidy, M.S.; Crapper, M.D. [College Science, Physics Department, Sultan Qaboos University, P.O. Box 36, Al-Khod 123 (Oman); Department of Physics, Loughborough University, Loughborough (United Kingdom)

2006-05-15

165

Liposomal Formulation of Amphiphilic Fullerene Antioxidants  

PubMed Central

Novel amphiphilic fullerene[70] derivatives that are rationally designed to intercalate in lipid bilayers are reported, as well as its vesicular formulation with surprisingly high loading capacity up to 65% by weight. The amphiphilic C70 bisadduct forms uniform and dimensionally stable liposomes with auxiliary natural phospholipids as demonstrated by buoyant density test, particle size distribution and 31P NMR. The antioxidant property of fullerenes is retained in the bipolarly functionalized C70 derivative, Amphiphilic Liposomal Malonylfullerene[70] (ALM) as well as in its liposomal formulations, as shown by both electron paramagnetic resonance (EPR) studies and in vitro reactive oxygen species (ROS) inhibition experiments. The liposomally formulated ALM efficiently quenched hydroxyl radicals and superoxide radicals. In addition, the fullerene liposome inhibited radical-induced lipid peroxidation and maintained the integrity of the lipid bilayer structure. This new class of liposomally formulated, amphipathic fullerene compounds represents a novel drug delivery system for fullerenes and provides a promising pathway to treat oxidative stress-related diseases. PMID:20839887

Zhou, Zhiguo; Lenk, Robert P.; Dellinger, Anthony; Wilson, Stephen R.; Sadler, Robert; Kepley, Christopher L.

2010-01-01

166

Nanostructured metal composites reinforced with fullerenes  

NASA Astrophysics Data System (ADS)

This work presents the results of the characterization of nanostructured Al or Fe matrix composites reinforced with fullerenes. The fullerene used is a mix of 15 wt%C60, 5 wt.%C70, and 80 wt.% soot that is the product of the primary synthesis of C60. The composites were produced by mechanical alloying and sintered by spark plasma sintering (SPS). It was found that in both composites, C60 withstands mechanical alloying, and acts as a control agent, reducing the agglomeration of the particles. In both composite systems the as-mechanically alloyed powders as well as the SPS sintered products are nanostructured. During the SPS process the effect of the metal (Al or Fe) matrix with the fullerene is different for each composite. For instance, Al reacts with all the carbon in the fullerene mix and forms Al4C3; on the contrary, in the Fe-fullerene composite, Fe sponsors the synthesis of C60 during the SPS process. The synthesis of the C60 is presumably assisted by the catalytic nature of Fe and the electric field generated during the SPS sintering process.

Robles-Hernández, Francisco C.; Calderon, H. A.

2010-02-01

167

X-ray diffraction study of stress relaxation in cubic boron nitride films grown with simultaneous medium-energy ion bombardment  

NASA Astrophysics Data System (ADS)

Relaxation of the intrinsic stress of cubic boron nitride (cBN) thin films has been studied by x-ray diffraction (XRD) using synchrotron light. The stress relaxation has been attained by simultaneous medium-energy ion bombardment (2-10 keV) during magnetron sputter deposition, and was confirmed macroscopically by substrate curvature measurements. In order to investigate the stress-release mechanisms, XRD measurements were performed in in-plane and out-of-plane geometry. The analysis shows a pronounced biaxial state of compressive stress in the cBN films grown without medium-energy ion bombardment. This stress is partially released during the medium-energy ion bombardment. It is suggested that the main path for stress relaxation is the elimination of strain within the cBN grains due to annealing of interstitials.

Abendroth, B.; Gago, R.; Eichhorn, F.; Möller, W.

2004-12-01

168

Nanostructural magnetism of polymeric fullerene crystals  

SciTech Connect

The nature of magnetism in all-carbon crystals composed of polymeric layers of covalently bound fullerene (C{sub 60}) molecules is considered. The results of quantum-chemical calculations performed using the unrestricted Hartree-Fock approximation and the semiempirical AM1 method are presented. It is shown that the exchange integrals J of both a free C{sub 60} molecule and a monomer unit of the polymer are too large ensure the required magnetic susceptibility of the fullerene crystal. However, the J value exhibits an approximately n-fold decrease for an oligomer molecule consisting of n C{sub 60} units. Therefore, in the case of large n, the exchange integral can be reduced to a low level sufficient to provide for a significant magnetic susceptibility. A nanosize (scaly) model of the observed magnetism is proposed that is consistent with recent experimental data, which are indicative of a nanostructural character of magnetic fullerene samples.

Sheka, E. F., E-mail: sheka@icp.ac.ru; Zaets, V. A. [Peoples Friendship University (Russian Federation); Ginzburg, I. Ya. [Russian Academy of Sciences, Institute for Problems of Chemical Physics (Russian Federation)

2006-11-15

169

Fullerenes in circumstellar and interstellar environments  

E-print Network

We recently identified several emission bands in the Spitzer-IRS spectrum of the unusual planetary nebula Tc 1 with the infrared active vibrational modes of the neutral fullerene species C60 and C70. Since then, the fullerene bands have been detected in a variety of sources representing circumstellar and interstellar environments. Abundance estimates suggest that C60 represents ~0.1%-1.5% of the available carbon in those sources. The observed relative band intensities in various sources are not fully compatible with single-photon heating and fluorescent cooling, and are better reproduced by a thermal distribution at least in some sources. The observational data suggests that fullerenes form in the circumstellar environments of evolved stars, and survive in the interstellar medium. Precisely how they form is still a matter of debate.

Cami, Jan; Peeters, Els; Malek, Sarah E

2011-01-01

170

Fullerenes in Circumstellar and Interstellar Environments  

NASA Astrophysics Data System (ADS)

We recently identified several emission bands in the Spitzer-IRS spectrum of the unusual planetary nebula Tc 1 with the infrared active vibrational modes of the neutral fullerene species C60 and C70. Since then, the fullerene bands have been detected in a variety of sources representing circumstellar and interstellar environments. Abundance estimates suggest that C60 represents ~0.1%-1.5% of the available carbon in those sources. The observed relative band intensities in various sources are not fully compatible with single-photon heating and fluorescent cooling, and are better reproduced by a thermal distribution at least in some sources. The observational data suggests that fullerenes form in the circumstellar environments of evolved stars, and survive in the interstellar medium. Precisely how they form is still a matter of debate.

Cami, Jan; Bernard-Salas, Jeronimo; Peeters, Els; Malek, Sarah E.

2011-12-01

171

Electric dipole emission by fullerenes and buckyonions  

E-print Network

We study the rotation rates and electric dipole emission of hydrogenated icosahedral fullerenes (single and multishell) in various phases of the interstellar medium. Using the formalism of Draine and Lazarian for the rotational dynamics of these molecules in various astrophysical environments, we find effective rotation rates in the range 1-65 GHz with a trend toward lower rotational frequency as the radius of the molecule increases. Owing to the moderately polar nature of the C--H bond, hydrogenated fullerenes (fulleranes) are expected to have a net dipole moment and produce electric dipole radiation. Adopting the same size distribution proposed for fullerenes in the study of the UV extinction bump (2175 \\AA) we predict the dipole electric emission of mixtures of fulleranes for various levels of hydrogenation. We find that these molecules could be the carriers of the anomalous microwave emission recently detected by Watson et al. in the Perseus molecular complex.

Susana Iglesias-Groth

2005-09-15

172

Fullerenes in an impact crater on the LDEF spacecraft  

NASA Technical Reports Server (NTRS)

The fullerenes C60 and C70 have been found to occur naturally on Earth and have also been invoked to explain features in the absorption spectra of interstellar clouds. But no definitive spectroscopic evidence exists for fullerenes in space and attempts to find fullerenes in carbonaceous chondrites have been unsuccessful. Here we report the observation of fullerenes associated with carbonaceous impact residue in a crater on the Long Duration Exposure Facility (LDEF) spacecraft. Laser ionization mass spectrometry and Raman spectroscopy indicate the presence of fullerenes in the crater and in adjacent ejecta. Man-made fullerenes survive experimental hypervelocity (approximately 6.1 km s-1) impacts into aluminium targets, suggesting that space fullerenes contained in a carbonaceous micrometeorite could have survived the LDEF impact at velocities towards the lower end of the natural particle encounter range (<13 km s-1). We also demonstrate that the fullerenes were unlikely to have formed as instrumental artefacts, nor are they present as contaminants. Although we cannot specify the origin of the fullerenes with certainty, the most plausible source is the chondritic impactor. If, alternatively, the impact produced the fullerenes in situ on LDEF, then this suggests a viable mechanism for fullerene production in space.

Radicati di Brozolo, F.; Bunch, T. E.; Fleming, R. H.; Macklin, J.

1994-01-01

173

Fullerenes in an impact crater on the LDEF spacecraft.  

PubMed

The fullerenes C60 and C70 have been found to occur naturally on Earth and have also been invoked to explain features in the absorption spectra of interstellar clouds. But no definitive spectroscopic evidence exists for fullerenes in space and attempts to find fullerenes in carbonaceous chondrites have been unsuccessful. Here we report the observation of fullerenes associated with carbonaceous impact residue in a crater on the Long Duration Exposure Facility (LDEF) spacecraft. Laser ionization mass spectrometry and Raman spectroscopy indicate the presence of fullerenes in the crater and in adjacent ejecta. Man-made fullerenes survive experimental hypervelocity (approximately 6.1 km s-1) impacts into aluminium targets, suggesting that space fullerenes contained in a carbonaceous micrometeorite could have survived the LDEF impact at velocities towards the lower end of the natural particle encounter range (<13 km s-1). We also demonstrate that the fullerenes were unlikely to have formed as instrumental artefacts, nor are they present as contaminants. Although we cannot specify the origin of the fullerenes with certainty, the most plausible source is the chondritic impactor. If, alternatively, the impact produced the fullerenes in situ on LDEF, then this suggests a viable mechanism for fullerene production in space. PMID:11541208

Radicati di Brozolo, F; Bunch, T E; Fleming, R H; Macklin, J

1994-05-01

174

FULLERENIC SYSTEMS FOR NANOSCIENCE: COMPUTATIONAL SCREENING ILLUSTRATED ON X@C74 METALLOFULLERENES  

E-print Network

FULLERENIC SYSTEMS FOR NANOSCIENCE: COMPUTATIONAL SCREENING ILLUSTRATED ON X@C74 METALLOFULLERENES, AZ 85721-0041, USA ABSTRACT The objects of fullerene science - fullerenes, metallo- fullerenes & other fullerene endohedrals, and nan- otubes - are discussed in a wider context of nanoscience

Paris-Sud XI, Université de

175

Infrared spectroscopy of fullerene C60/anthracene adducts  

E-print Network

Recent Spitzer Space Telescope observations of several astrophysical environments such as Planetary Nebulae, Reflection Nebulae, and R Coronae Borealis stars show the simultaneous presence of mid-infrared features attributed to neutral fullerene molecules (i.e., C60) and polycyclic aromatic hydrocarbons (PAHs). If C60 fullerenes and PAHs coexist in fullerene-rich space environments, then C60 may easily form adducts with a number of different PAH molecules; at least with catacondensed PAHs. Here we present the laboratory infrared spectra (~2-25 um) of C60 fullerene and anthracene Dies-Alder mono- and bis-adducts as produced by sonochemical synthesis. We find that C60/anthracene Diels-Alder adducts display spectral features strikingly similar to those from C60 (and C70) fullerenes and other unidentified infrared emission features. Thus, fullerene-adducts - if formed under astrophysical conditions and stable/abundant enough - may contribute to the infrared emission features observed in fullerene-containing circu...

Garcia-Hernandez, D A; Manchado, A

2013-01-01

176

Biomedical applications of functionalized fullerene-based nanomaterials  

PubMed Central

Since their discovery in 1985, fullerenes have been investigated extensively due to their unique physical and chemical properties. In recent years, studies on functionalized fullerenes for various applications in the field of biomedical sciences have seen a significant increase. The ultimate goal is towards employing these functionalized fullerenes in the diagnosis and therapy of human diseases. Functionalized fullerenes are one of the many different classes of compounds that are currently being investigated in the rapidly emerging field of nanomedicine. In this review, the focus is on the three categories of drug delivery, reactive oxygen species quenching, and targeted imaging for which functionalized fullerenes have been studied in depth. In addition, an exhaustive list of the different classes of functionalized fullerenes along with their applications is provided. We will also discuss and summarize the unique approaches, mechanisms, advantages, and the aspect of toxicity behind utilizing functionalized fullerenes for biomedical applications. PMID:20011243

Partha, Ranga; Conyers, Jodie L

2009-01-01

177

Endohedral and exohedral hybrids involving fullerenes and carbon nanotubes.  

PubMed

Since fullerenes and carbon nanotubes (CNTs) were discovered, these materials have attracted a great deal of attention in the scientific community due to their unique structures and properties. The properties of both carbon allotropes can be modulated by chemical functionalization, and merging fullerenes and CNTs combines the electronic and optical properties of CNTs with the excellent electron acceptor characteristic of fullerenes; moreover, a synergistic effect of these hybrids can be found, as the properties of both the nanotube and the fullerene are affected by the presence of the other. In these hybrids, the fullerene can be located inside (endohedral) or outside (exohedral) the CNT and both types of hybrid have specific features. CNT-fullerene hybrids have been studied for various applications, including photovoltaics, optical limiting and flame retardancy amongst others. This review outlines the progress in research on CNT-fullerene hybrids, including endohedral and exohedral combinations, their properties, functionalization, applications and outlook. PMID:22706450

Vizuete, María; Barrejón, Myriam; Gómez-Escalonilla, María José; Langa, Fernando

2012-08-01

178

Magnetospheric ion bombardment profiles of satellites - Europa and Dione  

Microsoft Academic Search

Bombardment profiles generated by tracking ions in magnetospheric plasmas onto the surface of a satellite with a suitable description of the ion motion are used to calculate the spatial dependence across a satellite surface of the ion bombardment\\/implantation rate for satellites embedded in planetary magnetospheric plasmas. Attention is given to the results of a parameter study; a general dependency on

M. K. Pospieszalska; R. E. Johnson

1989-01-01

179

Transformation of cotton ( Gossypium hirsutum L.) via particle bombardment  

Microsoft Academic Search

Embryogenic suspension cultures of cotton (Gossypium hirsutum L.) were subjected to particle bombardment, where high density particles carrying plasmid DNA were accelerated towards the embryogenic plant cells. The plasmid DNA coating the particles encoded hygromycin resistance. One to two weeks following bombardment, embryogenic cotton cells were placed in proliferation medium containing 100 µg\\/ml hygromycin. Clumps of tissue which grew in

John J. Finer; Michael D. McMullen

1990-01-01

180

Time Dependent Spectral Emission of Proton Bombarded Aerogels.  

National Technical Information Service (NTIS)

The University of Arizona 2 MV Van de Graaff accelerated 1 MeV protons to bombard aerogel targets. The spectroscopic emission characteristics of proton bombarded aerogels 1.68 mm - 5.50 mm thick were studied, particularly the emission as a function of bom...

E. W. Marsh

1998-01-01

181

Fertile transgenic barley by particle bombardment of immature embryos  

Microsoft Academic Search

Transgenic, fertile barley (Hordeum vulgare L.) from the Finnish elite cultivar Kymppi was obtained by particle bombardment of immature embryos. Immature embryos were bombarded to the embryonic axis side and grown to plants without selection. Neomycin phosphotransferase II (NPTII) activity was screened in small plantlets. One out of a total of 227 plants expressed the transferred nptII gene. This plant

Anneli Ritala; Kristian Aspegren; Ulrika Kurtén; Marjatta Salmenkallio-Marttila; Leena Mannonen; Riitta Hannus; Veli Kauppinen; Teemu H. Teeri; Tor-Magnus Enari

1994-01-01

182

Advances in fast-atom-bombardment mass spectroscopy  

Microsoft Academic Search

A comparison of fast atom bombardment and field desorption mass spectrometry was made to determine relative sensitivity and applicability. A series of glycosphingolipids and a series of protected oligonucleotides of known structure were analyzed to ascertain the potential utility of fast atom bombardment mass spectrometry in the structural elucidation of novel compounds in these classes. Negative ion mass markers were

Hemling

1986-01-01

183

Formalism of collective electron excitations in fullerenes  

E-print Network

We present a detailed formalism for the description of collective electron excitations in fullerenes in the process of the electron inelastic scattering. Considering the system as a spherical shell of a finite width, we show that the differential cross section is defined by three plasmon excitations, namely two coupled modes of the surface plasmon and the volume plasmon. The interplay of the three plasmons appears due to the electron diffraction of the fullerene shell. Plasmon modes of different angular momenta provide dominating contributions to the differential cross section depending on the transferred momentum.

Verkhovtsev, Alexey V; Solov'yov, Andrey V

2012-01-01

184

Laser controlled magnetism in hydrogenated fullerene films  

SciTech Connect

Room temperature ferromagnetic-like behavior in fullerene photopolymerized films treated with monatomic hydrogen is reported. The hydrogen treatment controllably varies the paramagnetic spin concentration and laser induced polymerization transforms the paramagnetic phase to a ferromagnetic-like one. Excess laser irradiation destroys magnetic ordering, presumably due to structural changes, which was continuously monitored by Raman spectroscopy. We suggest an interpretation of the data based on first-principles density-functional spin-unrestricted calculations which show that the excess spin from mono-atomic hydrogen is delocalized within the host fullerene and the laser-induced polymerization promotes spin exchange interaction and spin alignment in the polymerized phase.

Makarova, Tatiana L.; Shelankov, Andrei L. [Umeaa University, 90187 Umeaa (Sweden); Ioffe Physicotechnical Inst., 194021, St. Petersburg (Russian Federation); Kvyatkovskii, Oleg E. [Ioffe Physicotechnical Inst., 194021, St. Petersburg (Russian Federation); Zakharova, Irina B. [St. Petersburg State Polytechnical University, 195251, St. Petersburg (Russian Federation); Buga, Sergei G.; Volkov, Aleksandr P. [Technological Institute for Superhard and Novel Carbon Materials, 142190, Troitsk (Russian Federation)

2011-04-15

185

Toroidal Fullerenes with the Cayley Graph Structures  

E-print Network

A central issue in molecular orbital theory is to compute the HOMO-LUMO gap of a molecule, which measures the excitability of the molecule. Thus it would be of interest to learn how to construct a molecule with the prescribed HOMO-LUMO gap. In this paper, we classify all possible structures of fullerene Cayley graphs and compute their spectrum. For any natural number $n$ not divisible by three, we show there exists an infinite family of fullerene graphs with the same HOMO-LUMO gap of size $\\frac{2\\pi}{\\sqrt{3}n}+O(n^{-2})$. Finally, we discuss how to realize those families in three dimensional space.

Kang, Ming-Hsuan

2009-01-01

186

Morphological characterization of fullerene-androsterone conjugates.  

PubMed

Here we report on the self-organization characteristics in water of two diastereomer pairs of fullerene-androsterone hybrids that have the hydrophobic C60 appendage in the A and D ring of the androsterone moiety, respectively. The morphology and particle size in aqueous solution were determined by transmission electron microscopy (TEM) and dynamic light scattering (DLS), with satisfactory agreement between both techniques. In general, these fullerene derivatives are shown to organize into spherical nano-scale structures with diameters in the ranges of 10-20 and 30-50 nm, respectively. PMID:24778962

Ruiz, Alberto; Suárez, Margarita; Martin, Nazario; Albericio, Fernando; Rodríguez, Hortensia

2014-01-01

187

Morphological characterization of fullerene-androsterone conjugates  

PubMed Central

Summary Here we report on the self-organization characteristics in water of two diastereomer pairs of fullerene–androsterone hybrids that have the hydrophobic C60 appendage in the A and D ring of the androsterone moiety, respectively. The morphology and particle size in aqueous solution were determined by transmission electron microscopy (TEM) and dynamic light scattering (DLS), with satisfactory agreement between both techniques. In general, these fullerene derivatives are shown to organize into spherical nano-scale structures with diameters in the ranges of 10–20 and 30–50 nm, respectively. PMID:24778962

Ruiz, Alberto; Suarez, Margarita; Martin, Nazario

2014-01-01

188

"Fragments of Fullerenes and Carbon Nanotubes: Designed Synthesis, Unusual Reactions, and Coordination Chemistry", John Wiley & Sons, 2011  

E-print Network

"Fragments of Fullerenes and Carbon Nanotubes: Designed Synthesis, Unusual Reactions the surfaces of fullerenes (and therefore often referred to as "fullerene fragments" or buckybowls covers all aspects related to the fullerene and nanotube fragment chemistry: current synthetic techniques

Linsley, Braddock K.

189

Feldspathic granulitic impactites and pre-final bombardment lunar evolution  

NASA Technical Reports Server (NTRS)

It is suggested that feldspathic granulitic impactites, which are characterized by a high model plagioclase content of between 70 and 80%, all formed in the period after consolidation of the lunar crust and before the final bombardment. The granulitic impactites contain essentially no KREEP component, which suggests that KREEP appeared on the lunar surface mostly after the formation of the granulitic impactites, at about the start of the final bombardment. The granulite metamorphism indicated by the matrix textures of these samples requires 1000 C temperatures for prolonged periods of time. The apparent sequence of formation is granulitic impactites before the final bombardment, crystalline-matrix breccias during the final bombardment, and vitric-matrix breccias after the final bombardment. The sequence is consistent with a described thermal model of breccia lithification and with characteristics of the decay of the meteorite flux rate.

Warner, J. L.; Phinney, W. C.; Bickel, C. E.; Simonds, C. H.

1977-01-01

190

Interaction between fullerenes and single-wall carbon nanotubes: the influence of fullerene size and electronic structure.  

PubMed

A series of fullerenes and endohedral metallofullerenes peapods have been synthesized by supercritical method in high filling rate. The interaction between SWNTs and various kinds of fullerenes (C60, C70, C78, C84) and metallofullerenes (Gd@C82, Er@C82, Ho@C82, Y@C82) has been further investigated. The slight blue shift of G-band in Raman spectra with respect to pristine SWNTs was attributed to the charge transfer from SWNTs to fullerenes cage. The obvious RBM shift strongly depended on the distance between the inner wall of the SWNTs and the fullerene cage and also partly associated with the electronic structure of the fullerene. These results indicated that the interaction between fullerenes and SWNTs, which was considered to be the van de walls interaction, can be influenced by the cage size and the kind of fullerenes. PMID:22097497

Hao, Jian; Guan, Lunhui; Guo, Xihong; Lian, Yongfu; Zhao, Shixiong; Dong, Jinquan; Yang, Shangyuan; Zhang, Hong; Sun, Baoyun

2011-09-01

191

Soluble fullerene derivative in liquid crystal: polymer composites and their impact on photorefractive  

E-print Network

Soluble fullerene derivative in liquid crystal: polymer composites and their impact 106593); published 26 March 2009 By using soluble fullerene derivative [60]PCBM, we improved crystals (PSLC with a polymer concentration fullerene

Paris-Sud XI, Université de

192

Effects of spherical fullerene nanoparticles on a dipalmitoyl phosphatidylcholine lipid monolayer: a coarse grain molecular dynamics  

E-print Network

Effects of spherical fullerene nanoparticles on a dipalmitoyl phosphatidylcholine lipid monolayer. Here, we use coarse grain molecular dynamics simulations to study spherical fullerene molecules show that all the tested fullerene molecules can spontaneously diffuse into both a lipid bilayer

Nielsen, Steven O.

193

An Infrared Study of Fullerene Planetary Nebulae  

E-print Network

We present a study of 16 PNe where fullerenes have been detected in their Spitzer spectra. This large sample of objects offers an unique opportunity to test conditions of fullerene formation and survival under different metallicity environments as we are analyzing five sources in our own Galaxy, four in the LMC, and seven in the SMC. Among the 16 PNe under study, we present the first detection of C60 (possibly also C70) fullerenes in the PN M 1-60 as well as of the unusual 6.6, 9.8, and 20 um features (possible planar C24) in the PN K 3-54. Although selection effects in the original samples of PNe observed with Spitzer may play a potentially significant role in the statistics, we find that the detection rate of fullerenes in C-rich PNe increases with decreasing metallicity (5% in the Galaxy, 20% in the LMC, and 44% in the SMC). CLOUDY photoionization modeling matches the observed IR fluxes with central stars that display a rather narrow range in effective temperature (30,000-45,000 K), suggesting a common evo...

Garcia-Hernandez, D A; Garcia-Lario, P; Acosta-Pulido, J A; Manchado, A; Stanghellini, L; Shaw, R A; Cataldo, F

2012-01-01

194

Molecular Structure of Fullerene C60  

NSDL National Science Digital Library

Three professors are credited with the discovery of fullerenes, a family of symmetrical carbon-cage molecules. Buckyball is the the most abundant and well-known carbon-cage molecule consisting of 60 carbon atoms. This huge molecule is being studied by many scientists for its ability to serve as a conductor, insulator, semiconductor, and superconductor.

2002-08-26

195

Pyrolytic and gas phase fullerene derivatization reactions  

NASA Astrophysics Data System (ADS)

The bulk production of naphthyne derivatives of [60]fullerene, C60, is achieved by pyrolysis of 1,8-diiodonaphthalene in the presence of C60. Desorption chemical ionization mass spectra, recorded in the negative ion mode, show the addition of up to ten naphthyne units to a single C60 molecule. Products containing two C60 molecules are also generated. Tandem mass spectrometry confirms that covalent bonding has occurred. Similar reactions are described for the reactive intermediates generated from 1,8-naphthalic anhydride, 9-iodoanthracene, 2,6-dimethoxyiodobenzene, 2-iodonaphthalene and hexabromobenzene. Evidence for a [4 + 2] Diels--Alder ion/molecule reaction between mass-selected fullerene cations and methoxy-substituted 1,3-butadienes is presented. Ion/molecule reactions of various closed shell cations derived from the dissociative electron ionization of chlorine containing compounds are shown to result in the methylation, acylation, phenylation and benzylation of fullerenes in the course of positive ion chemical ionization. In the negative ion mode, halogenated fullerene anions are observed. At high desorption temperatures, the addition of at least 30 hydrogen atoms to C60 is reported.

Hoke, Steven H.; Molstad, Jay; Kahr, Bart; Cooks, R. Graham

1994-10-01

196

Synthetic chemistry with fullerenes. Photooxygenation of olefins  

SciTech Connect

Under irradiation with visible or UV (>290 nm) light in the presence of molecular oxygen and a minute amount of fullerenes, olefins and dienes undergo ene and Diels-Alder reactions with singlet oxygen to give photooxygenation products. The regio-and stereoselectives of the photooxygenation of {beta}-myrcene, (+)-pulegone, 4-methylpent-3-en-2-ol, and (+)-limonene were very similiar to those observed in known singlet oxygen reactions, indicating that the fullerene-sensitized reaction generates free singlet oxygen. The efficiency of fullerenes and conventional sensitizers was qualitively examined by using the Diels-Alder reaction between {sup 1}O{sub 2} and furan-2-carboxylic acid as a probe. Among those examined, C{sub 70} was found to be the most effective. The reaction was the fastest and completed with as little as 0.0001 equiv of C{sub 70}. C{sub 60} and hematoporphyrin were found to be of similiar efficiency. The methanofullerene 13, which lacks one olefinic conjunction in the C{sub 60} core, was as good as C{sub 60} itself, but the aminofullerene 14, lacking six double bonds, was quite inferior. The fullerene carboxylic acid 15, which was previously shown to show considerable biochemical activity, was found to be capable of generating singlet oxygen in aqueous DMSO. 25 refs., 1 tab.

Tokuyama, Hidetoshi; Nakamura, Eiichi [Tokyo Institute of Technology, Merguro, Tokyo (Japan)

1994-03-11

197

C60 fullerene binding to DNA  

NASA Astrophysics Data System (ADS)

Fullerenes have attracted considerable attention in various areas of science and technology. Owing to their exceptional physical, chemical, and biological properties, they have many applications, particularly in cosmetic and medical products. Using the Lennard-Jones 6-12 potential function and the continuum approximation, which assumes that intermolecular interactions can be approximated by average atomic surface densities, we determine the binding energies of a C60 fullerene with respect to both single-strand and double-strand DNA molecules. We assume that all configurations are in a vacuum and that the C60 fullerene is initially at rest. Double integrals are performed to determine the interaction energy of the system. We find that the C60 fullerene binds to the double-strand DNA molecule, at either the major or minor grooves, with binding energies of -4.7 eV or -2.3 eV, respectively, and that the C60 molecule binds to the single-strand DNA molecule with a binding energy of -1.6 eV. Our results suggest that the C60 molecule is most likely to be linked to the major groove of the dsDNA molecule.

Alshehri, Mansoor H.; Cox, Barry J.; Hill, James M.

2014-09-01

198

TOROIDAL FULLERENES WITH THE CAYLEY GRAPH STRUCTURE  

Microsoft Academic Search

A central issue in molecular orbital theory is to compute the HOMO-LUMO gap of a molecule, which measures the excitability of the molecule. Thus it would be of interest to learn how to construct a molecule with the prescribed HOMO-LUMO gap. In this paper, we classify all possible structures of fullerene Cayley graphs and compute their spectrum. For any natural

MING-HSUAN KANG

199

Toroidal Fullerenes with the Cayley Graph Structures  

Microsoft Academic Search

A central issue in molecular orbital theory is to compute the HOMO-LUMO gap of a molecule, which measures the excitability of the molecule. Thus it would be of interest to learn how to construct a molecule with the prescribed HOMO-LUMO gap. In this paper, we classify all possible structures of fullerene Cayley graphs and compute their spectrum. For any natural

Ming-Hsuan Kang

2009-01-01

200

Potassium Auger emission by K + ion bombardment of the Ni(100) surface  

NASA Astrophysics Data System (ADS)

Angle-resolved electron energy spectra induced by bombardment of a Ni(100) monocrystal surface with 0.5-4.5 keV energy K + ions have been measured. In the case when the target is previously implanted by K + ions a peak (discrete structure) in the energy range 15 < E < 17 eV is observed. This phenomenon has been ascribed to deactivation of M 23, vacancies of the K atom formed in the symmetrical collisions of projectiles with implanted or adsorbed surface K atoms. The phenomenon of the peak splitting at the higher projectile energies has been discussed within the frame of the Doppler effect in the specific case of symmetrical K-K collisions, where both collision participants can appear as Auger electron emitters.

Terzi?, I.; Rakoc?evi?, Z.; Tos?i?, M. M.

1992-01-01

201

Modification of Polymer Materials by Ion Bombardment: Case Studies  

SciTech Connect

The paper discusses possibility of application of ion beam bombardment for modification of polymers. Changes to composition, structure and morphology of the surface layer produced by the treatment and their influence on engineering and functional properties of wide range of polymer materials are presented. Special attention has been devoted to modification of tribological properties. Ion bombardment results in significant reduction of friction, which can be explained by increase of hardness and wettability of polymer materials. Hard but thin enough skin does not result in cracking but improves their abrasion resistance. Contrary to conventional chemical treatment ion beam bombardment works even for polymers hardly susceptible to modification like silicone rubber or polyolefines.

Bielinski, D. M. [Institute of Polymer and Dye Technology, Technical University of Lodz, Stefanowskiego 12/16, 90-924 Lodz (Poland); Institute for Engineering of Polymer Materials and Dyes, Division of Elastomers and Rubber Technology, Liarcerska 30, 05-820 Piastow (Poland); Jagielski, J. [Institute for Electronic Materials Technology, Wolczynska 133, 01-919 Warsaw (Poland); The Andrzej Soltan Institute of Nuclear Studies, 05-400 Otwock/Swierk (Poland); Lipinski, P.; Pieczynska, D.; Ostaszewska, U. [Institute for Engineering of Polymer Materials and Dyes, Division of Elastomers and Rubber Technology, Liarcerska 30, 05-820 Piastow (Poland); Piatkowska, A. [Institute for Electronic Materials Technology, Wolczynska 133, 01-919 Warsaw (Poland)

2009-03-10

202

Genetic transformation of wheat via particle bombardment.  

PubMed

Since its first invention in the late 1980s the particle gun has evolved from a basic gunpowder driven machine firing tungsten particles to one more refined which uses helium gas as the propellant to launch alternative heavy metal particles such as gold and silver. The simple principle is that DNA-coated microscopic particles (microcarriers) are accelerated at high speed by helium gas within a vacuum and travel at such a velocity as to penetrate target cells. However, the process itself involves a range of parameters which are open to variation: microparticle type and size, gun settings (rupture pressure, target distance, vacuum drawn, etc.), preparation of components (e.g., gold coating), and preparation of plant tissues. Here is presented a method optimized for transformation of wheat immature embryos using the Bio-Rad PDS-1000/He particle gun to deliver gold particles coated with a gene of interest and the selectable marker gene bar at 650 psi rupture pressure. Following bombardment, various tissue culture phases are used to encourage embryogenic callus formation and regeneration of plantlets and subsequent selection using glufosinate ammonium causes suppression of non-transformed tissues, thus assisting the detection of transformed plants. This protocol has been used successfully to generate transgenic plants for a wide range of wheat varieties, both spring and winter bread wheats (T. aestivum L.) and durum wheats (T. turgidum L.). PMID:24243206

Sparks, Caroline A; Jones, Huw D

2014-01-01

203

Fullerenes C60 and C70 in flames  

Microsoft Academic Search

THE fullerenes C60 and C70 were first identified1 in carbon vapour produced by laser irradiation of graphite, and have recently been produced in macroscopic quantities2-5 by vaporization of graphite with resistive heating. It has also been suggested6-9 that fullerenes might be formed in sooting flames, and indeed all-carbon ions with mass\\/charge ratios suggestive of fullerenes have been detected in flames10-12.

Jack B. Howard; J. Thomas McKinnon; Yakov Makarovsky; Arthur L. Lafleur; M. Elaine Johnson

1991-01-01

204

Polythermal solubility of fullerenes in higher isomeric carboxylic acids  

Microsoft Academic Search

The solubility of individual fullerenes C60 and C70 and a fullerene mixture enriched in higher fullerenes (C60 38.8, C70 33.0, C76–78 5.6, C84 8.6, C90 2.6, and C96 3.3%) in higher isomeric carboxylic acids was studied within the 20–80C temperature range; the corresponding solubility\\u000a polytherms are presented.

K. N. Semenov; O. V. Arapov; A. K. Pyartman; V. A. Keskinov; V. V. Lishchuk; N. A. Charykov; N. I. Alekseev

2007-01-01

205

Production of Mg and Al Auger electrons by noble gas ion bombardment of Mg and Al surfaces  

NASA Technical Reports Server (NTRS)

Relative production efficiencies of Mg and Al Auger electrons by He, Ne, Ar, Kr, and Xe ion bombardment are reported as a function of ion energy for energies not exceeding 3 keV. The experimental apparatus employed consisted of a LEED-Auger system equipped with an ion gun and a four-grid retarding-potential analyzer. It is found that: (1) the shape of the ion-excited Auger signal was independent of the rare gas and quite symmetric; (2) the Al signal was about an order of magnitude smaller than the Mg signal for a given bombarding species and ion-gun voltage; (3) no signal was observed for He(+) bombardment under any of the experimental conditions; (4) signal strengths were independent of temperature and ion dose; (5) the Auger production efficiencies differed by no more than a factor of two among the different gases - except for He(+) - on a given metal; (6) all the signal strengths increased with increasing ion-gun voltage, with no maximum exhibited; and (7) the apparent threshold energy for the Al signal was higher than that for the Mg signal. The differences between the results for the two metals are attributed to the fact that the Al 2p orbital lies deeper in energy and closer to the nucleus than the corresponding Mg orbital.

Ferrante, J.; Pepper, S. V.

1976-01-01

206

Prevention of cathode damage from positive ion bombardment  

NASA Technical Reports Server (NTRS)

Mixed alkaline earth oxide compounds deposited into hole at cathode surface center prevent ion back bombardment damage to cathode by reducing oxide layer and by creating metallic diffusion along sides of hole for enhanced electron emission.

Bennett, W. H.

1972-01-01

207

Functional transient genetic transformation of Arabidopsis leaves by biolistic bombardment  

E-print Network

Functional transient genetic transformation of Arabidopsis leaves by biolistic bombardment Shoko, reproducible and relatively simple methodology for transient genetic transformation of Arabidopsis tissues of its complete genome sequence and wealth of genetic genomic tools and resources, which include

Citovsky, Vitaly

208

Odd cycle transversals and independent sets in fullerene graphs  

E-print Network

A fullerene graph is a cubic bridgeless plane graph with all faces of size 5 and 6. We show that that every fullerene graph on $n$ vertices can be made bipartite by deleting at most $\\sqrt{12n/5}$ edges, and has an independent set with at least $n/2-\\sqrt{3n/5}$ vertices. Both bounds are sharp, and we characterise the extremal graphs. This proves conjectures of Do\\v{s}li\\'c and Vuki\\v{c}evi\\'c, and of Daugherty. We deduce two further conjectures on the independence number of fullerene graphs, as well as a new upper bound on the smallest eigenvalue of a fullerene graph.

Faria, Luerbio; Stehlík, Mat?j

2012-01-01

209

Higher fullerenes: Compositional analysis by EDXD and molecular dynamics  

NASA Astrophysics Data System (ADS)

A carbon soot of higher fullerenes was studied by Energy Dispersive X-ray Diffraction (EDXD) aiming at defining the overall structure as accurately as possible to define the overall structure, without lengthy separation and purification procedures. EDXD pattern was compared with model curves obtained for single homogeneous fullerenes already crystallized and for the hypothesized C180. All fullerenes contribute to the overall experimental curve to different extents, with C96 giving the best agreement. The presence of even higher fullerenes is very likely, since the hypothesized C180 gives a very good match as well.

Carbone, Marilena; Gontrani, Lorenzo

2014-06-01

210

Adsorption of midmolecular peptides by fullerene modified silica gel  

NASA Astrophysics Data System (ADS)

The adsorption properties of raw and processed silica gels and of silica gels modified with fullerene (fullerene-silica gel nanosystems) toward serum midmolecular peptides of ischemic origin were examined. A high adsorption capacity of the nanosorbents was found. The influence of fullerenes on the condition of silica gel was studied by solid-state NMR, and an increase in the silanol fraction at the adsorbent surface was demonstrated. It was shown that presence of fullerene C60 in nanosorbents enables oxidation reaction of the adsorbed peptides, i.e., sorption of metabolites.

Melenevskaya, E. Yu.; Gribanov, A. V.; Podosenova, N. G.

2010-01-01

211

Generation of singlet oxygen in fullerene-containing media: 2. Fullerene-containing solutions  

SciTech Connect

The generation of singlet oxygen in fullerene solutions is studied by luminescence methods upon excitation by pulsed, repetitively pulsed, and continuous radiation sources. The concentration of singlet oxygen in solutions is measured in stationary and pulsed irradiation regimes. The rate constants of quenching of O{sub 2}({sup 1}{delta}{sub g}) by fullerenes C{sub 70} and C{sub 60} in the CCl{sub 4} solution are measured to be (7.2{+-}0.1)x10{sup 7} L mol{sup -1} s{sup -1} and less than 6x10{sup 4} L mol{sup -1} s{sup -1}, respectively. The temperature and photolytic variations in the generation properties of the fullerene solution exposed to intense continuous radiation are studied by the methods of optical and EPR spectroscopy. Pulsed irradiation resulted in the production of singlet oxygen in suspensions of fullerene-like structures, in particular, astralenes. A liquid pulsed singlet-oxygen generator based on the fullerene solution in CCl{sub 4} is developed and studied, in which the yield of O{sub 2} ({sup 1}{delta}{sub g}) to the gas phase at concentrations up to 5x10{sup 16} cm{sup -3} is obtained. (laser applications and other topics in quantum electronics)

Bagrov, I V; Belousova, I M; Grenishin, A S; Danilov, O B; Ermakov, A V; Kiselev, V M; Kislyakov, I M; Murav'eva, T D; Sosnov, E N [Institute for Laser Physics, Federal State Unitary Enterprise, Scientific and Industrial Corporation 'Vavilov State Optical Institute', St. Petersburg (Russian Federation)

2008-03-31

212

Fullerene sugar balls: a new class of biologically active fullerene derivatives.  

PubMed

Among the large variety of bioactive C60 derivatives, fullerene derivatives substituted with sugar residues, that is, glycofullerenes, are of particular interest. The sugar residues are not only solubilizing groups; their intrinsic biological properties also provide additional appealing features to the conjugates. The most recent advances in the synthesis and the biological applications of glycofullerenes are summarized in the present review article with special emphasis on globular glycofullerenes, that is, fullerene sugar balls, constructed on a hexa-substituted fullerene scaffold. The high local concentration of carbohydrates around the C60 core in fullerene sugar balls is perfectly suited to the binding of lectins through the "glycoside cluster effect", and these compounds are potential anti-adhesive agents against bacterial infection. Moreover, mannosylated fullerene sugar balls have shown antiviral activity in an Ebola pseudotyped infection model. Finally, when substituted with peripheral iminosugars, dramatic multivalent effects have been observed for glycosidase inhibition. These unexpected observations have been rationalized by the interplay of interactions involving the catalytic site of the enzyme and non-glycone binding sites with lectin-like abilities. PMID:24678063

Nierengarten, Iwona; Nierengarten, Jean-François

2014-06-01

213

Sputtering and surface structure modification of gold thin films deposited onto silicon substrates under the impact of 20-160 keV Ar+ ions  

NASA Astrophysics Data System (ADS)

The induced sputtering and surface state modification of Au thin films bombarded by swift Ar+ ions under normal incident angle have been studied over an energy range of (20-160) keV using three complementary techniques: Rutherford backscattering spectroscopy (RBS), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The sputtering yields determined by RBS measurements using a 2 MeV 4He+ ion beam were found to be consistent with previous data measured within the Ar+ ion energy region E ? 50 keV, which are thus extended to higher bombarding energies. Besides, the SEM and XRD measurements clearly point out that the irradiated Au film surfaces undergo drastic modifications with increasing the Ar+ ion energy, giving rise to the formation of increasingly sized grains of preferred (1 1 1) crystalline orientations. The relevance of different sputtering yield models for describing experimental data is discussed with invoking the observed surface effects induced by the Ar+ ion irradiation.

Mammeri, S.; Ouichaoui, S.; Ammi, H.; Dib, A.

2014-10-01

214

Transformation of Dendrobium orchid using particle bombardment of protocorms  

Microsoft Academic Search

Transformed dendrobium orchids (Dendrobium x Jaquelyn Thomas hybrids) were recovered from protocorms bombarded by particles coated with the plasmid pGA482GG\\/cpPRV4, which contains the plant expressible Nos-NPT II and papaya ringspot virus (PRV) coat protein (CP) genes. Approximately 280 protocorms from four crosses were bombarded and potentially transformed tissues were identified by growth and green color on half-strength Murashige and Skoog

Adelheid R. Kuehnle; Nellie Sugii

1992-01-01

215

Transgene inheritance in plants genetically engineered by microprojectile bombardment  

Microsoft Academic Search

Microprojectile bombardment to deliver DNA into plant cells represents a major breakthrough in the development of plant transformation\\u000a technologies and accordingly has resulted in transformation of numerous species considered recalcitrant toAgrobacterium- or protoplast-mediated transformation methods. This article attempts to review the current understanding of the molecular\\u000a and genetic behavior of transgenes introduced by microprojectile bombardment. The characteristic features of the

Wojciech P. Pawlowski; David A. Somers

1996-01-01

216

Bombardment-induced segregation and redistribution  

SciTech Connect

During ion bombardment, a number of processes can alter the compositional distribution and microstructure in near-surface regions of alloys. The relative importance of each process depends principally on the target composition, temperature, and ion characteristics. In addition to displacement mixing leading to a randomization of atomic locations, and preferential loss of alloying elements by sputtering, which are dominant at relatively low temperatures, several thermally-activated processes, including radiation-enhanced diffusion, radiation-induced segregation and Gibbsian adsorption, also play important roles. At elevated temperatures, nonequilibrium point defects induced by ion impacts become mobile and tend to anneal out by recombination and diffusion to extended sinks, such as dislocations, grain boundaries and free surfaces. The high defect concentrations, far exceeding the thermodynamic equilbrium values, can enhance diffusion-controlled processes, while persistent defect fluxes, originating from the spatial non-uniformity in defect production and annihilation, give rise to local redistribution of alloy constituents because of radiation-induced segregation. Moreover, when the alloy is maintained at high temperature, Gibbsian adsorption, driven by the reduction in free energy of the system, occurs even without irradiation; it involves a compositional perturbation in a few atom layers near the alloy surface. The combination of these processes leads to the complex development of a compositionally-modified layer in the subsurface region. In the present paper, selected examples of these different phenomena and their synergistic effects on the evolution of the near-surface compositions of alloys during sputtering and ion implantation at elevated temperatures are discussed. 74 refs., 7 figs., 1 tab.

Lam, N.Q.; Wiedersich, H.

1986-04-01

217

Explaining Fullerene Dispersion by using Micellar Solutions.  

PubMed

An effective computational strategy to describe the dispersion of C60 by surfactants is presented. The influence of parameters such as surfactant concentration and molecular length on the final morphology of the system is explored to explain the experimental results and to understand the incorporation of C60 inside micelles. Both neutral and charged amphiphilic molecules are simulated. The long-discussed problem of the location of fullerenes in micelles is addressed and C60 is found in the hydrocarbon-chain region of the micelles. If the available hydrophobic space increases, C60 is localized in the inner part of the micellar core. Short, charged amphiphilic stabilizers are more efficient at dispersing fullerenes monomolecularly. Two different phases of C60 are observed as the C60 /surfactant ratio varies. In the first, aggregates of C60 are entrapped inside the micelles, whereas, in the second, colloidal nanoC60 is formed with surfactants adsorbed on the surface. PMID:25060854

Dallavalle, Marco; Leonzio, Marco; Calvaresi, Matteo; Zerbetto, Francesco

2014-10-01

218

Carbon and fullerene nanomaterials in plant system  

PubMed Central

Both the functionalized and non functionalized carbon nanomaterials influence fruit and crop production in edible plants and vegetables. The fullerene, C60 and carbon nanotubes have been shown to increase the water retaining capacity, biomass and fruit yield in plants up to ~118% which is a remarkable achievement of nanotechnology in recent years. The fullerene treated bitter melon seeds also increase the phytomedicine contents such as cucurbitacin-B (74%), lycopene (82%), charantin (20%) and insulin (91%). Since as little as 50 ?g mL?1 of carbon nanotubes increase the tomato production by about 200%, they may be exploited to enhance the agriculture production in future. It has been observed that, in certain cases, non functionalized multi-wall carbon nanotubes are toxic to both plants and animals but the toxicity can be drastically reduced if they are functionalized. PMID:24766786

2014-01-01

219

Transport of fullerene molecules along graphene nanoribbons  

PubMed Central

We study the motion of C60 fullerene molecules and short-length carbon nanotubes on graphene nanoribbons. We reveal that the character of the motion of C60 depends on temperature: for T < 150?K the main type of motion is sliding along the surface, but for higher temperatures the sliding is replaced by rocking and rolling. Modeling of the buckyball with an included metal ion demonstrates that this molecular complex undergoes a rolling motion along the nanoribbon with the constant velocity under the action of a constant electric field. The similar effect is observed in the presence of the heat gradient applied to the nanoribbon, but mobility of carbon structures in this case depends largely on their size and symmetry, such that larger and more asymmetric structures demonstrate much lower mobility. Our results suggest that both electorphoresis and thermophoresis can be employed to control the motion of carbon molecules and fullerenes. PMID:23259049

Savin, Alexander V.; Kivshar, Yuri S.

2012-01-01

220

Diamond films grown from fullerene precursors  

SciTech Connect

Fullerene precursors have been shown to result in the growth of diamond films from argon microwave plasmas. In contradistinction to most diamond films grown using conventional methane-hydrogen mixtures, the fullerene-generated films are nanocrystalline and smooth on the nanometer scale. They have recently been shown to have friction coefficients approaching the values of natural diamond. It is clearly important to understand the development of surface morphology during film growth from fullerene precursors and to elucidate the factors leading to surface roughness when hydrogen is present in the chemical vapor deposition (CVD) gas mixtures. To achieve these goals, we are measuring surface reflectivity of diamond films growing on silicon substrates over a wide range of plasma processing conditions. A model for the interpretation of the laser interferometric data has been developed, which allows one to determine film growth rate, rms surface roughness, and bulk losses due to scattering and absorption. The rms roughness values determined by reflectivity are in good agreement with atomic force microscope (AFM) measurements. A number of techniques, including high-resolution transmission electron microscopy (HRTEM) and near-edge x-ray absorption find structure (NEXAFS) measurements, have been used to characterize the films. A mechanism for diamond-film growth involving the C{sub 2} molecule as a growth species will be presented. The mechanism is based on (1) the observation that the optical emission spectra of the fullerene- containing plasmas are dominated by the Swan bands of C{sub 2} and (2) the ability of C{sub 2} to insert directly into C-H and C-C bonds with low activation barriers, as shown by recent theoretical calculations of reactions of C{sub 2} with carbon clusters.

Gruen, D.M.; Zuiker, C.D.; Krauss, A.R.

1995-07-01

221

Pyrolytic and gas phase fullerene derivatization reactions  

Microsoft Academic Search

The bulk production of naphthyne derivatives of [60]fullerene, C60, is achieved by pyrolysis of 1,8-diiodonaphthalene in the presence of C60. Desorption chemical ionization mass spectra, recorded in the negative ion mode, show the addition of up to ten naphthyne units to a single C60 molecule. Products containing two C60 molecules are also generated. Tandem mass spectrometry confirms that covalent bonding

Steven H. Hoke; Jay Molstad; Bart Kahr; R. Graham Cooks

1994-01-01

222

Fullerenes as Photosensitizers in Photodynamic Therapy  

Microsoft Academic Search

Fullerenes are a class of closed-cage nanomaterials made exclusively from carbon atoms. A great deal of attention has been\\u000a focused on developing medical uses of these unique molecules especially when they are derivatized with functional groups to\\u000a make them soluble and therefore able to interact with biological systems. Due to their extended ?-conjugation they absorb\\u000a visible light, have a high

Pawel Mroz; George P. Tegos; Hariprasad Gali; Timothy Wharton; Tadeusz Sarna; Michael R. Hamblin

2008-01-01

223

Supramolecular ordering in oligothiophene-fullerene monolayers.  

PubMed

Scanning tunneling microscopy (STM) of monolayers comprising oligothiophene and fullerene molecular semiconductors reveals details of their molecular-scale phase separation and ordering with potential implications for the design of organic electronic devices, in particular future bulk heterojunction solar cells. Prochiral terthienobenzenetricarboxylic acid (TTBTA) self-assembles at the solution/graphite interface into either a porous chicken wire network linked by dimeric hydrogen bonding associations of COOH groups (R(2)(2) (8)) or a close-packed network linked in a novel hexameric hydrogen bonding motif (R(6)(6) (24)). Analysis of high-resolution STM images shows that the chicken wire phase is racemically mixed, whereas the close-packed phase is enantiomerically pure. The cavities of the chicken wire structure can efficiently host C60 molecules, which form ordered domains with either one, two, or three fullerenes per cavity. The observed monodisperse filling and long-range co-alignment of fullerenes is described in terms of a combination of an electrostatic effect and the commensurability between the graphite and molecular network, which leads to differentiation of otherwise identical adsorption sites in the pores. PMID:19919147

MacLeod, Jennifer M; Ivasenko, Oleksandr; Fu, Chaoying; Taerum, Tyler; Rosei, Federico; Perepichka, Dmitrii F

2009-11-25

224

Specific heat of endohedral and higher fullerene thin films K. Allen and F. Hellman  

E-print Network

Specific heat of endohedral and higher fullerene thin films K. Allen and F. Hellman Department that of C82 . Remarkably, however, C82 contrasts sharply with the other empty fullerenes in that it shows fullerenes are receiving increas- ing research attention. Encapsulating atoms inside fullerene cages

Hellman, Frances

225

Fullerene-like models for microporous carbon Peter J. F. Harris  

E-print Network

REVIEW Fullerene-like models for microporous carbon Peter J. F. Harris Received: 8 June 2012. The discovery of fullerenes and fullerene-related structures such as carbon nanotubes gave us a new perspective to that of the fullerenes. Recently, evidence in support of such a structure has been obtained using aberration

Harris, Peter J F

226

Coulomb interaction e ects on nonlinear optical response in C60, C70, and higher fullerenes  

E-print Network

Coulomb interaction e ects on nonlinear optical response in C60, C70, and higher fullerenes (Running head: Nonlinear optical response in higher fullerenes) Kikuo Harigaya Physical Science Division in the fullerene C60 and the extracted higher fullerenes { C70, C76, C78, and C84 { are theoretically investigated

Harigaya, Kikuo

227

Theory of scanning tunneling spectroscopy of fullerene peapods C. L. Kane,1,3  

E-print Network

Theory of scanning tunneling spectroscopy of fullerene peapods C. L. Kane,1,3 E. J. Mele,1,3 A. T for fullerene peapods: carbon nanotubes encapsulating molecular C60 . The interaction between tube encapsulated fullerene, with an encapsulated dimer, and with a periodic fullerene peapod lattice

Kane, Charles

228

Accurate Calculation, Prediction, and Assignment of 3 Chemical Shifts of Helium-3-Encapsulated Fullerenes and  

E-print Network

of fullerene derivatives than in parent C60 and C70 spectra. It is difficult, even impossible, to assign the 13-Encapsulated Fullerenes and Fullerene Derivatives Guan-Wu Wang,*, Xin-Hao Zhang, Huan Zhan, Qing-Xiang Guo-3 NMR chemical shifts of various 3 He-encapsulated fullerenes (3 He@Cn) and their derivatives have

Wang, Guan-Wu

229

ON THE RADICALANION SPECTRA OF FULLERENES C60 AND C70  

E-print Network

ON THE RADICALANION SPECTRA OF FULLERENES C60 AND C70 Franco Cataldo*1,2 , Susana Iglesias-Groth3 and at 933 nm were assigned to the fullerene dianion C60 2- . The electronic transition of C70 _ · occurs fullerene-amine adducts were reported. Key words: Fullerenes; C60; C70; Radical anion; Aminolysis

230

Fullerene C60: Surface Energy and Interfacial Interactions in Aqueous Systems  

EPA Science Inventory

The underlying mechanisms of fullerene-fullerene, fullerene-water, and fullerene-soil surface interactions in aqueous systems are not well understood. To advance our understanding of these interfacial interactions, the surface properties of Buckminsterfullerene (C60) and quartz s...

231

Cellular localisation of a water-soluble fullerene derivative  

Microsoft Academic Search

Fullerenes are a new class of compounds with potential uses in biology and medicine and many insights were made in the knowledge of their interaction with various biological systems. However, their interaction with organised living systems as well as the site of their potential action remains unclear. In this work, we have demonstrated that a fullerene derivative could cross the

Sarah Foley; Colin Crowley; Monique Smaihi; Claude Bonfils; Bernard F Erlanger; Patrick Seta; Christian Larroque

2002-01-01

232

Fullerenes and Noble Gases in the Murchison and Allende Meteorites  

NASA Technical Reports Server (NTRS)

In this work we report the detection of fullerenes (C60 to C250) in the Murchison and Allende meteorites. By exploiting the unique ability of these molecules to trap noble gases, we have determined that fullerene is indeed a new carrier phase for noble gases in meteorites.

Becker, Luann; Poreda, Robert J.; Bunch, Ted E.

2000-01-01

233

Fullerene derivatives as electron donor for organic photovoltaic cells  

SciTech Connect

We demonstrated the performance of unconventional, all-fullerene-based, planar heterojunction (PHJ) organic photovoltaic (OPV) cells using fullerene derivatives indene-C{sub 60} bisadduct (ICBA) and phenyl C{sub 61}-butyric acid methyl ester as the electron donors with fullerene C{sub 70} as the electron acceptor. Two different charge generation processes, including charge generation in the fullerene bulk and exciton dissociation at the donor-acceptor interface, have been found to exist in such all-fullerene-based PHJ cells and the contribution to the total photocurrent from each process is strongly dependent on the thickness of fullerene donor. The optimized 5?nm ICBA/40?nm C{sub 70} PHJ cell gives clear external quantum efficiency responses for the long-wavelength photons corresponding to the dissociation of strongly bound Frenkel excitons, which is hardly observed in fullerene-based single layer reference devices. This approach using fullerene as a donor material provides further possibilities for developing high performance OPV cells.

Zhuang, Taojun; Wang, Xiao-Feng, E-mail: xf-wang@yz.yamagata-u.ac.jp, E-mail: ziruo@yz.yamagata-u.ac.jp; Sano, Takeshi; Kido, Junji [Department of Organic Device Engineering, Graduate School of Engineering, and Research Center for Organic Electronics (ROEL), Yamagata University, Yonezawa 992-8510 (Japan)] [Department of Organic Device Engineering, Graduate School of Engineering, and Research Center for Organic Electronics (ROEL), Yamagata University, Yonezawa 992-8510 (Japan); Hong, Ziruo, E-mail: xf-wang@yz.yamagata-u.ac.jp, E-mail: ziruo@yz.yamagata-u.ac.jp [Department of Organic Device Engineering, Graduate School of Engineering, and Research Center for Organic Electronics (ROEL), Yamagata University, Yonezawa 992-8510 (Japan) [Department of Organic Device Engineering, Graduate School of Engineering, and Research Center for Organic Electronics (ROEL), Yamagata University, Yonezawa 992-8510 (Japan); Department of Materials Science and Engineering, University of California, Los Angeles, California 90095 (United States); Yang, Yang [Department of Materials Science and Engineering, University of California, Los Angeles, California 90095 (United States)] [Department of Materials Science and Engineering, University of California, Los Angeles, California 90095 (United States)

2013-11-11

234

Carbon arc production of heptagon-containing fullerene[68].  

PubMed

A carbon heptagon ring is a key unit responsible for structural defects in sp(2)-hybrized carbon allotropes including fullerenes, carbon nanotubes and graphenes, with consequential influences on their mechanical, electronic and magnetic properties. Previous evidence concerning the existence of heptagons in fullerenes has been obtained only in off-line halogenation experiments through top-down detachment of a C(2) unit from a stable fullerene. Here we report a heptagon-incorporating fullerene C(68), tentatively named as heptafullerene[68], which is captured as C(68)Cl(6) from a carbon arc plasma in situ. The occurrence of heptagons in fullerenes is rationalized by heptagon-related strain relief and temperature-dependent stability. (13)C-labelled experiments and mass/energy conservation equation simulations show that heptafullerene[68] grows together with other fullerenes in a bottom-up fashion in the arc zone. This work extends fullerene research into numerous topologically possible, heptagon-incorporating isomers and provides clues to an understanding of the heptagon-involved growth mechanism and heptagon-dependent properties of fullerenes. PMID:21829182

Tan, Yuan-Zhi; Chen, Rui-Ting; Liao, Zhao-Jiang; Li, Jia; Zhu, Feng; Lu, Xin; Xie, Su-Yuan; Li, Jun; Huang, Rong-Bin; Zheng, Lan-Sun

2011-01-01

235

Chemistry of fullerenes, novel allotropic modifications of carbon  

Microsoft Academic Search

The currently available data on the structure and reactivity of fullerenes, including the formation of metal complexes (including\\u000a optically active ones) with fullerenes as ligands, are briefly surveyed. The properties and reactions of fullerenyl radicals\\u000a and endohedral complexes are considered.

V. I. Sokolov; A. N. Nesmo

1999-01-01

236

Electronic structures and spectral properties of endohedral fullerenes  

Microsoft Academic Search

Endohedral fullerenes belong to a new class of compounds which are technologically and scientifically important owing to their unique structures and optoelectronic properties. This review focuses on theoretical calculations and spectroscopic (electronic, vibrational, and nuclear magnetic resonance (NMR)) studies of endohedral fullerenes thus far published. A theoretical background, with various computational methods used for determining energy-optimized electronic structure and calculation

Suchi Guha; Kazuo Nakamoto

2005-01-01

237

Highly nonlinear transport phenomena in fullerene based diodes  

NASA Astrophysics Data System (ADS)

Voltage-current measurements of fullerene based diodes in the temperature range between 295 - 15 K are presented. At temperatures below 95 K and at high current densities the diodes exhibit a voltage instability with a voltage hysteresis for opposite current sweep directions. This observation is interpreted with the formation of highly conductive current filaments in the fullerene film.

Matt, G. J.; Fromherz, T.; Neugebauer, H.; Sariciftci, N. S.

2005-09-01

238

Anomalous charge transport behavior of Fullerene based diodes  

NASA Astrophysics Data System (ADS)

We observed an anomalous voltage-current (V-I) characteristics of fullerene based diodes in the low temperature regime. The diodes exhibit a negative differential resistance and voltage hysteresis for opposite current sweep directions. This behavior is directly observable at temperatures below 95 K and indicates the formation of highly conductive filaments in the fullerene thin films.

Matt, G. J.; Sariciftci, N. S.; Fromherz, T.

2004-03-01

239

Common Electronic Structure and Pentagon Pairing in Extractable Fullerenes  

Microsoft Academic Search

We have found the bunching of the lowest three unoccupied states and the pentagon pairing in extractable fullerenes. These should be related to each other since lower unoccupied states are found to be spatially distributed on pentagons. In addition, the presence of both prevalent and rare structural units constituting extractable fullerenes has been revealed. A series of these findings sheds

Susumu Saito; Susumu Okada; Shin-Ichi Sawada; Noriaki Hamada

1995-01-01

240

Dielectric properties of fullerene-doped insulation liquids  

Microsoft Academic Search

The work presents the concept of C60 fullerene nanomodification of mineral insulation oil. For the research, 20 probes of oil were prepared; one pure and 19 containing different content of C60 - from 1 mg\\/1 to 512 mg\\/1. The probes were examined mainly against their tendency to electrification. To control if fullerene modifications do not deteriorate other parameters, the electrical

P. Aksamit; D. Zmarzy

2009-01-01

241

Excitation of fullerene ions during grazing scattering from a metal surface  

NASA Astrophysics Data System (ADS)

Angular distributions, fragmentation, and charge fractions are studied for grazing scattering of C60+ fullerenes with keV energies from a clean and flat Al(001) surface. At low energies for the motion along the surface normal, C60+ ions are scattered nearly elastically, whereas for larger normal energies energy loss is substantial. We compare our experimental results with classical trajectory simulations exploiting the Tersoff potential between atoms in the cluster and different types of interaction potentials for the cluster with the surface. The internal energy of scattered clusters is deduced from the analysis of fragments. We observe that the loss of kinetic energy for the motion along the surface normal is transferred to internal excitations of the cluster, whereas the energy transfer to the metal surface is negligible. The charge state distributions for scattered projectiles can be understood by a full neutralization of incident ions at the surface and subsequent delayed electron emission.

Wethekam, S.; Winter, H.

2007-09-01

242

Formation of fullerenes in H-containing Planetary Nebulae  

E-print Network

Hydrogen depleted environments are considered an essential requirement for the formation of fullerenes. The recent detection of C60 and C70 fullerenes in what was incorrectly interpreted as a hydrogen-poor Planetary Nebula (PN) seemed to confirm this picture. Here, we present strong evidence that challenges the current paradigm regarding fullerene formation, showing that it can take place in circumstellar environments containing hydrogen. We report the simultaneous detection of Polycyclic Aromatic Hydrocarbons (PAHs) and fullerenes towards C-rich and H-containing PNe belonging to environments with very different chemical histories such as our own Galaxy and the Small Magellanic Cloud. We suggest that PAHs and fullerenes may be formed by the photochemical processing of hydrogenated amorphous carbon. These observations have profound implications on our current understanding of the chemistry of large organic molecules as well as the chemical processing in space.

Garcia-Hernandez, D A; Garcia-Lario, P; Stanghellini, L; Villaver, E; Shaw, R A; Szczerba, R; Perea-Calderon, J V

2010-01-01

243

Formation of Fullerenes in H-containing Planetary Nebulae  

NASA Astrophysics Data System (ADS)

Hydrogen depleted environments are considered an essential requirement for the formation of fullerenes. The recent detection of C60 and C70 fullerenes in what was interpreted as the hydrogen-poor inner region of a post-final helium shell flash planetary nebula (PN) seemed to confirm this picture. Here, we present strong evidence that challenges the current paradigm regarding fullerene formation, showing that it can take place in circumstellar environments containing hydrogen. We report the simultaneous detection of polycyclic aromatic hydrocarbons (PAHs) and fullerenes toward C-rich and H-containing PNe belonging to environments with very different chemical histories such as our own Galaxy and the Small Magellanic Cloud. We suggest that PAHs and fullerenes may be formed by the photochemical processing of hydrogenated amorphous carbon. These observations suggest that modifications may be needed to our current understanding of the chemistry of large organic molecules as well as the chemical processing in space.

García-Hernández, D. A.; Manchado, A.; García-Lario, P.; Stanghellini, L.; Villaver, E.; Shaw, R. A.; Szczerba, R.; Perea-Calderón, J. V.

2010-11-01

244

FORMATION OF FULLERENES IN H-CONTAINING PLANETARY NEBULAE  

SciTech Connect

Hydrogen depleted environments are considered an essential requirement for the formation of fullerenes. The recent detection of C{sub 60} and C{sub 70} fullerenes in what was interpreted as the hydrogen-poor inner region of a post-final helium shell flash planetary nebula (PN) seemed to confirm this picture. Here, we present strong evidence that challenges the current paradigm regarding fullerene formation, showing that it can take place in circumstellar environments containing hydrogen. We report the simultaneous detection of polycyclic aromatic hydrocarbons (PAHs) and fullerenes toward C-rich and H-containing PNe belonging to environments with very different chemical histories such as our own Galaxy and the Small Magellanic Cloud. We suggest that PAHs and fullerenes may be formed by the photochemical processing of hydrogenated amorphous carbon. These observations suggest that modifications may be needed to our current understanding of the chemistry of large organic molecules as well as the chemical processing in space.

GarcIa-Hernandez, D. A.; Manchado, A. [Instituto de Astrofisica de Canarias, C/Via Lactea s/n, 38200 La Laguna (Spain); GarcIa-Lario, P. [Herschel Science Centre, European Space Astronomy Centre, Research and Scientific Support Department of ESA, Villafranca del Castillo, P.O. Box 50727, E-28080 Madrid (Spain); Stanghellini, L.; Shaw, R. A. [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Villaver, E. [Departamento de Fisica Teorica C-XI, Universidad Autonoma de Madrid, E-28049 Madrid (Spain); Szczerba, R. [N. Copernicus Astronomical Center, Rabianska 8, 87-100 Torun (Poland); Perea-Calderon, J. V., E-mail: agarcia@iac.e, E-mail: amt@iac.e, E-mail: Pedro.Garcia-Lario@sciops.esa.in, E-mail: shaw@noao.ed, E-mail: letizia@noao.ed, E-mail: eva.villaver@uam.e, E-mail: szczerba@ncac.torun.p, E-mail: Jose.Perea@sciops.esa.in [European Space Astronomy Centre, INSA S. A., P.O. Box 50727, E-28080 Madrid (Spain)

2010-11-20

245

Cyclocarbon coalescence: Mechanisms for tailor-made fullerene formation  

SciTech Connect

The availability of macroscopic quantities of fullerenes has resulted in a vast number of physical and chemical studies of these new materials. However, the mechanisms that lead to the formation of these spherical carbon allotropes are not well understood. Mass spectral evidence has been obtained for the size-selective growth of fullerenes through the coalescence of cyclo[n]carbons, molecular carbon allotropes consisting of monocyclic rings with n carbon atoms. Whereas coalescence of cyclo[30]carbon (cyclo-C[sub 30]) produces predominantly buckminsterfullerene (C[sub 60]), the smaller rings cyclo-C[sub 18] and cyclo-C[sub 24] preferentially produce fullerene C[sub 70] through distinct intermediates. The present studies not only provide new insights into fullerene formation mechanisms but also raise the possibility of tailoring the size distributions of fullerenes by variation of the appropriate properties of the precursors. 20 refs., 2 figs.

McElvany, S.W.; Ross, M.M. (Naval Research Lab., Washington, DC (United States)); Goroff, N.S. (Univ. of California, Los Angeles (United States)); Diederich, F. (Universitaetstrasse 16, Zuerich (Switzerland))

1993-03-12

246

[Factors influence on transformation by particle bombardment in Indica rice].  

PubMed

Four factors influence on transformation of indica rice, which were high osmotic treatment; different explant as the target tissue; pressure of rupture disk and quantity of plasmid DNA, were investigated in this experiment. High osmotic treatment of target tissue prior to and after bombardment increased 3.2-fold for Gus transient expression than control. The best treatment of high osmotic was that the target tissues were kept in the target-bed medium which contained 0.4-0.6 mol/L sorbitol and manitol each for 4 h prior to bombardment and for 16 h after bombardment. Four explants: scutellum from mature seed, young panicle, embryogenic callus and suspension cells of indica rice were tested as target explant by particle bombardment. The results of Gus transient showed that the highest expression was scutellum and for other three explants, the order from high to low was young panicle, embryogenic callus and suspension cell. Transgenic plants were obtained from all of the explants except young panicle. For the pressure of rupture disk on transformation, 1100 psi or 1300 psi of the pressure of rupture disk were best one for the transformation and higher than 1300 psi could damage the target tissue which become black and died in the following culture duration. For the quantity of plasmid DNA, the results showed that 0.83 microgram of plasmid DNA per bombardment was preferred for the transformation of indica rice. PMID:12548856

Tao, L Z; Xu, Q S; Liang, C Y; Ling, D H

2000-03-01

247

Non-aqueous capillary electrophoresis separation of fullerenes and C60 fullerene derivatives.  

PubMed

As the interest in the use of fullerene compounds in biomedical and cosmetic applications increases, so too does the need to develop methods for their determination and quantitation in such complex matrices. In this work, we studied the behavior of C60 and C70 fullerenes in non-aqueous capillary electrophoresis, as well as two C60 fullerene derivatives not previously reported by any electrophoretic method, N-methyl-fulleropyrrolidine and (1,2-methanofullerene C60)-61-carboxylic acid. The separation was performed using fused-silica capillaries with an I.D. of 50 ?m and tetraalkylammonium salts, namely tetra-n-decylammonium bromide (200 mM) and tetraethylammonium bromide (40 mM), in a solvent mixture containing 6 % methanol and 10 % acetic acid in acetonitrile/chlorobenzene (1:1?v/v) as the background electrolyte. Detection limits, based on a signal-to-noise ratio of 3:1, were calculated, and values between 1 and 3.7 mg/L were obtained. Good run-to-run and day-to-day precisions on concentration were achieved with relative standard deviation lower than 15 %. For the first time, an electrophoretic technique has been applied for the analysis of C60 fullerene in a commercial cosmetic cream. A standard addition method was used for quantitation, and the result was compared with that obtained by analyzing the same cream by liquid chromatography coupled to mass spectrometry. PMID:22526671

Astefanei, Alina; Núñez, Oscar; Galceran, M Teresa

2012-08-01

248

Diffuse interstellar bands in fullerene planetary nebulae: the fullerenes - diffuse interstellar bands connection  

NASA Astrophysics Data System (ADS)

We present high-resolution (R ~ 15 000) VLT/UVES optical spectra of two planetary nebulae (PNe; Tc 1 and M 1-20) where C60 (and C70) fullerenes have already been found. These spectra are of high quality (S/N > 300) for PN Tc 1, which permits us to search for the expected electronic transitions of neutral C60 and diffuse interstellar bands (DIBs). Surprisingly, we report the non-detection of the most intense optical bands of C60 in Tc 1, although this could be explained by the low C60 column density estimated from the C60 infrared bands if the C60 emission peaks far away from the central star. The strongest and most common DIBs in both fullerene PNe are normal for their reddening. Interestingly, the very broad 4428 Å DIB and the weaker 6309 Å DIB are found to be unusually intense in Tc 1. We also report the detection of a new broad (FWHM ~ 5 Å) unidentified band at ~6525 Å. We propose that the 4428 Å DIB (probably also the 6309 Å DIB and the new 6525 Å band) may be related to the presence of larger fullerenes (e.g., C80, C240, C320, and C540) and buckyonions (multishell fullerenes such as C60@C240 and C60@C240@C540) in the circumstellar envelope of Tc 1. Appendix A is available in electronic form at http://www.aanda.org

García-Hernández, D. A.; Díaz-Luis, J. J.

2013-02-01

249

Fullerene fine particles adhere to pollen grains and affect their autofluorescence and germination  

PubMed Central

Adhesion of commercially produced fullerene fine particles to Cryptomeria japonica, Chamaecyparis obtusa and Camellia japonica pollen grains was investigated. The autofluorescence of pollen grains was affected by the adhesion of fullerene fine particles to the pollen grains. The degree of adhesion of fullerene fine particles to the pollen grains varied depending on the type of fullerene. Furthermore, germination of Camellia japonica pollen grains was inhibited by the adhesion of fullerene fine particles. PMID:24198486

Aoyagi, Hideki; Ugwu, Charles U

2011-01-01

250

K-Ionization probability across the 460-keV12C( p, p 0) resonance  

NASA Astrophysics Data System (ADS)

We have remeasured the K-shell vacancy production probability P K across the 460-keV12C( p, p 0) resonance, previously investigated by Duinker et al. We are unable to confirm the large (˜70 %) variation of P K across the resonance, found by Duinker et al. for protons elastically scattered at 125°. Our values for the ratio P K (142°)/ P K (16°) are independent (within±20%) of the proton bombarding energy over the resonance region, in agreement with theoretical predictions by Blair and Anholt, Feagin and Kocbach, McVoy and Weidenmüller. Our average value for this ratio, equal to 0.88 ±0.06, agrees with the value 0.88 calculated by Amundsen and Aashamar.

Meyerhof, W. E.; Astner, G.; Hofmann, D.; Groeneveld, K. O.; Chemin, J. F.

1982-06-01

251

Optical anisotropy induced by ion bombardment of Ag(001)  

NASA Astrophysics Data System (ADS)

Grazing incidence ion bombardment results in the formation of nanoripples that induce an anisotropic optical reflection The evolution of the reflectance anisotropy has been monitored in situ with reflectance anisotropy spectroscopy. The Rayleigh-Rice theory (RRT) has been used to analyze the optical spectra quantitatively and provides the evolution of the average ripple period and root-mean-squared surface roughness. After an incipient phase, both the increase in the periodicity and the roughness vary roughly with the square root of the sputter time. Additional high-resolution low-energy electron diffraction (HR-LEED) measurements have been performed to characterize details of the average structure created by ion bombardment.

Everts, Frank; Wormeester, Herbert; Poelsema, Bene

2008-10-01

252

plutonium isotopic analysis in the 30 KeV to 210 KeV range  

SciTech Connect

Low-Energy Gamma-ray Spectroscopy (LEGS) is a nondestructive assay (NDA) technique developed in the 1980s. In 1999, it was modified to include a physical-based model for the energy dependent efficiency. It uses the gamma rays in the energy range from approximately 30 keV to 210 keV, except the 100-keV region. This energy region provides intense, well-separated gamma rays from the principal isotopes of plutonium. For applications involving small quantities (mg to g) of freshly separated plutonium in various chemical forms, it is ideally suited for accurate real-time or near real-time isotopic analysis. Since the last modification, LEGS has been incorporated into the FRAM code (Fixed-energy Response-function Analysis with Multiple efficiency), version 4. FRAM v4 is capable of analyzing the peaks in the whole energy range from 30 keV to 1 MeV, including the X-ray region. The new capability of analyzing the peaks in the 100-keV region greatly enhances the plutonium analysis in the 30 keV to 2 10 keV ranges of the traditional LEGS. We now can analyze both the freshly separated and aged plutonium with greater accuracy.

Vo, Duc T.; Li, T. K. (Tien K.)

2001-01-01

253

Solitonic fullerene structures in light atomic nuclei  

E-print Network

The Skyrme model is a classical field theory which has topological soliton solutions. These solitons are candidates for describing nuclei, with an identification between the numbers of solitons and nucleons. We have computed numerically, using two different minimization algorithms, minimum energy configurations for up to 22 solitons. We find, remarkably, that the solutions for seven or more solitons have nucleon density isosurfaces in the form of polyhedra made of hexagons and pentagons. Precisely these structures arise, though at the much larger molecular scale, in the chemistry of carbon shells, where they are known as fullerenes.

R. A. Battye; P. M. Sutcliffe

2000-12-21

254

Fullerenes vs fulleroids. Understanding their relative energies  

SciTech Connect

Both force-field (MMPI) and AMI (restricted and unrestricted HF) calculations are herein used to investigate the underlying reasons for the fullerene-fulleroid structural dichotomies observed in carbene, silylene, nitrene, and oxygen adducts of C[sub 60]. Via the investigation of a series of model systems, it is demonstrated that curvature actually favors the open, fulleroid structure; this effect of curvature on the norcaradiene-cycloheptatriene equilibrium is general. Strategies for the creation of 6,6-bridged fulleroids are suggested. 29 refs., 6 tabs.

Warner, P.M. (Northeastern Univ., Boston, MA (United States))

1994-11-30

255

Infrared spectroscopy of fullerene C60/anthracene adducts  

NASA Astrophysics Data System (ADS)

Recent Spitzer Space Telescope observations of several astrophysical environments such as planetary nebulae, reflection nebulae and R Coronae Borealis stars show the simultaneous presence of mid-infrared features attributed to neutral fullerene molecules (i.e. C60) and polycyclic aromatic hydrocarbons (PAHs). If C60 fullerenes and PAHs coexist in fullerene-rich space environments, then C60 may easily form adducts with a number of different PAH molecules, at least with catacondensed PAHs. Here we present the laboratory infrared spectra (˜2-25 ?m) of C60 fullerene and anthracene Diels-Alder mono- and bis-adducts as produced by sonochemical synthesis. We find that C60/anthracene Diels-Alder adducts display spectral features strikingly similar to those from C60 (and C70) fullerenes and other unidentified infrared emission features. Thus, fullerene adducts - if formed under astrophysical conditions and are stable/abundant enough - may contribute to the infrared emission features observed in fullerene-containing circumstellar/interstellar environments.

García-Hernández, D. A.; Cataldo, F.; Manchado, A.

2013-09-01

256

Anti-Influenza Activity of C60 Fullerene Derivatives  

PubMed Central

The H1N1 influenza A virus, which originated in swine, caused a global pandemic in 2009, and the highly pathogenic H5N1 avian influenza virus has also caused epidemics in Southeast Asia in recent years. Thus, the threat from influenza A remains a serious global health issue, and novel drugs that target these viruses are highly desirable. Influenza A RNA polymerase consists of the PA, PB1, and PB2 subunits, and the N-terminal domain of the PA subunit demonstrates endonuclease activity. Fullerene (C60) is a unique carbon molecule that forms a sphere. To identify potential new anti-influenza compounds, we screened 12 fullerene derivatives using an in vitro PA endonuclease inhibition assay. We identified 8 fullerene derivatives that inhibited the endonuclease activity of the PA N-terminal domain or full-length PA protein in vitro. We also performed in silico docking simulation analysis of the C60 fullerene and PA endonuclease, which suggested that fullerenes can bind to the active pocket of PA endonuclease. In a cell culture system, we found that several fullerene derivatives inhibit influenza A viral infection and the expression of influenza A nucleoprotein and nonstructural protein 1. These results indicate that fullerene derivatives are possible candidates for the development of novel anti-influenza drugs. PMID:23785493

Shoji, Masaki; Takahashi, Etsuhisa; Hatakeyama, Dai; Iwai, Yuma; Morita, Yuka; Shirayama, Riku; Echigo, Noriko; Kido, Hiroshi; Nakamura, Shigeo; Mashino, Tadahiko; Okutani, Takeshi; Kuzuhara, Takashi

2013-01-01

257

Supramolecular shape shifter: polymorphs of self-organized fullerene assemblies.  

PubMed

Studies of hierarchical supramolecular assemblies of a fullerene derivative bearing three hexadecyloxy chains (1) have been carried out in various conditions, such as different organic solvents, temperatures, and with ultrasonication. The dimensional control of the hierarchical supramolecular architectures from the fullerene derivative (1), such as spherical vesicles, fibers, nano-disks, and uncommon conical and flower-shaped assemblies, was previously achieved. Here, further morphologies such as microspheres, windmill-like sheets, baton-, maracas-, and jellyfish-like assemblies were discovered. Shape shifting of supramolecular assemblies was seen only in the case of the fullerene derivative (1). Reference derivatives bearing three eicosyloxy (2) and three dodecyloxy chains (3) never showed such polymorphs, however, these derivatives self-organized into microparticles with nano-flake outer surfaces and ultra-thin disks, respectively. The fullerene derivatives studied here formed interdigitated bilayer structures with different interspacing length. There are two essential intermolecular forces present due to fullerene or aliphatic chains. Fullerene moieties exhibit strong pi-pi interactions, while van der Waals interactions between aliphatic chains can be altered by variation of their length. Three hexadecyloxy chains at the fullerene moiety (1) were the most effective substitution pattern for stimulating supramolecular shape shifting. PMID:19441348

Nakanishi, Takashi; Wang, Jiaobing; Möhwald, Helmuth; Kurth, Dirk G; Michinobu, Tsuyoshi; Takeuchi, Masayuki; Ariga, Katsuhiko

2009-01-01

258

Partitioning and solubility of C60 fullerene in lipid membranes  

NASA Astrophysics Data System (ADS)

Carbon nanoparticles (CNPs) are considered to be among the most promising nanomaterials, with applications in many different areas of technology. Most CNPs can enter both artificial lipid membranes and living cells, and are biologically active. The interaction of CNPs with lipid membranes is of great interest because biological activity requires crossing or breaking lipid membranes. Moreover, lipid bilayers have been proposed to be efficient solubilizing agents for C60 and C70 fullerenes. In this comment, we review the literature on fullerene partitioning and dispersion in lipid membranes, considering both the experimental and the simulation literature, and highlighting similarities and differences. Both experiments and simulations confirm that fullerenes partition to the membrane interior, although experimental information on the location of fullerene molecules is only qualitative. On the other hand, the fullerene dispersion state is difficult to assess experimentally, and appears to depend on the details of the methodology used for the preparation of fullerene-loaded liposomes. Although some degree of aggregation is confirmed by most experiments, the extent of the aggregation is uncertain. Large aggregates observed in the presence of lipid membranes are unlikely to be found within the membrane, as they are orders of magnitude larger than the membrane thickness. Simulations carried out so far yielded contrasting results. Both atomistic and some coarse-grained simulations indicated that fullerene dimerization in lipid membranes should be significantly less favorable than that in bulk alkanes, but the physical reasons for this are still unclear.

Rossi, G.; Barnoud, J.; Monticelli, L.

2013-05-01

259

On the Excitation and Formation of Circumstellar Fullerenes  

NASA Astrophysics Data System (ADS)

Recently, we reported the first detection of fullerenes (C60, C70) in space, specifically in Tc1, a young planetary nebulae (PNe). Once injected into the ISM, these stable species survive and are thus probably widespread in the Galaxy where they contribute to interstellar extinction, heating processes, and complex chemical reactions. Following our discovery, fullerenes have now been detected in a wide range of sources (post-AGBs, PNe, reflection nebula, HII regions, H-poor stars, and YSOs), showing that when conditions are favorable, fullerenes are formed in large quantities. The challenge resides now in determining its excitation mechanisms (fluorescence vs. thermal), as this sets their diagnostic value. To this end we have analyzed the mid-IR spectrum of three fullerene-rich PNe Tc1, SMP SMC 16, and SMP LMC 56 and compared them with thermal and fluorescence models. The strength of the fullerene bands in the three planetary nebulae is very similar, while the strength of the radiation field, is markedly different. Additionally, the spatial profile of different dust components in Tc1 indicates that the fullerene emission (C60) peaks far away from the central source. All this is hard to reconcile with a thermal origin for the fullerene excitation, and thus favors fluorescence as the excitation mechanism. In addition, the spectra in the three PNe show a strong broad plateau with substructure in the 6-9um range, and which is likely related to the fullerene formation mechanism. We present model spectra for 3 nm radius HAC particles and show that these can reproduce the 6-9um plateau, which may imply that fullerenes are formed by photo-chemical processing of hydrogenated amorphous carbon (HAC) nano-particles.

Bernard-Salas, Jeronimo; Cami, J.; Peeters, E.; Jones, A. P.; Micelotta, E.; Groenewegen, M. A.

2013-01-01

260

Noncovalent endo-binding of fullerenes to diprotonated bisporphyrins.  

PubMed

Noncovalent binding of fullerenes to bisporphyrins was studied in the gas phase by energy-dependent collision-induced dissociation (CID) with Xe under single-collision conditions. The electrospray ionization mass spectra of calix[4]arene-linked bisporphyrins show that bisporphyrins take up to 3-4 protons, depending on the type of meso-substituents. Of the protonated bisporphyrins, the diprotonated species form stable 1:1 complexes with fullerenes (C(60) and C(70)). CID cracking patterns of the diprotonated bisporphyrins indicate that each monomeric porphyrin moiety is singly protonated. CID yield-energy curves obtained from the 1:1 diprotonated bisporphyrin-fullerene complexes suggest that a fullerene occupies the endo-binding site intercalated between the two singly protonated porphyrin moieties. In the cases of 1:2 diprotonated bisporphyrin-fullerene complexes, CID results show that one fullerene binds inside (endo-binding) and the other outside (exo-binding). The exo-binding mode is energetically almost identical to the binding of fullerenes to singly protonated porphyrin monomers. The endo-binding energy is at least twice the exo-binding energy. To gain insights into the binding mode, we optimized structures of diprotonated bisporphyrins and their 1:1 endo-complexes with fullerenes, and calculated the endo-binding energy for C(60), C(70) (end-on), and C(70) (side-on). The endo-binding of fullerenes to diprotonated bisporphyrins nearly doubles the ?-? interactions while reducing the electrostatic repulsion between the two singly protonated porphyrin moieties. The side-on binding of C(70) is favored over the end-on binding because the former exerts less steric strain to the lower rim of calixarene. PMID:21993661

Jung, Sunghan; van Paauwe, John D; Boyd, Peter D W; Shin, Seung Koo

2011-12-01

261

Communication: Fullerene resolution by the magnetic circular dichroism  

NASA Astrophysics Data System (ADS)

The similarity in shape makes separation and identification of fullerenes difficult. In this work, the magnetic circular dichroism (MCD) spectroscopy is presented as a useful tool for this purpose. Experimental C60 and C70 spectra were obtained and reproduced with the aid of density functional computations and the complex polarization propagator method. Theoretical spectra of other fullerenes revealed distinctive patterns extremely sensitive to molecular structure as well. Requiring tiny amounts of the sample, the MCD technique thus appears as a useful for detailed fullerene studies.

Št?pánek, Petr; Straka, Michal; Andrushchenko, Valery; Bou?, Petr

2013-04-01

262

Communication: fullerene resolution by the magnetic circular dichroism.  

PubMed

The similarity in shape makes separation and identification of fullerenes difficult. In this work, the magnetic circular dichroism (MCD) spectroscopy is presented as a useful tool for this purpose. Experimental C60 and C70 spectra were obtained and reproduced with the aid of density functional computations and the complex polarization propagator method. Theoretical spectra of other fullerenes revealed distinctive patterns extremely sensitive to molecular structure as well. Requiring tiny amounts of the sample, the MCD technique thus appears as a useful for detailed fullerene studies. PMID:23614405

Št?pánek, Petr; Straka, Michal; Andrushchenko, Valery; Bou?, Petr

2013-04-21

263

Spontaneous formation and stability of small GaP fullerenes  

E-print Network

We report the spontaneous formation of a GaP fullerene cage in ab-initio Molecular Dynamics simulations starting from a bulk fragment. A systematic study of the geometric and electronic properties of neutral and ionized GaP clusters suggests the stability of hetero-fullerenes formed by a compound with zincblend bulk structure. We find that GaP fullerenes up to 28 atoms have high symmetry, closed electronic shells, large HOMO-LUMO energy gaps and do not dissociate when ionized. We compare our results for GaP with those obtained by other groups for the corresponding BN clusters.

Tozzini, V; Fasolino, A

2000-01-01

264

A Catalog of Diffuse Interstellar Bands in Fullerene-Containing Planetary Nebulae  

NASA Astrophysics Data System (ADS)

Large fullerenes and fullerene-based molecules have been proposed as carriers of diffuse interstellar bands (DIBs). The recent detection of the most common fullerenes (C60 and C70) around some Planetary Nebulae (PNe) now enable us to study the DIBs in fullerene-rich space environments. We have studied the presence of DIBs in the optical spectra (~3300-9400 Å) of two fullerene-containing PNe (Tc 1 and M 1-20). Special attention is given to DIBs which are found to be unusually intense in fullerene-containing PNe; several of these DIBS have not previously been reported. Fullerenes larger than C60 (and C70) and multishell fullerenes may be possible candidate carriers for the unusual DIBs seen in fullerene-rich environments.

Manchado, A.; Díaz-Luis, J. J.; García-Hernández, D. A.; Cataldo, F.

2014-02-01

265

Parameterization of the fullerene coarse-grained model We parameterized a coarse-grained fullerene consistent with the MARTINI coarse-grained force field  

E-print Network

1 Parameterization of the fullerene coarse-grained model We parameterized a coarse-grained fullerene consistent with the MARTINI coarse-grained force field for lipids1 and proteins2 . In the MARTINI. For fullerene, this means mapping approximately 4 carbons to 1 coarse-grained particle. An initial approximation

Wong-Ekkabut, Jirasak

266

Compositional Evolution of Saturn's Rings Due to Meteoroid Bombardment  

Microsoft Academic Search

In this paper we address the question of compositional evolution in planetary ring systems subsequent to meteoroid bombardment. The huge surface area to mass ratio of planetary rings ensures that this is an important process, even with current uncertainties on the meteoroid flux. We develop a new model which includes both direct deposition of extrinsic meteoritic “pollutants” and ballistic transport

Jeffrey N. Cuzzi; Paul R. Estrada

1998-01-01

267

Advances in fast-atom-bombardment mass spectroscopy  

SciTech Connect

A comparison of fast atom bombardment and field desorption mass spectrometry was made to determine relative sensitivity and applicability. A series of glycosphingolipids and a series of protected oligonucleotides of known structure were analyzed to ascertain the potential utility of fast atom bombardment mass spectrometry in the structural elucidation of novel compounds in these classes. Negative ion mass markers were also developed. Fast atom bombardment was found to be one-to-two orders of magnitude more sensitive than field desorption based on the analysis of a limited number of compounds from several classes. Superior sensitivity was not universal and field desorption was clearly better in certain cases. In the negative ion mode in particular, fast atom bombardment was found to be a useful tool for the determination of the primary structure of glycosphingolipids and oligonucleotides. Carbohydrate sequence and branching information, and a fatty acid and lipid base composition were readily obtained from the mass spectra of glycosphingolipids while bidirectional nucleotide sequence, nucleotide base, and protecting group assignments were obtained for oligonucleotides. Based on this knowledge, a tentative structure of a human peripheral nervous system glycosphingolipid implicated in certain cases of disorders such as amyotrophic lateral sclerosis, Lou Gehrig's Disease, was proposed. Suitable negative ion mass markers were found in dispersions of poly(ethylene) and poly(propylene)glycols in a triethylenetetramine matrix, a matrix which also proved useful in the analysis of glycosphingolipids. These polyglycol dispersions provided ions for calibration to 2300 daltons.

Hemling, M.E.

1986-01-01

268

Brugia malayi: transient transfection by microinjection and particle bombardment  

E-print Network

Brugia malayi: transient transfection by microinjection and particle bombardment Tarig B. Higazi of the microinjected adult parasites, and in the sub-cuticular tissues of biolistically transfected adult female parasites. A similar pattern of GFP expression to that seen in the SL promoter construct transfected

Davis, Richard E.

269

RADIATIVE RECOMBINATION IN GERMANIUM CRYSTALS SUBJECTED TO FAST ELECTRON BOMBARDMENT  

Microsoft Academic Search

Data on the infrared spectrum accompanying the recombination of ; electrons and holes in germanium single crystals are presented. It is shown that ; with increase of the concentration of Frenkel defects caused by fast electron ; bombardment the relative intensity of the emission band with a maximum at 2.35 mu ; also increases. (auth);

V. S. Vavilov; A. A. Gippius; M. M. Gorshkov; B. D. Kopylovskii

1959-01-01

270

JOVIAN EARLY BOMBARDMENT: PLANETESIMAL EROSION IN THE INNER ASTEROID BELT  

SciTech Connect

The asteroid belt is an open window on the history of the solar system, as it preserves records of both its formation process and its secular evolution. The progenitors of the present-day asteroids formed in the Solar Nebula almost contemporary to the giant planets. The actual process producing the first generation of asteroids is uncertain, strongly depending on the physical characteristics of the Solar Nebula, and the different scenarios produce very diverse initial size-frequency distributions (SFDs). In this work, we investigate the implications of the formation of Jupiter, plausibly the first giant planet to form, on the evolution of the primordial asteroid belt. The formation of Jupiter triggered a short but intense period of primordial bombardment, previously unaccounted for, which caused an early phase of enhanced collisional evolution in the asteroid belt. Our results indicate that this Jovian Early Bombardment caused the erosion or the disruption of bodies smaller than a threshold size, which strongly depends on the SFD of the primordial planetesimals. If the asteroid belt was dominated by planetesimals less than 100 km in diameter, the primordial bombardment would have caused the erosion of bodies smaller than 200 km in diameter. If the asteroid belt was instead dominated by larger planetesimals, the bombardment would have resulted in the destruction of bodies as big as 500 km.

Turrini, D.; Coradini, A.; Magni, G., E-mail: diego.turrini@ifsi-roma.inaf.it [Istituto di Astrofisica e Planetologia Spaziali, INAF-IAPS, Via Fosso del Cavaliere 100, 00133, Rome (Italy)

2012-05-01

271

Self sputtering yields of silver under bombardment with polyatomic projectiles  

E-print Network

.elsevier.com/locate/nimb #12;computer (MD) simulations that have been carried out for various cluster projectiles and surfaces of motion are integrated numerically for all atoms of the system, i.e. for the projectile constituentsSelf sputtering yields of silver under bombardment with polyatomic projectiles A. Duvenbeck, M

Wucher, Andreas

272

Synthesis and Functions of Fullerene Nanotubes  

NASA Astrophysics Data System (ADS)

Fullerene nanotubes (FNTs) are the tubular needle-like crystals with diameters less than 1 ?m that are composed of fullerene molecules such as C60 and C70. Single crystalline FNTs can be synthesized by use of the liquid-liquid interfacial precipitation method. Up to now, C60 nanotubes, C70 nanotubes, and C60-C70 two-component nanotubes (NTs) have been synthesized. The as-grown C60 and C70 nanotubes have solvated hexagonal structures and turn to face-centered cubic structures by losing solvent molecules upon drying. The C60 molecules of dried C60 nanotubes are bonded via weak van der Waals forces. The C60 nanotubes decompose at about 416°C in air, showing a high thermal stability. Various materials can be incorporated into the FNTs owing to their relatively large inner diameter on the order of 100 nm. The FNTs will find various applications in the field of transistors, solar cells, catalysts, chemical synthesis templates, MEMS devices, and so forth in future.

Miyazawa, Kun'ichi

273

Fullerene synthesis by laser pyrolysis of hydrocarbons  

NASA Astrophysics Data System (ADS)

A novel route for the synthesis of carbon soots containing fullerenes has been developed i.e. the pyrolysis of hydrocarbons in gas, vapour or aerosol phase, which are heated and decomposed through the absorption of IR photons emitted by a high power CW CO2 laser. Hydrocarbons such as benzene (+ cyclopentadiene), acetylene or ethylene have been tested, pure or mixed with an oxidizer agent (nitrous oxide or oxygen) and/or a sensitizer (sulfur hexafluoride). The fullerenes were identified in the soots obtained by using as precursor the benzene/oxygen or acetylene/oxygen mixture. When these compounds are produced in significant amounts they can be detected directly in the as-formed soots by Fourier Transform Infrared Spectroscopy (FTIR). For small quantities, a Soxhlet extraction procedure is necessary and the extracts are characterized by FTIR and by other methods which are more sensitive, like mass spectrometry or High Performance Liquid Chromatography (HPLC) coupled with ultraviolet-visible spectroscopy. The influence of the operating conditions is discussed.

Armand, X.; Herlin, N.; Voicu, I.; Cauchetier, M.

1997-11-01

274

Characterization and Quantification of Biological Surfaces Using Cluster ToF-SIMS with the Event-By-Event Bombardment/Detection Mode  

E-print Network

+) do at the same impact energy.10 In 2003, Vickerman?s group developed a C601,2+ effusion source operated with a total impact energy of ~10?15 keV that greatly increases the secondary ion yields in the mass range (at m/z 400?2500, gramicidin A, PET... of gramicidin bombarded with Au400+4 was reported as ~1000 times higher than that obtained with Au+. A high energy massive gold cluster source equipped with a time-of- flight (ToF) mass spectrometer has been developed by Della Negra at the Institut de...

Chen, Li-Jung

2012-07-16

275

42nd Bombardment Squadron (Heavy). Monthly Squadron Histories and Documents, April 1945 - November 1945  

E-print Network

42nd Bombardment Squadron (H) Monthly Squadron Histories and Documents April 1945 ? November 1945. 42nd Bombardment Squadron (H), 11th Bombardment Group (H), 7th Air Force (1941-January 1943); 13th Air Force (January 1943... - ) Air Force Historical Association, IRIS No. 44028. This copy of the missions of the 42nd Bombardment Squadron was digitized from the microfilm copy (Air Force Historical Association, IRIS No. 44028) obtained from the Air Force Historical...

United States Army Air Corps

1946-01-01

276

42nd Bombardment Squadron (Heavy). Monthly Squadron Histories and Documents, February 1944 - March 1945  

E-print Network

42nd Bombardment Squadron (H) Monthly Squadron Histories and Documents February 1944 ? March 1945. 42nd Bombardment Squadron (H), 11th Bombardment Group (H), 7th Air Force (1941-January 1943); 13th Air Force (January 1943... - ) Air Force Historical Association, IRIS No. 44028. This copy of the missions of the 42nd Bombardment Squadron was digitized from the microfilm copy (Air Force Historical Association, IRIS No. 44028) obtained from the Air Force Historical...

United States Army Air Corps

1946-01-01

277

42nd Bombardment Squadron (Heavy). Monthly Squadron Histories and Documents, December 1944 - January 1945  

E-print Network

42nd Bombardment Squadron (H) Monthly Squadron Histories and Documents December 1944 ? January 1945. 42nd Bombardment Squadron (H), 11th Bombardment Group (H), 7th Air Force (1941-January 1943); 13th Air Force (January 1943... - ) Air Force Historical Association, IRIS No. 44028. This copy of the missions of the 42 nd Bombardment Squadron was digitized from the microfilm copy (Air Force Historical Association, IRIS No. 44028) obtained from the Air Force Historical...

United States Army Air Corps

1946-01-01

278

42nd Bombardment Squadron (Heavy). Monthly Squadron Histories and Documents, April 1944 - November 1944  

E-print Network

42nd Bombardment Squadron (H) Monthly Squadron Histories April 1944 ? November 1944. 42nd Bombardment Squadron (H), 11th Bombardment Group (H), 7th Air Force (1941-January 1943); 13th Air Force (January 1943... - ) Air Force Historical Association, IRIS No. 44028. This copy of the missions of the 42 nd Bombardment Squadron was digitized from the microfilm copy (Air Force Historical Association, IRIS No. 44028) obtained from the Air Force Historical...

United States Army Air Corps

1946-01-01

279

42nd Bombardment Squadron (Heavy). Monthly Squadron Histories and Documents, 18 July 1942- 7 February 1943  

E-print Network

42nd Bombardment Squadron (H) Missions: 18 July 1942 ? 7 February 1943. 42nd Bombardment Squadron (H), 11th Bombardment Group (H), 7th Air Force (1941-January 1943); 13th Air Force (January 1943 - ) Air Force Historical... Association, IRIS No. 44028. Mission Reports, 18 July 1942 ? 10 August 1943. This copy of the missions of the 42nd Bombardment Squadron was digitized from the microfilm copy (Air Force Historical Association, IRIS No. 44028) obtained from...

United States Army Air Corps

1946-01-01

280

42nd Bombardment Squadron (Heavy). Monthly Squadron Histories and Documents, 1 May 1946 - 31 July 1946  

E-print Network

42nd Bombardment Squadron (H) Monthly Squadron Histories and Documents 1 May 1946 ? 31 July 1946. 42nd Bombardment Squadron (H), 11th Bombardment Group (H), 7th Air Force (1941-January 1943); 13th Air Force (January 1943... - ) Air Force Historical Association, IRIS No. 44028. This copy of the missions of the 42 nd Bombardment Squadron was digitized from the microfilm copy (Air Force Historical Association, IRIS No. 44028) obtained from the Air Force Historical...

United States Army Air Corps; United States Army Air Corps

1946-01-01

281

42nd Bombardment Squadron (Heavy). Monthly Squadron Histories and Documents, 5 March 1944 - 18 August 1944  

E-print Network

42nd Bombardment Squadron (H) Missions: 5 March 1944 ? 18 August 1944. 42nd Bombardment Squadron (H), 11th Bombardment Group (H), 7th Air Force (1941-January 1943); 13th Air Force (January 1943 - ) Air Force... Historical Association, IRIS No. 44028. This copy of the missions of the 42 nd Bombardment Squadron was digitized from the microfilm copy (Air Force Historical Association, IRIS No. 44028) obtained from the Air Force Historical Association, Maxwell...

United States Army Air Corps

1946-01-01

282

42nd Bombardment Squadron (Heavy). Monthly Squadron Histories and Documents, 20 May 1943 - 5 March 1944  

E-print Network

42nd Bombardment Squadron (H) Missions: 20 May 1943 ? 5 March 1944. 42nd Bombardment Squadron (H), 11th Bombardment Group (H), 7th Air Force (1941-January 1943); 13th Air Force (January 1943 - ) Air Force Historical... Association, IRIS No. 44028. Mission Reports, 18 July 1942 ? 10 August 1943. This copy of the missions of the 42 nd Bombardment Squadron was digitized from the microfilm copy (Air Force Historical Association, IRIS No. 44028) obtained from the Air...

United States Army Air Corps

1946-01-01

283

Enhancing fullerene-based solar cell lifetimes by addition of a fullerene dumbbell.  

PubMed

Cost-effective, solution-processable organic photovoltaics (OPV) present an interesting alternative to inorganic silicon-based solar cells. However, one of the major remaining challenges of OPV devices is their lack of long-term operational stability, especially at elevated temperatures. The synthesis of a fullerene dumbbell and its use as an additive in the active layer of a PCDTBT:PCBM-based OPV device is reported. The addition of only 20?% of this novel fullerene not only leads to improved device efficiencies, but more importantly also to a dramatic increase in morphological stability under simulated operating conditions. Dynamic secondary ion mass spectrometry (DSIMS) and TEM are used, amongst other techniques, to elucidate the origins of the improved morphological stability. PMID:25264304

Schroeder, Bob C; Li, Zhe; Brady, Michael A; Faria, Gregório Couto; Ashraf, Raja Shahid; Takacs, Christopher J; Cowart, John S; Duong, Duc T; Chiu, Kar Ho; Tan, Ching-Hong; Cabral, João T; Salleo, Alberto; Chabinyc, Michael L; Durrant, James R; McCulloch, Iain

2014-11-17

284

Evolution of SiC Nanocluster from Carbon Fullerene: A Density Functional Theoretic Study  

SciTech Connect

Stability of SiC fullerene type structures is still an unsolved issue as no experimental confirmation has been reported so far regarding its existence. However, theoretical reports are available in the literature where carbon fullerenes were taken as base models for SiC fullerene structures. In this present Letter we show by a systematic study on the C{sub 20} fullerene that this approach may not always produce the ground state structure in fullerene form. Instead, the energetically favorable structure could be highly distorted and open structure. However, we observed a very systematic linear trend in the evolution of binding energies of SiC clusters from the carbon fullerene.

Huda, M. N.; Ray, A. K.

2008-01-01

285

Phase equilibria in the fullerene C60-fullerene C70-hexane- o-xylene-dimethylformamide system  

Microsoft Academic Search

The phase diagram of the hexane- o-xylene-dimethylformamide ternary liquid system was studied at T = 298.15 K. The diagram contained the regions of homogeneous solutions and two-phase liquid systems (systems with stratification), phase I being enriched in dimethylformamide and phase II, in hexane. The distribution of fullerenes C60 and C70 was considered at various concentrations and simultaneous presence in sections

V. A. Keskinov; A. K. Pyartman; N. A. Charykov; O. V. Arapov; A. A. Pronkin; V. V. Lishchuk; V. V. Leonov

2008-01-01

286

Phase equilibria in the fullerene C 60 -fullerene C 70 -hexane- o -xylene-dimethylformamide system  

Microsoft Academic Search

The phase diagram of the hexane-o-xylene-dimethylformamide ternary liquid system was studied at T = 298.15 K. The diagram contained the regions of homogeneous solutions and two-phase liquid systems (systems with stratification),\\u000a phase I being enriched in dimethylformamide and phase II, in hexane. The distribution of fullerenes C60 and C70 was considered at various concentrations and simultaneous presence in sections at

V. A. Keskinov; A. K. Pyartman; N. A. Charykov; O. V. Arapov; A. A. Pronkin; V. V. Lishchuk; V. V. Leonov

2008-01-01

287

Theoretical simulations of atomic and polyatomic bombardment of an organic overlayer on a metallic substrate  

Microsoft Academic Search

Our previous molecular dynamics simulations on initial test systems have laid the foundation for understanding some of the effects of polyatomic bombardment. In this paper, we describe simulations of the bombardment of a more realistic model system, an overlayer of sec-butyl-terminated polystyrene tetramers on a Ag{111} substrate. We have used this model system to study the bombardment with Xe and

K. D. Krantzman; R. Fenno; A. Delcorte; B. J. Garrison

2003-01-01

288

Fullerene-Encapsulated Atoms in the Light of Synchrotron Radiation  

SciTech Connect

Mass-selected beams of endohedral fullerene Ce-C{sub 82}{sup +} ions, of atomic Ce{sup q+} ions (q = 2, 3, 4), and of empty fullerene-cage C{sub 82}{sup +} ions were employed to study photoionization of fullerene-encapsulated and free cerium atoms. The Ce 4d inner-shell contributions to single and double ionization of the endohedral Ce-C{sub 82}{sup +} fullerene have been extracted from the data and compared with expectations based on theory and the experiments with atomic Ce ions. Dramatic reduction and redistribution of the ionization contributions to Ce 4d photoabsorption is observed. More than half of the Ce 4d oscillator strength is apparently diverted to additional decay channels of the Ce-C{sub 82}{sup +} complex.

Mueller, A.; Schippers, S. [Institut fuer Atom- und Molekuelphysik, Justus-Liebig-Universitaet, 35392 Giessen (Germany); Esteves, D. [Department of Physics, MS 220, University of Nevada, Reno, NV 89557-0058 (United States); Advanced Light Source, Lawrence Berkeley National Laboratory, MS 7-100, Berkeley, CA 94720 (United States); Habibi, M.; Phaneuf, R. A. [Department of Physics, MS 220, University of Nevada, Reno, NV 89557-0058 (United States); Kilcoyne, A. L. D.; Aguilar, A. [Advanced Light Source, Lawrence Berkeley National Laboratory, MS 7-100, Berkeley, CA 94720 (United States); Dunsch, L. [Leibniz-Institut fuer Festkoerper- und Werkstoffforschung Dresden, D-01171 Dresden (Germany)

2009-12-03

289

Role of Conformation in - Interactions and Polymer/Fullerene Miscibility  

SciTech Connect

The origin of the miscibility between C60 fullerene and a series of phenylic vinyl polymers has been investigate using a combination of wide-angle x-ray (WAXS) and neutron (WANS) scattering and density functional theory (DFT) computational modeling. The solubility limit of the C60 in the polymers was found to increase non-linearly with increasing phenylic groups in the side-chain from 1 wt% in polystyrene (PS) to 12 wt% in poly(9-vinyl phenanthrene) (P9VPh). The DFT calculations showed that the polymer interacts with the fullerene preferentially with the phenylic groups in these vinyl polymers. However, due to the backbone these phenyl groups are unable to form the energetically favorable T-junction or planar - stacks with the fullerene, and are randomly oriented to the cage. The non-linear increase in solubility is believed to be associated with shape conformity of the three ring phenanthrene to the curvature of the fullerene.

Sumpter, Bobby G [ORNL; Bucknall, David G. [Georgia Institute of Technology; Thio, Yonathan S [ORNL; Gurun, Bilge [Georgia Institute of Technology; Campbell, Katie [Georgia Institute of Technology

2011-01-01

290

Nanotribological performance of fullerene-like carbon nitride films  

NASA Astrophysics Data System (ADS)

Fullerene-like carbon nitride films exhibit high elastic modulus and low friction coefficient. In this study, thin CNx films were deposited on silicon substrate by DC magnetron sputtering and the tribological behavior at nanoscale was evaluated using an atomic force microscope. Results show that CNx films with fullerene-like structure have a friction coefficient (CoF ? 0.009-0.022) that is lower than amorphous CNx films (CoF ? 0.028-0.032). Analysis of specimens characterized by X-ray photoelectron spectroscopy shows that films with fullerene-like structure have a higher number of sp3 CN bonds and exhibit the best mechanical properties with high values of elastic modulus (E > 180 GPa) and hardness (H > 20 GPa). The elastic recovery determined on specimens with a fullerene-like CNx structure was of 95% while specimens of amorphous CNx structure had only 75% elastic recovery.

Flores-Ruiz, Francisco Javier; Enriquez-Flores, Christian Ivan; Chiñas-Castillo, Fernando; Espinoza-Beltrán, Francisco Javier

2014-09-01

291

Substantial reduction of Stone-Wales activation barrier in fullerene  

E-print Network

Stone-Wales (SW) transformation is a key mechanism responsible for the growth, transformation, and fusion in fullerenes, carbon nanotubes, and other carbon nanostructures. These topological defects also substantially alter ...

Kabir, Mohammad Mukul

292

High Resolution Laboratory Spectroscopy of Fullerenes in Support of SOFIA  

NASA Astrophysics Data System (ADS)

Our objective is to obtain the first high-resolution (rotationally-resolved) absorption rotation- vibration spectrum of gas phase C60 and C70 in the mid infrared. The gas phase fullerenes will be prepared at low temperature using a supersonic expansion of a supercritical fluid (mixture of CO2 and toluene) containing dissolved fullerenes. The samples will be probed using a widely tunable but narrow linewidth external-cavity quantum cascade laser, along with the high sensitivity technique of high-repetition-rate cavity ringdown spectroscopy. This work is intended to support (and, indeed, enable) spectroscopy of interstellar fullerenes using the EXES high-resolution spectrometer on SOFIA. While interstellar fullerenes have been widely reported in emission through low-resolution spectroscopy with Spitzer, high-resolution absorption spectroscopy with EXES/SOFIA would provide more detailed information about their column density and excitation. This, in turn, would provide important insight into the production of these large carbonaceous molecules.

McCall, Benjamin

293

The mechanism of oxidation of fullerenes with molecular oxygen  

SciTech Connect

The molecular fullerenes were investigated in their reactivity towards molecular oxygen in the form of thin films on silicon and as powders. Several techniques including x-ray diffraction, EPR, photoabsorption, TPD and thermal analysis were utilized.

Wohlers, M.; Werner, H.; Bauer, A.; Belz, T. [Institut der Max Planck Gesellschaft, Berlin (Germany)] [and others

1996-10-01

294

Synthesis of highly quenching fullerene derivatives for biosensor applications  

E-print Network

This dissertation examines the synthesis of fullerene-based fluorescence quenchers for numerous biosensor applications. The Introduction describes the need for biosensors in our society, what they are and various biosensing ...

Pérez, Vanessa Virginia, 1981-

2004-01-01

295

Production and Consumption of Reactive Oxygen Species by Fullerenes  

EPA Science Inventory

Reactive oxygen species (ROS) are one of the most important intermediates in chemical, photochemical, and biological processes. To understand the environmental exposure and toxicity of fullerenes better, the production and consumption of ROS (singlet oxygen, superoxide, hydrogen ...

296

Diffuse interstellar bands in fullerene planetary nebulae: the fullerenes - diffuse interstellar bands connection  

E-print Network

We present high-resolution (R~15000) VLT/UVES optical spectra of two planetary nebulae (PNe; Tc 1 and M 1-20) where C60 (and C70) fullerenes have already been found. These spectra are of high-quality (S/N > 300) for PN Tc 1, which permits us to search for the expected electronic transitions of neutral C60 and diffuse interstellar bands (DIBs). Surprisingly, we report the non-detection of the most intense optical bands of C60 in Tc 1, although this could be explained by the low C60 column density estimated from the C60 infrared bands if the C60 emission peaks far away from the central star. The strongest and most common DIBs in both fullerene PNe are normal for their reddening. Interestingly, the very broad 4428 A DIB and the weaker 6309 A DIB are found to be unusually intense in Tc 1. We also report the detection of a new broad (FWHM~5 A) unidentified band at ~6525 A. We propose that the 4428 A DIB (probably also the 6309 A DIB and the new 6525 A band) may be related to the presence of larger fullerenes (e.g....

Garcia-Hernandez, D A

2013-01-01

297

Fast atom bombardment and high performance tandem mass spectrometry of platinum(II) oligodeoxyribonucleotide fragments  

NASA Astrophysics Data System (ADS)

The antitumor drug cisplatin [cis-diamminedichloroplatinum(II),cis-DDP] exerts its biological activity by binding to cellular DNA. In order to evaluate the utility of mass spectrometry as a possible new approach to investigate the number and type of Pt-DNA adducts in both mechanistic and clinical studies, a systematic survey of the fast atom bombardment (FAB) and high performance tandem mass spectrometry (MS---MS) spectra of a series of well-defined adducts has been carried out. Included in the set of compounds were adducts between cisplatin or its trans isomer and oligodeoxyribonucleotides containing two to six bases, selected to represent all the known binding modes of cisplatin to DNA, and stable isotope-labeled (15N, 195Pt) complexes. In both positive- and negative-ion FAB mass spectra, all compounds yield ions corresponding to the singly-charged intact cluster, and to fragments that arise by loss of one or two ammine groups. The isotope ratio patterns of the clusters indicate that mixed species containing varying numbers of hydrogens are present. MS--MS spectra obtained after high energy (1-7keV) collisionally-induced dissociation (CID) have more extensive fragmentation. Two sets of product ions indicative of the Pt- binding site are consistently present; these correspond to Pt(NH3)0-2 (Bx or y) and Pt(NH3)0-2 (Bx By), where Bx and By are the nucleobasis linked to Pt in the adduct. CID mass spectra recorded at 1 keV have additional product ions related to the nucleotide sequence.

Costello, Catherine E.; Comess, Kenneth M.; Plaziak, Adam S.; Bancroft, Daniel P.; Lippard, Stephen J.

1992-12-01

298

Modification of molecular transitions in fullerene films under ion impacts  

SciTech Connect

The photoluminescence properties of as-deposited and 90 MeV Si ion irradiated fullerene films are reported. The irradiation of fullerene films leads to some enhancement or quenching in molecular transition intensities (photoluminescence intensities) depending on the ion fluence. These effects are explained in terms of lowering in the energy level symmetry resulting from induced chemical disordering. The structural modifications occurring upon irradiation were investigated using Fourier transform infrared and UV-vis spectroscopies.

Kumar, Amit [Institut Neel, Centre National de la Recherche Scientifique (CNRS) and Universite Joseph Fourier (UJF), 25 rue des Martyrs, BP166, 38042 Grenoble Cedex 9 (France); Podhorodecki, A.; Misiewicz, J. [Institute of Physics, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw (Poland); Avasthi, D. K. [Material Science Group, Inter-University Accelerator Centre, Aruna Asaf Ali Marg, PB-10502, New Delhi 110067 (India); Pivin, J. C. [Centre Spectrometrie Nucleaire et de Spectrometrie de Masse (CSNSM), IN2P3-CNRS, Batiment 108, Orsay Campus 91405 (France)

2009-01-15

299

Fullerene derivatives: an attractive tool for biological applications  

Microsoft Academic Search

The fullerene family, and especially C60, has very appealing photo-, electro-chemical and physical properties, which can be exploited in many and different biological fields. Fullerene is able to fit inside the hydrophobic cavity of HIV proteases, inhibiting the access of substrates to the catalytic site of the enzyme. It can be used as radical scavenger; in fact some water-soluble derivatives

Susanna Bosi; Tatiana Da Ros; Giampiero Spalluto; Maurizio Prato

2003-01-01

300

Morphology of polymer\\/fullerene bulk heterojunction solar cells  

Microsoft Academic Search

Within the different organic photovoltaic devices the conjugated polymer\\/fullerene bulk heterojunction approach is one of the foci of today's research interest. These devices are highly dependent on the solid state nanoscale morphology of the two components (donor\\/acceptor) in the photoactive layer. The need for finely phase separated polymer-fullerene blends is expressed by the limited exciton diffusion length present in organic

Harald Hoppe; Niyazi Serdar Sariciftci

2006-01-01

301

Photo-induced and thermal processes in fullerene solutions  

NASA Astrophysics Data System (ADS)

The experimental investigations of photo-induced quenching of singlet oxygen luminescence in fullerene solutions (C 60 and C 70 in CCI 4) at optical pumping have shown presence of dependence of 1g?g 0 II lifetime in a solution on initial fullerene concentration, optical pumping intensity and temperature of the solution. The increase of any of these three factors results in the reduction of the singlet oxygen lifetime in the solution, and for C 70 these effects are much stronger than for C 60. It is shown that at pulse optical excitation the solution C 60 is stable and restores the properties some time after the influence. These effects can not be explained by only thermal mechanism, the major part is played by process of formation of fullerene-oxygen complexes which as a quencher for the state 1?g 0 II. These complexes are unstable and are decomposed later into initial components. The initial fullerene C 60 concentration is completely restored in the solution. The initial fullerene C 70 concentration is partly restored in the solution. All these conclusions are based on the results of the study of absorption spectra of fullerene solutions before and some time after the influence on solutions of pulse optical excitation. For CW irradiation, the effects of photoinduced quenching of singlet oxygen luminescence in fullerene solutions have been studied as well. These phenomena are to be considered when developing a generators of singlet oxygen for fullerene-oxygen-iodine laser. The temperature of solution also plays an important role in the development of singlet oxygen generators. To increase the generator efficiency it is necessary to cool the solution efficiently.

Bagrov, I. V.; Belousova, I. M.; Danilov, O. B.; Kiselev, V. M.; Murav'eva, T. D.; Sosnov, E. N.

2007-04-01

302

Patterning polymer-fullerene nanocomposite thin films with light.  

PubMed

The stability and association of polymer-fullerene films upon thermal annealing depends strongly on exposure to light, even at ambient conditions. As a result, dewetting of nanocomposite films can be prevented and the characteristic lengthscales of phase separated morphologies finely tuned. Coupling photopatterning with either self-organization process provides a powerful route for the directed assembly of fullerene-based nanocomposites into functional "circuits". PMID:23139170

Wong, Him Cheng; Higgins, Anthony M; Wildes, Andrew R; Douglas, Jack F; Cabral, João T

2013-02-20

303

Structure and Thermophysical Properties of Fullerene C60 Aqueous Solutions  

Microsoft Academic Search

The structure and thermophysical properties of fullerene C60aqueous solutions were investigated both experimentally and theoretically. The aggregation kinetics results indicated that the structure of fullerene C60aggregates in water could be described as a fractal system. The IR and electronic absorption spectra obtained confirm the presence of the crystalline phase in aqueous solution. The numerical values of thermodynamic coefficientsaP,ßT,ßS,cP, andcV, and

Yu. I. Prylutskyy; S. S. Durov; L. A. Bulavin; I. I. Adamenko; K. O. Moroz; I. I. Geru; I. N. Dihor; P. Scharff; P. C. Eklund; L. Grigorian

2001-01-01

304

Models of cluster formation in solutions of fullerenes  

Microsoft Academic Search

A review of experimental and theoretical studies of the formation and growth of clusters in solutions of fullerenes is given.\\u000a General problems of fullerene cluster formation in solutions are considered. The main directions and goals of studies are\\u000a specified. The experimental data on solutions with various polarities obtained by various methods, including visible and UV\\u000a spectroscopy, dynamic light scattering, small-angle

M. V. Avdeev; V. L. Aksenov; T. V. Tropin

2010-01-01

305

Model-independent test of the truncated crater function theory of surface morphology evolution during ion bombardment  

NASA Astrophysics Data System (ADS)

A broad class of "local response" theories seeks to predict morphology evolution during energetic particle irradiation in terms of average surface height response to individual impacts—an approach that has been generalized by the crater function formalism of Norris et al. [J. Phys.: Condens. Matter 21, 224017 (2009), 10.1088/0953-8984/21/22/224017; Nat. Commun. 2, 276 (2011), 10.1038/ncomms1280]. Keeping only the terms in the crater function formalism associated with the response of a flat surface has facilitated the use of molecular dynamics simulations of individual ion impacts to predict the stability or instability of a flat surface to ion bombardment. Here we report a sensitive experimental test of this truncated crater function theory that is independent of any a priori knowledge of the crater function itself. Existing measurements for 1 keV Ar+/Si and Kr+/Ge are inconsistent with the predictions of truncated crater function theory, for any conceivable crater function, at high bombardment angles. The failure of the theory suggests that the prediction of surface evolution from simulations of single-ion impacts will be more challenging than had been assumed.

Perkinson, Joy C.; Anzenberg, Eitan; Aziz, Michael J.; Ludwig, Karl F.

2014-03-01

306

Diffuse interstellar bands in (proto-) fullerene-rich environments  

E-print Network

The recent infrared detection of fullerenes (C60 and C70) in Planetary Nebulae (PNe) and R Coronae Borealis (RCB) stars offers a beautiful opportunity for studying the diffuse interstellar bands (DIBs) in sources where fullerenes are abundant. Here we present for the first time a detailed inspection of the optical spectra of the hot RCB star DY Cen and two fullerene PNe (Tc 1 and M 1-20), which permits us to directly explore the fullerenes - DIB connection. The DIB spectrum of DY Cen (Garcia-Hernandez et al. 2012a) is remarkably different from that in fullerene PNe (Garcia-Hernandez & Diaz-Luis 2013). In particular, Tc 1 displays unusually strong 4428 A and 6309 A DIBs, which are normal (or not seen) in DY Cen. On the other hand, DY Cen displays an unusually strong 6284 A DIB that is found to be normal in fullerene PNe. We also report the detection of new broad and unidentified features centered at 4000 A and 6525 A in DY Cen and Tc 1, respectively. We suggest that the new 4000 A band seen in DY Cen may b...

Garcia-Hernandez, D A

2013-01-01

307

Fullerene derivatives protect endothelial cells against NO-induced damage  

NASA Astrophysics Data System (ADS)

Functional fullerene derivatives have been demonstrated with potent antioxidation properties. Nitric oxide (NO) is a free radical that plays a part in leading to brain damage when it is accumulated to a high concentration. The possible scavenging activity of NO by the hydroxylated fullerene derivative C60(OH)22 and malonic acid derivative C60(C(COOH)2)2 was investigated using primary rat brain cerebral microvessel endothelial cells (CMECs). Results demonstrate that sodium nitroprusside (SNP), used as an NO donor, caused a marked decrease in cell viability and an increase in apoptosis. However, fullerene derivatives can remarkably protect against the apoptosis induced by NO assault. In addition, fullerene derivatives can also prevent NO-induced depolymerization of cytoskeleton and damage of the nucleus and accelerate endothelial cell repair. Further investigation shows that the sudden increase of the intercellular reactive oxygen species (ROS) induced by NO was significantly attenuated by post-treatment with fullerene derivatives. Our results suggest that functional fullerene derivatives are potential applications for NO-related disorders.

Lao, Fang; Li, Wei; Han, Dong; Qu, Ying; Liu, Ying; Zhao, Yuliang; Chen, Chunying

2009-06-01

308

Binding of fullerenes to amyloid beta fibrils: size matters.  

PubMed

Binding affinity of fullerenes C20, C36, C60, C70 and C84 for amyloid beta fibrils is studied by docking and all-atom molecular dynamics simulations with the Amber force field and water model TIP3P. Using the molecular mechanic-Poisson Boltzmann surface area method one can demonstrate that the binding free energy linearly decreases with the number of carbon atoms of fullerene, i.e. the larger is the fullerene size, the higher is the binding affinity. Overall, fullerenes bind to A?9-40 fibrils stronger than to A?17-42. The number of water molecules trapped in the interior of 12A?9-40 fibrils was found to be lower than inside pentamer 5A?17-42. C60 destroys A?17-42 fibril structure to a greater extent compared to other fullerenes. Our study revealed that the van der Waals interaction dominates over the electrostatic interaction and non-polar residues of amyloid beta peptides play the significant role in interaction with fullerenes providing novel insight into the development of drug candidates against Alzheimer's disease. PMID:25123396

Huy, Pham Dinh Quoc; Li, Mai Suan

2014-10-01

309

Photodynamic therapy with fullerenes in vivo: reality or a dream?  

PubMed

Photodynamic therapy (PDT) employs the combination of nontoxic photosensitizers and visible light that is absorbed by the chromophore to produce long-lived triplet states that can carry out photochemistry in the presence of oxygen to kill cells. The closed carbon-cage structure found in fullerenes can act as a photosensitizer, especially when functionalized to impart water solubility. Although there are reports of the use of fullerenes to carry out light-mediated destruction of viruses, microorganisms and cancer cells in vitro, the use of fullerenes to mediate PDT of diseases such as cancer and infections in animal models is less well developed. It has recently been shown that fullerene PDT can be used to save the life of mice with wounds infected with pathogenic Gram-negative bacteria. Fullerene PDT has also been used to treat mouse models of various cancers including disseminated metastatic cancer in the peritoneal cavity. In vivo PDT with fullerenes represents a new application in nanomedicine. PMID:22122587

Sharma, Sulbha K; Chiang, Long Y; Hamblin, Michael R

2011-12-01

310

Photodynamic therapy with fullerenes in vivo: reality or a dream?  

PubMed Central

Photodynamic therapy (PDT) employs the combination of nontoxic photosensitizers and visible light that is absorbed by the chromophore to produce long-lived triplet states that can carry out photochemistry in the presence of oxygen to kill cells. The closed carbon-cage structure found in fullerenes can act as a photosensitizer, especially when functionalized to impart water solubility. Although there are reports of the use of fullerenes to carry out light-mediated destruction of viruses, microorganisms and cancer cells in vitro, the use of fullerenes to mediate PDT of diseases such as cancer and infections in animal models is less well developed. It has recently been shown that fullerene PDT can be used to save the life of mice with wounds infected with pathogenic Gram-negative bacteria. Fullerene PDT has also been used to treat mouse models of various cancers including disseminated metastatic cancer in the peritoneal cavity. In vivo PDT with fullerenes represents a new application in nanomedicine. PMID:22122587

Sharma, Sulbha K; Chiang, Long Y; Hamblin, Michael R

2012-01-01

311

Intravenous coronary angiography utilizing K-emission and bremsstrahlung X-rays produced by electron bombardment  

SciTech Connect

The screening of the general population for coronary artery disease would be practical if a method existed for visualizing the extent of occlusion after an intravenous injection of contrast agent. Measurements performed with synchrotron radiation at SSRL and NSLS have shown that such an intravenous angiography procedure would be possible with an intense source of monochromatic X-rays. Because of the high cost of an electron synchrotron, theoretical analysis and experiments using inanimate phantoms has been undertaken to demonstrate the feasibility of using the spectrum produced by two appropriately chosen anode materials when bombarded with electrons in the 100--500 keV energy range for angiography. By using the X-rays emitted at 120{degree} to the incident electron direction, about 20--30% of the X-ray intensity would be due to K-emission lines. Calculations using the TIGERP Monte Carlo Code, have shown that high quality angiograms of human coronary arteries should be possible with a contrast agent containing ytterbium, if an electron beam pulses of 16 kJ were used for each anode target. The experimental program supported in part by the DOE has consisted of these theoretical calculations and experiments at the Dynamitron Electron Accelerator Facility at BNL.

NONE

1992-12-31

312

Scintillation degradation of YAG: Ce under low-energy ion bombardment  

NASA Astrophysics Data System (ADS)

We have measured the degradation of the scintillation yield of single crystal YAG: Ce under He+?irradiation at low energies between 28 and 58 keV. The scintillator was irradiated at the rare isotope ReAccelerator (ReA) facility at the National Superconducting Cyclotron Laboratory (NSCL). The scintillation emission is attributed to its rapid 5d-4f transition of Ce3+ ions. As the bombardment time increases, an exponential decay of the light output is observed due to the induced radiation damage of the crystal lattice. Color centers formed by the radiation damage are likely to act as exciton capturing centers, leading to a quench of the scintillator yield. It is possible that these color centers are oxygen vacancies with trapped electrons or the formation of Ce4+ and Y2+. The decrease of the experimentally observed light yield as a function of particle fluence is found to be in fair agreement with the Birks model. Analysis indicates that the damage cross section of scintillation centers slightly decreases with the ion energy. The value of the relative exciton capture probability for YAG: Ce is considerably small compared to the magnitude proposed by Birks for anthracene under ?-particle irradiation. On the other hand, the half brightness fluence is estimated to be larger at higher energy because the ion particles create less damaged centers per unit of path length and activate more luminescence centers. Therefore, the scintillator degrades slower and exhibits better scintillation efficiency under higher-energy irradiation.

Lin, L. Y.; Benatti, C.; Perdikakis, G.; Leitner, D.; Krause, S. W.; Yurkon, J.

2013-01-01

313

Towards a fullerene-based quantum computer  

E-print Network

Molecular structures appear to be natural candidates for a quantum technology: individual atoms can support quantum superpositions for long periods, and such atoms can in principle be embedded in a permanent molecular scaffolding to form an array. This would be true nanotechnology, with dimensions of order of a nanometre. However, the challenges of realising such a vision are immense. One must identify a suitable elementary unit and demonstrate its merits for qubit storage and manipulation, including input / output. These units must then be formed into large arrays corresponding to an functional quantum architecture, including a mechanism for gate operations. Here we report our efforts, both experimental and theoretical, to create such a technology based on endohedral fullerenes or 'buckyballs'. We describe our successes with respect to these criteria, along with the obstacles we are currently facing and the questions that remain to be addressed.

Simon C Benjamin; Arzhang Ardavan; G Andrew D Briggs; David A Britz; Daniel Gunlycke; John Jefferson; Mark A G Jones; David F Leigh; Brendon W Lovett; Andrei N Khlobystov; S A Lyon; John J L Morton; Kyriakos Porfyrakis; Mark R Sambrook; Alexei M Tyryshkin

2005-11-21

314

Dispersion interaction stabilizes sterically hindered double fullerenes.  

PubMed

By state-of-the-art quantum chemical methods, we show that for bulky functional groups like cyclohexane, [20]fullerene, dodecahedrane, and C60 , the attractive dispersion interaction can have a greater impact on stereochemistry than the repulsive steric effect, making the compact isomer the more stable one. In particular, for the double C60 adduct of pentacene 1, the syn isomer should be the main product instead of the anti one inferred in the original synthesis experiment (Y. Murata et?al., J. Org. Chem.- 1999, 64, 3483). With and without dispersion interactions taken into account, the Gibbs energy difference ?G(syn-anti) is -6.36 and +1.15?kcal?mol(-1) , respectively. This study reminds us that dispersion interactions as well as electrostatic or hyperconjugation effects, etc. can lead to some unusual stereochemical phenomena. PMID:25165020

Zhang, Jun; Dolg, Michael

2014-10-20

315

Fullerene Embedded Shape Memory Nanolens Array  

NASA Astrophysics Data System (ADS)

Securing fragile nanostructures against external impact is indispensable for offering sufficiently long lifetime in service to nanoengineering products, especially when coming in contact with other substances. Indeed, this problem still remains a challenging task, which may be resolved with the help of smart materials such as shape memory and self-healing materials. Here, we demonstrate a shape memory nanostructure that can recover its shape by absorbing electromagnetic energy. Fullerenes were embedded into the fabricated nanolens array. Beside the energy absorption, such addition enables a remarkable enhancement in mechanical properties of shape memory polymer. The shape memory nanolens was numerically modeled to impart more in-depth understanding on the physics regarding shape recovery behavior of the fabricated nanolens. We anticipate that our strategy of combining the shape memory property with the microwave irradiation feature can provide a new pathway for nanostructured systems able to ensure a long-term durability.

Jeon, Sohee; Jang, Jun Young; Youn, Jae Ryoun; Jeong, Jun-Ho; Brenner, Howard; Song, Young Seok

2013-11-01

316

Fullerene Embedded Shape Memory Nanolens Array  

PubMed Central

Securing fragile nanostructures against external impact is indispensable for offering sufficiently long lifetime in service to nanoengineering products, especially when coming in contact with other substances. Indeed, this problem still remains a challenging task, which may be resolved with the help of smart materials such as shape memory and self-healing materials. Here, we demonstrate a shape memory nanostructure that can recover its shape by absorbing electromagnetic energy. Fullerenes were embedded into the fabricated nanolens array. Beside the energy absorption, such addition enables a remarkable enhancement in mechanical properties of shape memory polymer. The shape memory nanolens was numerically modeled to impart more in-depth understanding on the physics regarding shape recovery behavior of the fabricated nanolens. We anticipate that our strategy of combining the shape memory property with the microwave irradiation feature can provide a new pathway for nanostructured systems able to ensure a long-term durability. PMID:24253423

Jeon, Sohee; Jang, Jun Young; Youn, Jae Ryoun; Jeong, Jun-ho; Brenner, Howard; Song, Young Seok

2013-01-01

317

Static dipole polarizability of C70 fullerene  

E-print Network

The electronic and vibrational contributions to the static dipole polarizability of C70 fullerene are determined using the finite-field method within the density functional formalism. Large polarized Gaussian basis sets augmented with diffuse functions are used and the exchange-correlation effects are described within the Perdew-Burke-Ernzerhof generalized gradient approximation (PBE-GGA). The calculated polarizability of C70 is 103 Angstrom^3, in excellent agreement with the experimental value of 102 Angstrom^3, and is completely determined by the electronic part, vibrational contribution being negligible. The ratio of polarizabilities of C70 and C60 is 1.26. The comparison of polarizability calculated with only local terms (LDA) in the PBE functional to that obtained with PBE-GGA shows that LDA is sufficient to determine the static dipole polarizability of C70.

Zope, Rajendra R

2007-01-01

318

Permittivity of low-concentration C60 fullerene solutions in p-xylene  

NASA Astrophysics Data System (ADS)

The frequency dependence of the permittivity of C60 fullerene solutions in p-xylene has been determined at various small concentrations of fullerene molecules. The results are discussed using notions of the solution structure.

Ginzburg, B. M.; Tuichiev, Sh.; Shukhiev, S.

2009-06-01

319

Changes in Agglomeration of Fullerenes During Ingestion and Excretion in Thamnocephalus Platuyrus  

EPA Science Inventory

The crustacean Thamnocephalus platyurus was exposed to aqueous suspensions of fullerenes C60 and C70. Aqueous fullerene suspensions were formed by stirring C60 and C70 as received from a commercial vendor in deionized water (term...

320

Size-exclusive Nanosensor for Quantitative Analysis of Fullerene C60: A Concept Paper  

EPA Science Inventory

This paper presents the first development of a mass-sensitive nanosensor for the isolation and quantitative analyses of engineered fullerene (C60) nanoparticles, while excluding mixtures of structurally similar fullerenes. Amino-modified beta cyclodextrin (ß-CD-NH...

321

Field-induced transition from room-temperature ferromagnetism to diamagnetism in proton-irradiated fullerene.  

PubMed

Room-temperature ferromagnetism in proton-irradiated C60 fullerene is demonstrated. The ferromagnetism turns into diamagnetism intrinsic to the fullerene as the magnetic field increases above a critical field. PMID:23946203

Lee, Kyu Won; Kweon, Hyocheon; Lee, Cheol Eui

2013-10-18

322

Characteristics of ultra-low-energy Cs + ion beam bombardments  

NASA Astrophysics Data System (ADS)

Shallow arsenic implants and extra-thin film (SiON) are routinely analyzed by modern SIMS under ultra-low-energy Cs + ion beam bombardment, either at oblique (<60°) or glancing (˜80°) incident angle [J. Surf. Anal. 6 (3) (1999) A-3; in: A. Benninghoven, et al. (Eds.), Proceedings of the SIMS XII, Elsevier, Amsterdam, 1999, p. 549]. This article investigates the basic aspects of ultra-low-energy Cs + ion beam bombardment using a delta-doped boron sample (four layers, 5.3 nm per cycle), such as useful yield, depth resolution and changes in sputter rate in the near surface region. Our results indicated that there is a magic incidence angle (˜70°) at which the depth resolution is very poor, and at glancing (˜80°) incident angle the best depth resolution is observed.

Li, Zhanping; Hoshi, Takahiro; Oiwa, Retsu

2003-01-01

323

Factors affecting gene delivery by particle bombardment of Dendrobium orchids  

Microsoft Academic Search

Summary  Five parameters were examined for their effect on transformation ofDendrobium tissues by microprojectile bombardment. The superpromoter in pBI426 produced at least 1.5 times as many transient transformants\\u000a as the single cauliflower mosaic virus 35S promoter in pBI121 (37 to 69% vs. 0 to 44%) with dark and frequent GUS (?-glucuronidase) staining. Tissue, genotype, and type of microparticle significantly affected transient

Guo-Ling Nan; Adelheid R. Kuehnle

1995-01-01

324

Genetic transformation of sweet potato by particle bombardment  

Microsoft Academic Search

Transient and stable expression of foreign genes has been achieved in sweet potato using the particle bombardment system of gene delivery. Callus and root isolates of two genotypes (Jewel and TIS-70357) with positive signs of transformation have been recovered. Tungsten microcarriers coated with plasmid DNA (pBI 221 containing the gusA gene) were accelerated at high velocity using a biolistic device

C. S. Prakash; U. Varadarajan

1992-01-01

325

Bombardment as a cause of the lunar asymmetry.  

NASA Technical Reports Server (NTRS)

The moon is asymmetric in crustal thickness and also in the distribution of maria and gamma radioactivity. Early bombardment of the moon by planetesimals, in both heliocentric and geocentric orbits, is examined as a possible cause of the asymmetries. The presence of a massive companion (earth) causes a spin-orbit coupled moon to be bombarded nonuniformly. The most pronounced local concentration of impacts would have occurred on the west limb of the moon, when it orbited close to the earth, if low-eccentricity heliocentric planetesimals were still abundant in the solar system at that time. A very intense bombardment of this type could have redistributed crustal material on the moon, thinning the west limb crust appreciably. This would have caused a change in position of the principal axes of inertia, and a reorientation of the spin-orbit coupled moon such that the thinnest portion of its crust turned toward one of the poles. Erupting lavas would have preferentially flooded such a thin-crusted, low-lying area. This would have caused another readjustment of principal moments, and a reorientation of the moon such that the mare areas tipped toward the equator.

Wood, J. A.

1973-01-01

326

Real Time Microscopy, Kinetics, and Mechanism of Giant Fullerene Evaporation J. Y. Huang*  

E-print Network

Real Time Microscopy, Kinetics, and Mechanism of Giant Fullerene Evaporation J. Y. Huang* Center microscopy observing the shrinkage of single- layer giant fullerenes (GF). At temperatures 2000 C, the GF volume reduces by greater than one 100-fold while the fullerene shell remains intact, evolving from

Powles, Rebecca

327

A Molecular Dynamics Simulation for the Formation Mechanism of Fullerene Shigeo Maruyama and Yasutaka Yamaguchi  

E-print Network

A Molecular Dynamics Simulation for the Formation Mechanism of Fullerene Shigeo Maruyama and Yasutaka Yamaguchi Abstract The formation mechanism of fullerene, the new type of carbon molecule to investigate the formation mechanism of fullerene, the clustering process starting from isolated carbon atoms

Maruyama, Shigeo

328

Submitted to Phys. Rev. B, June 2013 Ultralow thermal conductivity of fullerene derivatives  

E-print Network

1 Submitted to Phys. Rev. B, June 2013 Ultralow thermal conductivity of fullerene derivatives. reported that the fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) has the lowest an estimate of the thermally excited modes per molecule. Key words: Organic semiconductor, Fullerene, Ultralow

Cahill, David G.

329

Nano Res (2010) 3: 929792 Enhanced Interactions Between a C60 Fullerene and a  

E-print Network

Nano Res (2010) 3: 92�9792 Enhanced � Interactions Between a C60 Fullerene and a Buckle Bend of a bent double-walled carbon nanotube is presented. The fullerene interaction is non-covalent, suggesting confirm that the increased interaction area associated with a buckle is sufficient to trap a fullerene

Cuniberti, Gianaurelio

330

Free Carrier Generation in Fullerene Acceptors and Its Effect on Polymer Photovoltaics  

E-print Network

Free Carrier Generation in Fullerene Acceptors and Its Effect on Polymer Photovoltaics George F is this also true for many of the soluble fullerene derivatives commonly used in organic photovoltaics of free carrier generation in fullerenes can have a significant impact on the interpretation of data

McGehee, Michael

331

Fullerene doped glasses Fucheng Lin, Sen Mao, Zhicong Meng, and Heping Zeng  

E-print Network

Fullerene doped glasses Fucheng Lin, Sen Mao, Zhicong Meng, and Heping Zeng Shanghai Institute 1994; accepted for publication 15 September 1994 Optical glasses doped with a fullerene mixture of C60/C70 were made in our lab. Three peaks, corresponding to C60, C70, and a modified fullerene possibly

Guo, Ting

332

Charge Transfer and Chemisorption of Fullerene Molecules on Metal Surfaces: Application to Dynamics of Nanocars  

E-print Network

Charge Transfer and Chemisorption of Fullerene Molecules on Metal Surfaces: Application to Dynamics Information ABSTRACT: It is widely believed that the dynamics of surface-bound fullerene molecules theoretical approach to describe charge transfer and chemisorption processes for fullerenes on gold surfaces

333

LASER ABLATION SYNTHESIS OF ZINC OXIDE CLUSTERS: A NEW FAMILY OF FULLERENES?  

E-print Network

1 LASER ABLATION SYNTHESIS OF ZINC OXIDE CLUSTERS: A NEW FAMILY OF FULLERENES? Alexander V to fullerenes. A local abundance minimum at n = 13 provides an additional evidence for the presence in the ablation plume of fullerene-like (ZnO)n clusters. #12;2 Recently much interest has been shown in Zn

Paris-Sud XI, Université de

334

A semi-empirical molecular orbital study of freestanding and fullerene-encapsulated Mo nanoclusters  

E-print Network

A semi-empirical molecular orbital study of freestanding and fullerene-encapsulated Mo nanoclusters as implemented in the VAMP module of Materials Studiow , of both freestanding and fullerene by opening of hexagon­hexagon (6­6) carbon bonds that lead eventually to a splitting open of the fullerene

Elliott, James

335

10694 J. Phys. Chem. 1995,99, 10694-10697 Self-Assembly of Tubular Fullerenes  

E-print Network

10694 J. Phys. Chem. 1995,99, 10694-10697 Self-Assembly of Tubular Fullerenes Ting Guo,?Pave1 of multiwalled fullerenes are shown here to self-assemble under homogeneous gas-phase conditions of carbon for the annealing and growth of C a and other spheroidal shells. Tubular fullerenes are known to be less stable than

Guo, Ting

336

Comparison of protons, carbon and fullerene impacts on a carbon cylinder  

E-print Network

Comparison of protons, carbon and fullerene impacts on a carbon cylinder R.P. Webb *, I.H. Wilson between the impacts of protons, carbon atoms and fullerene molecules on an elongated strong of carbon; 887.15.K; 36.40 Keywords: Ion beams; Molecular dynamics simulation; Carbon; DNA; Fullerene 1

Webb, Roger P.

337

Calculated energy loss of swift fullerene ion beam in InP Isabel Abril1  

E-print Network

Calculated energy loss of swift fullerene ion beam in InP Isabel Abril1 , Rafael Garcia-Molina2 of semiconductors with fullerene has been used to induce the formation of tracks. It is now accepted that target to calculate the track diameter. In the case of cluster beams, like fullerenes, the electronic excitation

Paris-Sud XI, Université de

338

Experimental evidence for the interaction of C-60 fullerene with lipid vesicle membranes  

E-print Network

Experimental evidence for the interaction of C-60 fullerene with lipid vesicle membranes Jernej of experimental evidence of the effects of C-60 fullerene on lipid bilayers. The aim of this study is to assess steps which increase the probability for fullerenes to insert into the MLVs. Our experimental findings

Iglic, Ales

339

Hydrogen Molecules inside Fullerene C70: Quantum Dynamics, Energetics, Maximum Occupancy, And Comparison with C60  

E-print Network

Hydrogen Molecules inside Fullerene C70: Quantum Dynamics, Energetics, Maximum Occupancy for reliable theoretical predictions regarding the stability of the endohedral fullerene complexes fullerenes, which has not been attempted prior to the present work. Endohedral complexes of C60 and C70

Turro, Nicholas J.

340

Ni-dispersed fullerenes: Hydrogen storage and desorption properties Weon Ho Shin and Seong Ho Yang  

E-print Network

Ni-dispersed fullerenes: Hydrogen storage and desorption properties Weon Ho Shin and Seong Ho Yang; published online 31 January 2006 Our study shows that the H2 storage media using Ni-dispersed fullerenes on the fullerene surface can store up to three H2 molecules. Consequently, at high Ni coverage, Ni

Goddard III, William A.

341

International Journal of Mass Spectrometry 252 (2006) 7995 The frequency factor in statistical fullerene decay  

E-print Network

fullerene decay K. Hansena,, E.E.B. Campbella, O. Echtb a Department of Physics, G¨oteborg University, SE online 24 March 2006 Abstract Experiments on fullerene decay are reviewed and the frequency factor for C2 , in good agreement with experimental results. © 2006 Elsevier B.V. All rights reserved. Keywords: Fullerene

Hansen, Klavs

342

Chemical reaction of metal-fullerene in gas phase (2) >Masamichi Konoa  

E-print Network

f18-068 Chemical reaction of metal-fullerene in gas phase (2) ·>Masamichi Konoa , Syuhei Inoueb.of Tokyo Since the discovery of macroscopic generation and purification procedure of fullerenes and endohedral fullerenes, the geometric structure and the formation mechanism of them has been one of the most

Maruyama, Shigeo

343

Electron and Hole Contributions to the Terahertz Photoconductivity of a Conjugated Polymer:Fullerene Blend Identified  

E-print Network

Electron and Hole Contributions to the Terahertz Photoconductivity of a Conjugated Polymer:Fullerene, negative charges are transferred to fullerenes, while positive polarons remain on polymers/monomers. Vastly/ fullerene bulk heterojunction systems,2 comprehensive study focusing on the charge transport on the earliest

KuÂ?el, Petr

344

ON THE NUMERICAL SIMULATION OF FULLERENE NANOTUBES: C 100:000:000 AND BEYOND !  

E-print Network

ON THE NUMERICAL SIMULATION OF FULLERENE NANOTUBES: C 100:000:000 AND BEYOND ! ATTILA CAGLAR properties of fullerenes and especially nanotubes in experiments is very difficult. Here, computer of our numerical experiments. We considered the reactive collision of C 60 fullerenes with benzyne and

Sminchisescu, Cristian

345

Creation of a gradient polymer-fullerene interface in photovoltaic devices by thermally controlled interdiffusion  

E-print Network

Creation of a gradient polymer-fullerene interface in photovoltaic devices by thermally controlled 24062-1704 Received 29 July 2002; accepted 27 September 2002 Efficient polymer-fullerene photovoltaic the semiconducting polymer to the fullerene acceptor. We describe studies in which a bilayer system consisting

Heflin, Randy

346

Ultrafast conductivity in a low-band-gap polyphenylene and fullerene blend studied by terahertz spectroscopy  

E-print Network

Ultrafast conductivity in a low-band-gap polyphenylene and fullerene blend studied by terahertz-band-gap polyphenylene copolymer and fullerene derivative. The optical excitation pulse generates free holes delocalized in these systems. The pri- mary excitation in polymer/fullerene bulk heterojunctions is an exciton on the polymer

KuÂ?el, Petr

347

Quantum rotation of ortho and para-water encapsulated in a fullerene cage  

E-print Network

Quantum rotation of ortho and para-water encapsulated in a fullerene cage Carlo Beduza , Marina and ortho­para conversion of single water molecules trapped inside closed fullerene cages. The existence surgery" (1­3) involves opening an orifice in fullerene (C60) cages by a series of chemical reactions

Turro, Nicholas J.

348

FT-ICR studies of metal-carbon binary clusters for formation mechanism of endohedral fullerene  

E-print Network

FT-ICR studies of metal-carbon binary clusters for formation mechanism of endohedral fullerene the clustering process of endohedral metallo-fullerene (Figure 1). Cluster beams were generated by laser-vaporizations of various sample materials used for arc-discharge generation of metal- containing fullerene and SWNT (single

Maruyama, Shigeo

349

TEMPERATURE-DEPENDENT RAMAN SPECTROSCOPY OF FULLERENE AND CARBORANE NANOCAR WHEELS  

E-print Network

TEMPERATURE-DEPENDENT RAMAN SPECTROSCOPY OF FULLERENE AND CARBORANE NANOCAR WHEELS B. Shih1,2 , C investigate the effects of temperature between 10o C and 70o C on fullerene and carborane nanocar wheels-Dependent Raman Spectroscopy of Fullerene Nanocar Wheels Acknowledgement This material is based upon work

Mellor-Crummey, John

350

Two-qubit gates between noninteracting qubits in endohedral-fullerene-based quantum computation  

E-print Network

Two-qubit gates between noninteracting qubits in endohedral-fullerene-based quantum computation fullerenes 15 N@C60 or 31 P@C60, within today's magnetic resonance techniques. Since there is no interaction a universal set of quantum gates in fullerene-based quantum computation. DOI: 10.1103/PhysRevA.75.012318 PACS

Suter, Dieter

351

Parametrization and Application of a Coarse Grained Force Field for Benzene/Fullerene Interactions with Lipids  

E-print Network

Parametrization and Application of a Coarse Grained Force Field for Benzene/Fullerene Interactions Recently, we reported new coarse grain (CG) force fields for lipids and phenyl/fullerene based molecules. In the C60 lipid systems, the fullerenes were shown to aggregate even at the lowest concentrations

Nielsen, Steven O.

352

MOLECULAR SIMULATIONS OF THE FORMATION PROCESS OF FULLERENE Yasutaka YAMAGUCHI and Shigeo MARUYAMA  

E-print Network

MOLECULAR SIMULATIONS OF THE FORMATION PROCESS OF FULLERENE Yasutaka YAMAGUCHI and Shigeo MARUYAMA. The formation mechanism of fullerene, a new type of carbon molecule with hollow caged structure, was studied, yielding the graphitic sheet for Tc fullerene-like caged structure for 2600 K

Maruyama, Shigeo

353

Molecular Packing and Solar Cell Performance in Blends of Polymers with a Bisadduct Fullerene  

E-print Network

Molecular Packing and Solar Cell Performance in Blends of Polymers with a Bisadduct Fullerene with the conventional electron acceptor phenyl-C61-butyric acid methyl ester (PCBM) to fullerenes with one to three indene adducts. We find that the multiadduct fullerenes with lower electron affinity improve

McGehee, Michael

354

Printed on November 11, 1993 Collective electronic excitations in carbon fullerene clusters  

E-print Network

Printed on November 11, 1993 Collective electronic excitations in carbon fullerene clusters David fullerenes in bulk quantities [2] has triggered an enormous interest in the scientific community in these systems. All fullerenes have a hollow graphitic shell structure composed of three-fold coordinated carbon

355

Leaving the fullerene road: presence and stability of sp chains in sp2  

E-print Network

Leaving the fullerene road: presence and stability of sp chains in sp2 carbon clusters and cluster carbon sp chains are essential ingredients for the formation of carbon fullerenes and nanotubes [6, 7 identified as a fundamental ingredient to transform sp structures into fullerenes and nanotubes

Powles, Rebecca

356

2 antiferromagnetic Heisenberg model on fullerene-type symmetry clusters N. P. Konstantinidis  

E-print Network

s= 1 2 antiferromagnetic Heisenberg model on fullerene-type symmetry clusters N. P. Konstantinidis for spins sitting on the vertices of clusters with the connectivity of fullerene molecules and a number the icosahedral Ih fullerene clusters but only plateaux with the most pronounced for n=28. The spatial symmetry

357

Relative stabilities of fullerene, cumulene, and polyacetylene structures for C,:n=18-60  

E-print Network

Relative stabilities of fullerene, cumulene, and polyacetylene structures for C,:n=18-60 Martin) primitive orbital basis set, contracted to [ 3~2~1. For n>32, the fullerenes are predicted to be the most of the fullerene structures are expected to be lowered even further as larger basis sets are employed. Hence

Simons, Jack

358

MONO1001 : A source for singly charged ions applied to the production of multicharged fullerene beams  

E-print Network

MONO1001 : A source for singly charged ions applied to the production of multicharged fullerene study of the production of multiply charged fullerene beams based on an ECR ion source. As collision, clusters and particularly of fullerenes, we have further developed the ion source ECRIS MONO10001

Boyer, Edmond

359

The development of nanoscale morphology in polymer:fullerene photovoltaic blends during solvent casting  

E-print Network

The development of nanoscale morphology in polymer:fullerene photovoltaic blends during solventsm00343c The power conversion efficiency in a conjugated polymer-functionalized fullerene bulk and a functionalized fullerene are of signifi- cant interest as systems to generate low-cost renewable-energy.1

Travis, Adrian

360

Nano Materials They sound like characters in a miniature fantasyland: fullerene, nanotube and quantum dot. But  

E-print Network

71 Nano Materials They sound like characters in a miniature fantasyland: fullerene, nanotube. Fullerenes are soccer-ball shaped molecules made of 60 carbon atoms, discovered in 1985 by Richard Smalley ­ primarily due to their high production costs ­ scientists believe that fullerenes may serve the basis

Maoz, Shahar

361

Ultrafast nonresonant third-order optical nonlinearity of fullerene-containing polyurethane films at telecommunication wavelengths  

E-print Network

Ultrafast nonresonant third-order optical nonlinearity of fullerene- containing polyurethane films a high load of 60 fullerene (C60) were prepared by reaction of the hydroxy-containing C60 fullerene films with the capacity to realize a high number density of C60 moieties. These resulted in more

362

Supramolecular Ordering in Oligothiophene-Fullerene Jennifer M. MacLeod,,|  

E-print Network

Supramolecular Ordering in Oligothiophene-Fullerene Monolayers Jennifer M. MacLeod,,| Oleksandr@emt.inrs.ca Abstract: Scanning tunneling microscopy (STM) of monolayers comprising oligothiophene and fullerene host C60 molecules, which form ordered domains with either one, two, or three fullerenes per cavity

363

Electric and magnetic properties of fullerenes Dan Jonsson, Patrick Norman, Kenneth Ruud,a)  

E-print Network

--namely C60 , C70 , and C84 . By investigating several fullerenes at an accurate uniform level of theory, we of the electric polarizability, the second hyperpolarizability, and the magnetizability of the fullerenes C70 of the magnetiz- ability of C60 .11,12 In this work we consider several fullerenes at the ab initio level

Helgaker, Trygve

364

Solubility of fullerenes in n -alkanoic acids C 2 –C 9  

Microsoft Academic Search

The solubility of fullerene C60 and a fullerene mixture [C60 (75%), C70 (24%), C76–80 (1%)] in linear alkanoic acids (C2–C9) was determined at 20°C. The solubilities of C60 and a fullerene mixture in carboxylic acids were examined in relation to the number of carbon atoms in the carboxylic acid.

K. N. Semenov; N. A. Charykov; A. K. Pyartman; V. A. Keskinov; V. V. Lishchuk; O. V. Arapov; N. I. Alekseev

2007-01-01

365

Molecular dynamics studies of the C(60) fullerene associations in aqueous solutions and a biological membrane  

NASA Astrophysics Data System (ADS)

The associative behavior of C60 fullerenes in water and a biological membrane was studied using computer molecular dynamics (MD) simulations. Multiple histogram method combined with umbrella sampling technique was used in calculating the fullerene pairwise free energy as a function of separation. It was observed that water wets the fullerene surface due to the high fullerene atomic density and therefore the strong fullerene-water dispersion interaction. Despite the fact of the insolubility of fullerenes, water was found to promote the dispersion of fullerenes in aqueous solution. A decomposition of the solvent-induced potential of mean force between fullerenes into entropy and energy (enthalpy) contributions revealed that the water-induced repulsion between fullerenes is energetic in origin, contrasting strongly to entropy-driven association observed for conventional non-polar solutes. The repulsive interaction was observed to decrease at elevated temperature due to an increasing contribution from a relatively weak entropy-driven association. The surface curvature effect was surveyed by studying nanoparticles of different shapes (fullerene, carbon nanotubes and graphenes) with similar chemical structures. As for a potential application of fullerene in biomedical systems, the poly(ethylene oxide) (PEO) modified fullerene derivative interactions in aqueous solution and the bare fullerene-fullerene interactions inside a dimyristoylphosphatidylcholine (DMPC) lipid bilayer were investigated. It shows that while the attraction between two PEO-modified fullerenes is stronger and longer range than that between two bare C60 fullerenes in aqueous solution, the PEO-modified fullerenes do not phase-separate in water but rather aggregate in chainlike clusters at concentrations where unmodified fullerenes completely phase-separate. The results of pairwise fullerene interactions inside a DMPC lipid shows that fullerenes, constrained in the same lateral plane, was found to be significantly less attractive inside the lipid bilayer than in an alkane melt of the same molecular weight as the surfactant tails. Contrasting to small hydrophobic solutes, fullerene situates off the bilayer center in favor of the stronger dispersion interactions with the denser region of the bilayer.

Li, Liwei

366

Thermal Science & Engineering Vol.3 No.3 (1995) A Molecular Dynamics Simulation for the Formation Mechanism of Fullerene*  

E-print Network

Mechanism of Fullerene* Shigeo MARUYAMA and Yasutaka YAMAGUCHI Abstract The formation mechanism of fullerene vaporization fullerene generation, we have calculated the clustering process starting from randomly located yielded the hollow caged carbon network which could be regarded as an imperfect fullerene. Intermediate

Maruyama, Shigeo

367

The Smallest Stable Fullerene, M@C28 (M = Ti, Zr, U) Gregory S. Boebinger, National High Magnetic Field Laboratory  

E-print Network

The Smallest Stable Fullerene, M@C28 (M = Ti, Zr, U) Gregory S. Boebinger, National High Magnetic fullerene. Note the close, but clear, separation between Ti@C28 and the smallest empty cage (C32), differing/z 3386385384383382381380 Ti@C28 C32 (Empty Cage) Fullerenes Buckminster Fullerenes ("Buckyballs") have

Weston, Ken

368

Search for suitable approximation methods for fullerene structure and relative stability studies: Case study with C50  

E-print Network

Search for suitable approximation methods for fullerene structure and relative stability studies of the best methods for fullerene structural prediction. In the predictions of relative stability of C50.1063/1.2335436 I. INTRODUCTION Since the discovery1 of the first fullerene member, C60, studies on fullerenes have

Wang, Yan Alexander

369

Distorted asymmetric cubic nanostructure of soluble fullerene crystals in efficient polymer:fullerene solar cells.  

PubMed

We found that 1-(3-methoxycarbonyl)propyl-1-phenyl-(6,6)C(61) (PCBM) molecules make a distorted asymmetric body-centered cubic crystal nanostructure in the bulk heterojunction films of reigoregular poly(3-hexylthiophene) and PCBM. The wider angle of distortion in the PCBM nanocrystals was approximately 96 degrees , which can be assigned to the influence of the attached side group to the fullerene ball of PCBM to bestow solubility. Atom concentration analysis showed that after thermal annealing the PCBM nanocrystals do preferentially distribute above the layer of P3HT nanocrystals inside devices. PMID:19722504

Kim, Youngkyoo; Nelson, Jenny; Zhang, Tong; Cook, Steffan; Durrant, James R; Kim, Hwajeong; Park, Jiho; Shin, Minjung; Nam, Sungho; Heeney, Martin; McCulloch, Iain; Ha, Chang-Sik; Bradley, Donal D C

2009-09-22

370

An analytical method for determination of fullerenes and functionalized fullerenes in soils with high performance liquid chromatography and UV detection.  

PubMed

Fullerenes are carbon-based nanomaterials expected to play a major role in emerging nanotechnology and produced at an increasing rate for industrial and household applications. In the last decade a number of novel compounds (i.e. fullerene derivatives) is being introduced into the market and specific analytical methods are needed for analytical purposes as well as environmental and safety issues. In the present work eight fullerenes (C60 and C70) and functionalized fullerenes (C60 and C70 exohedral-derivatives) were selected and a novel liquid chromatographic method was developed for their analysis with UV absorption as a method of detection. The resulting HPLC-UV method is the first one suitable for the analysis of all eight compounds. This method was applied for the analysis of fullerenes added to clayish, sandy and loess top-soils at concentrations of 20, 10 and 5 ?g kg(-1) and extracted with a combination of sonication and shaking extraction. The analytical method limits of detection (LoD) and limits of quantification (LoQ) were in the range of 6-10 ?g L(-1) and 15-24 ?g L(-1) respectively for the analytical solutions. The extraction from soil was highly reproducible with recoveries ranging from 47±5 to 71±4% whereas LoD and LoQ for all soils tested were of 3 ?g kg(-1) and 10 ?g kg(-1) respectively. No significant difference in the extraction performance was observed depending of the different soil matrices and between the different concentrations. The developed method can be applied for the study of the fate and toxicity of fullerenes in complex matrices at relatively low concentrations and in principle it will be suitable for the analysis of other types of functionalized fullerenes that were not included in this work. PMID:24356233

Carboni, Andrea; Emke, Erik; Parsons, John R; Kalbitz, Karsten; de Voogt, Pim

2014-01-01

371

Fullerene data mining using bibliometrics and database tomography  

PubMed

Database tomography (DT) is a textual database analysis system consisting of two major components: (1) algorithms for extracting multiword phrase frequencies and phrase proximities (physical closeness of the multiword technical phrases) from any type of large textual database, to augment (2) interpretative capabilities of the expert human analyst. DT was used to derive technical intelligence from a fullerenes database derived from the Science Citation Index and the Engineering Compendex. Phrase frequency analysis by the technical domain experts provided the pervasive technical themes of the fullerenes database, and phrase proximity analysis provided the relationships among the pervasive technical themes. Bibliometric analysis of the fullerenes literature supplemented the DT results with author/journal/institution publication and citation data. Comparisons of fullerenes results with past analyses of similarly structured near-earth space, chemistry, hypersonic/supersonic flow, aircraft, and ship hydrodynamics databases are made. One important finding is that many of the normalized bibliometric distribution functions are extremely consistent across these diverse technical domains and could reasonably be expected to apply to broader chemical topics than fullerenes that span multiple structural classes. Finally, lessons learned about integrating the technical domain experts with the data mining tools are presented. PMID:10661546

Kostoff; Braun; Schubert; Toothman; Humenik

2000-01-01

372

ON THE EXCITATION AND FORMATION OF CIRCUMSTELLAR FULLERENES  

SciTech Connect

We compare and analyze the Spitzer mid-infrared spectrum of three fullerene-rich planetary nebulae in the Milky Way and the Magellanic Clouds: Tc1, SMP SMC 16, and SMP LMC 56. The three planetary nebulae share many spectroscopic similarities. The strongest circumstellar emission bands correspond to the infrared active vibrational modes of the fullerene species C{sub 60} and little or no emission is present from polycyclic aromatic hydrocarbons. The strengths of the fullerene bands in the three planetary nebulae are very similar, while the ratios of the [Ne III]15.5 {mu}m/[Ne II]12.8 {mu}m fine structure lines, an indicator of the strength of the radiation field, are markedly different. This raises questions about their excitation mechanism and we compare the fullerene emission to fluorescent and thermal models. In addition, the spectra show other interesting and common features, most notably in the 6-9 {mu}m region, where a broad plateau with substructure dominates the emission. These features have previously been associated with mixtures of aromatic/aliphatic hydrocarbon solids. We hypothesize on the origin of this band, which is likely related to the fullerene formation mechanism, and compare it with modeled hydrogenated amorphous carbon that present emission in this region.

Bernard-Salas, J.; Jones, A. P. [Institut d'Astrophysique Spatiale, CNRS/Universite Paris-Sud 11, F-91405 Orsay (France); Cami, J.; Peeters, E.; Micelotta, E. R. [Department of Physics and Astronomy, The University of Western Ontario, London, ON N6A 3K7 (Canada); Groenewegen, M. A. T., E-mail: jbernard@ias.u-psud.fr [Royal Observatory of Belgium, Ringlaan 3, B-1180 Brussels (Belgium)

2012-09-20

373

Non-IPR fullerenes with properly closed shells.  

PubMed

Fullerenes with properly closed shells (having exactly half their adjacency eigenvalues strictly positive) are rare. All reported examples obey the isolated-pentagon rule (IPR), usually considered a necessary condition of overall stability, and fall into three series (leapfrogs, carbon cylinders and sporadic closed shells). It is shown here that there also exist fullerenes with properly closed shells that violate the IPR ('super-sporadic' fullerenes). All have negative LUMO eigenvalues of small magnitude. Exhaustive search finds four examples with 160 or fewer vertices: one isomer of C(120), two of C(156) and one of C(160). The first three contain single pentagon pairs and the fourth, a linear triple of fused pentagons. Larger examples can be found. A capping construction gives a series of properly closed shell fullerenes of C(3)/C(3v) symmetry, each with a single fully fused triple of pentagons and ?632 vertices. Tubular extension of the C(120) example leads a series of C(1)/C(s) isomer pairs with ?168 vertices, retaining the single pentagon adjacency and approaching isospectrality with increasing size. Both constructions are conjectured to lead to an infinite number of super-sporadic fullerenes. PMID:20936217

Fowler, Patrick W; Myrvold, Wendy

2010-11-28

374

From the "Brazuca" ball to Octahedral Fullerenes: Their Construction and Classification  

E-print Network

A simple cut-and-patch method is presented for the construction and classification for fullerenes belonging to the octahedral point groups, $O$ or $O_h$. In order to satisfy the symmetry requirement of the octahedral group, suitable numbers of four- and eight-member rings, in addition to the hexagons and pentagons, have to be introduced. An index consisting of four integers is introduced to specify an octahedral fullerenes. However, to specify an octahedral fullerene uniquely, we also found certain symmetry rules for these indices. Based on the transformation properties under the symmetry operations that an octahedral fullerene belongs to, we can identify four structural types of octahedral fullerenes.

Fan, Yuan-Jia

2014-01-01

375

Tuning the properties of polymer bulk heterojunction solar cells by adjusting fullerene size to control intercalation  

SciTech Connect

We demonstrate that intercalation of fullerene derivatives between the side chains of conjugated polymers can be controlled by adjusting the fullerene size and compare the properties of intercalated and nonintercalated poly(2,5-bis(3-hexadecylthiophen-2-yl)thieno[3,2-b]thiophene) (pBTTT):fullerene blends. The intercalated blends, which exhibit optimal solar-cell performance at 1:4 polymer:fullerene by weight, have better photoluminescence quenching and lower absorption than the nonintercalated blends, which optimize at 1:1. Understanding how intercalation affects performance will enable more effective design of polymer:fullerene solar cells.

Cates, N.C.

2010-02-24

376

Liposome Formulation of Fullerene-Based Molecular Diagnostic and Therapeutic Agents  

PubMed Central

Fullerene medicine is a new but rapidly growing research subject. Fullerene has a number of desired structural, physical and chemical properties to be adapted for biological use including antioxidants, anti-aging, anti-inflammation, photodynamic therapy, drug delivery, and magnetic resonance imaging contrast agents. Chemical functionalization of fullerenes has led to several interesting compounds with very promising preclinical efficacy, pharmacokinetic and safety data. However, there is no clinical evaluation or human use except in fullerene-based cosmetic products for human skincare. This article summarizes recent advances in liposome formulation of fullerenes for the use in therapeutics and molecular imaging. PMID:24300561

Zhou, Zhiguo

2013-01-01

377

Comparative process analysis of fullerene production by the arc and the radio-frequency discharge methods.  

PubMed

In this work, comparative analysis of processes in carbon arc and radio frequency (RF) plasma during fullerene synthesis has been presented. The kinetic model of fullerene formation developed earlier has been verified in both types of plasma reactors. The fullerene yield depended on carbon concentration, velocity of plasma flame and rotational temperature of C2 radicals predominantly. When mean rotational temperature of C2 radicals was 3000 K, the fullerene yield was the highest regardless of the type of used reactor. The zone of fullerene formation is larger significantly in RF plasma reactor compared to arc reactor. PMID:17450899

Markovi?, Z; Todorovi?-Markovi?, B; Mohai, I; Farkas, Z; Kovats, E; Szepvolgyi, J; Otasevi?, D; Scheier, P; Feil, S; Romcevi?, N

2007-01-01

378

Casimir-Polder interaction of fullerene molecules with surfaces  

E-print Network

We calculate the thermal Casimir--Polder potential of C60 and C70 fullerene molecules near gold and silicon nitride surfaces, motivated by their relevance for molecular matter wave interference experiments. We obtain the coefficients governing the asymptotic power laws of the interaction in the thermal, retarded and nonretarded distance regimes and evaluate the full potential numerically. The interaction is found to be dominated by electronic transitions, and hence independent of the internal temperature of the molecules. The contributions from phonon transitions, which are affected by the molecular temperature, give rise to only a small correction. Moreover, we find that the sizeable molecular line widths of thermal fullerenes may modify the nonretarded interaction, depending on the model used. Detailed measurements of the nonretarded potential of fullerene thus allow one to distinguish between different theories of incorporating damping.

Buhmann, Stefan Yoshi; Ellingsen, Simen Å; Hornberger, Klaus; Jacob, Andreas

2012-01-01

379

Casimir-Polder interaction of fullerene molecules with surfaces  

E-print Network

We calculate the thermal Casimir--Polder potential of C60 and C70 fullerene molecules near gold and silicon nitride surfaces, motivated by their relevance for molecular matter wave interference experiments. We obtain the coefficients governing the asymptotic power laws of the interaction in the thermal, retarded and nonretarded distance regimes and evaluate the full potential numerically. The interaction is found to be dominated by electronic transitions, and hence independent of the internal temperature of the molecules. The contributions from phonon transitions, which are affected by the molecular temperature, give rise to only a small correction. Moreover, we find that the sizeable molecular line widths of thermal fullerenes may modify the nonretarded interaction, depending on the model used. Detailed measurements of the nonretarded potential of fullerene thus allow one to distinguish between different theories of incorporating damping.

Stefan Yoshi Buhmann; Stefan Scheel; Simen Å. Ellingsen; Klaus Hornberger; Andreas Jacob

2012-02-09

380

Direct optical excitation of a fullerene-incarcerated metal ion  

E-print Network

The endohedral fullerene Er3N@C80 shows characteristic 1.5 micron photoluminescence at cryogenic temperatures associated with radiative relaxation from the crystal-field split Er3+ 4I13/2 manifold to the 4I15/2 manifold. Previous observations of this luminescence were carried out by photoexcitation of the fullerene cage states leading to relaxation via the ionic states. We present direct non-cage-mediated optical interaction with the erbium ion. We have used this interaction to complete a photoluminescence-excitation map of the Er3+ 4I13/2 manifold. This ability to interact directly with the states of an incarcerated ion suggests the possibility of coherently manipulating fullerene qubit states with light.

Mark A G Jones; Kyriakos Porfyrakis; G Andrew D Briggs; Robert A Taylor; Arzhang Ardavan

2006-04-18

381

An Abnormal Temperature Dependence of Conductivity in Fullerene Solids  

NASA Astrophysics Data System (ADS)

An abnormal temperature dependence of conductivity has been observed in some fullerene solids, C60, C70, and C60H36 within the temperature range 400-500 K. The temperature dependent conductivity measurements of these fullerene solids with various molecular diameters and moments of inertia indicate that the abnormal conductivity involves a molecular rotation effect in the fullerene solids. Conductivity measurements of the C60 solid samples prepared using various pressures indicate that the abnormal conductivity is also related to a variation of the energy band structure. We are proposing a model to explain this abnormal conductivity observed as that, a reversible annealing effect results in the releasing or trapping of holes in the deep energy levels induced by lattice defects. The contribution of these holes leads to the abnormal variation in the conductivity with temperature.

Sun, Yong; Onwona-Agyeman, Boateng; Miyasato, Tatsuro

2010-08-01

382

THE FORMATION OF COSMIC FULLERENES FROM AROPHATIC CLUSTERS  

SciTech Connect

Fullerenes have recently been identified in space and they may play a significant role in the gas and dust budget of various astrophysical objects including planetary nebulae (PNe), reflection nebulae, and H II regions. The tenuous nature of the gas in these environments precludes the formation of fullerene materials following known vaporization or combustion synthesis routes even on astronomical timescales. We have studied the processing of hydrogenated amorphous carbon (a-C:H or HAC) nanoparticles and their specific derivative structures, which we name ''arophatics'', in the circumstellar environments of young, carbon-rich PNe. We find that UV-irradiation of such particles can result in the formation of fullerenes, consistent with the known physical conditions in PNe and with available timescales.

Micelotta, Elisabetta R.; Cami, Jan; Peeters, Els; Fanchini, Giovanni [Department of Physics and Astronomy, University of Western Ontario, London, Ontario N6A 3K7 (Canada)] [Department of Physics and Astronomy, University of Western Ontario, London, Ontario N6A 3K7 (Canada); Jones, Anthony P.; Bernard-Salas, Jeronimo, E-mail: emicelot@uwo.ca [Institut d'Astrophysique Spatiale, CNRS/Universite Paris Sud, F-91405 Orsay (France)] [Institut d'Astrophysique Spatiale, CNRS/Universite Paris Sud, F-91405 Orsay (France)

2012-12-10

383

Photophysical properties of fullerene-dendron-pyropheophorbide supramolecules  

NASA Astrophysics Data System (ADS)

Two novel monofullerene-bis(pyropheophorbide a) complexes were synthesized and their photophysical properties were studied by using both steady-state and time-resolved techniques. It was revealed that in the pyropheophorbide a (pyroPheo)-C 60 molecular system (FP1) strong quenching of the first excited singlet state of the pyroPheo and, as result, dramatically decreasing of photosensitized singlet oxygen generation occurs by efficient photoinduced electron transfer to the fullerene molecule with a rate constant of 2.5 × 10 9 s -1. In contrast, the fullerene hexaadduct-bis(pyroPheo) system (FHP1), which possesses five diethyl malonate addends in the remaining octahedral positions, shows a high singlet oxygen quantum yield which is due to the reduced fullerene chromophore which is not a good electron acceptor anymore.

Ermilov, E. A.; Al-Omari, S.; Helmreich, M.; Jux, N.; Hirsch, A.; Röder, B.

2004-05-01

384

Properties of ion-bombarded fused quartz for integrated optics.  

PubMed

Development of techniques for production of carefully controlled, low-loss optical waveguides in solid dielectric materials is essential to development of integrated optical circuits for signal processing in future optical communications systems. Ion implantation offers an attractive possibility because of the refractive index and film thickness control possible by this technique. To evaluate this possibility we have investigated some of the optical properties of ion-bombarded fused quartz. A variety of ions ranging from helium ions to bismuth ions has been used. We have concentrated on refractive index and optical loss variations (on those implants into which a beam could be launched) as effected by (1) ion species and dose, (2) surface preparation, (3) surface temperature during bombardment, and (4) postbombardment annealing. This paper does not attempt to give an inclusive account of all the results obtained but principally discusses the best results so far, which are those using lithium ions. For lithium ion bombardment we have observed approximately linear variation of refractive index at 6328 A with dose n = n(0) + 2.1 x 10(-21)C, where n(0) is the prebombardment value (= 1.458 for fused quartz), and C is the ion concentration in ions/cm(3) (C < 2.2 x 10(19)). The optical absorption decreases significantly with increase in substrate temperature during implantation, and losses less than 0.2 dB/cm have been achieved. The refractive index change appears to be primarily due to disorder produced by the incident particles rather than a chemical doping effect as evidenced by postbombardment annealing studies. PMID:20119140

Standley, R D; Gibson, W M; Rodgers, J W

1972-06-01

385

Trifluoromethylation of fullerenes: kinetic and thermodynamic control.  

PubMed

We present a survey and theoretical interpretation of the experimental results on trifluoromethylation of fullerenes. A thermodynamic model has been developed to describe the C60/70(CF3)n condensed phase mixtures capable of free exchange of addends and, consequently, of isomerization and changing the degrees of addition. It was found that the purely thermodynamic model affords at least satisfactory prediction of composition of products even for apparently nonequilibrium syntheses. Special cases can be identified by means of detailed kinetic modeling based on the BEP approach, which includes stepwise energetic analysis of the possible trifluoromethylation sequences. This analysis reveals two types of reactions with remarkable difference in rates: direct trifluoromethylation and rearrangements of the CF3 groups. Whenever a particular group of compounds is interrelated through direct addition/abstraction of CF3 groups, it is more or less safe to assume that the said group is in equilibrium describable by the thermodynamic model. In the same time, the slower migration of addends is controlled kinetically, and interference of the sublimation processes frequently prevents its equilibration. Among the most illustrative examples of hindered formation via rearrangements in absence of sufficiently favorable direct trifluoromethylation pathways are certain isomers of the C3v-C60(CF3)18, C70(CF3)18, and C70(CF3)20 compounds. PMID:24147917

Ignat'eva, Daria V; Goryunkov, Alexey A; Ioffe, Ilya N; Sidorov, Lev N

2013-12-01

386

Endohedral Fullerenes for Organic Photovoltaic Devices  

SciTech Connect

So far, one of the fundamental limitations of organic photovoltaic (OPV) device power conversion efficiencies (PCEs) has been the low voltage output caused by a molecular orbital mismatch between the donor polymer and acceptor molecules. Here, we present a means of addressing the low voltage output by introducing novel trimetallic nitride endohedral fullerenes (TNEFs) as acceptor materials for use in photovoltaic devices. TNEFs were discovered in 1999 by Stevenson et al.; for the first time derivatives of the TNEF acceptor, Lu{sub 3}N{at}C{sub 80}, are synthesized and integrated into OPV devices. The reduced energy offset of the molecular orbitals of Lu{sub 3}N{at}C{sub 80} to the donor, poly(3-hexyl)thiophene (P3HT), reduces energy losses in the charge transfer process and increases the open circuit voltage (V{sub oc}) to 260 mV above reference devices made with [6,6]-phenyl-C{sub 61}-butyric methyl ester (C{sub 60}-PCBM) acceptor. PCEs >4% have been observed using P3HT as the donor material. This work clears a path towards higher PCEs in OPV devices by demonstrating that high-yield charge separation can occur with OPV systems that have a reduced donor/acceptor lowest unoccupied molecular orbital energy offset.

Ross, R. B.; Cardona, C. M.; Guldi, D. M.; Sankaranarayanan, S. G.; Reese, M. O.; Kopidakis, N.; Peete, J.; Walker, B.; ZBazan, G. C.; Van Keuren, E.; Holloway,; B. C.; Drees, M.

2009-03-01

387

Compositional changes in alloys during ion bombardment at elevated temperatures.  

SciTech Connect

Near-surface compositional changes in alloys during ion bombardment have been studied theoretically. The employed scheme operates with a stable target, and the effects of preferential sputtering, collisional mixing, radiation-enhanced diffusion, and Gibbsian and radiation-induced segregation are allowed for. High-fluence composition profiles were determined directly from a nonlinear integro-differential equation, after insertion of feasible input, by means of an efficient iteration procedure developed recently. The dependence of the composition profile on input parameters such as target temperature and defect mobility has been examined for Ni-Cu, Ni-Ge and Ni-Pd alloys and compared to experimental results.

Sckerl, M. W.; Lam, N. Q.; Sigmund, P.; Materials Science Division; Odense Univ.

1998-04-01

388

Propulsion of Ripples on Glass by Ion Bombardment  

SciTech Connect

The propulsion of surface ripples on SiO{sub 2} by an ion beam was investigated by in situ electron microscopy. The observed propagation of the ripples contradicts existing models for ion-beam-induced ripple development. A new model based on the Navier-Stokes relations for viscous flow in a thin layer is introduced. It includes inhomogeneous viscous flow, driven by spatial variations in the deposition of the energy of the ion beam. The model explains the observed reversed propagation. The hitherto unknown propulsion mechanism is important for understanding nanoscale pattern formation by ion bombardment.

Alkemade, P.F.A. [National Center of High Resolution Electron Microscopy and Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft (Netherlands)

2006-03-17

389

Enhanced resistance of single-layer graphene to ion bombardment  

SciTech Connect

We report that single-layer graphene on a SiO{sub 2}/Si substrate withstands ion bombardment up to {approx}7 times longer than expected when exposed to focused Ga{sup +} ion beam. The exposure is performed in a dual beam scanning electron microscope/focused ion beam system at 30 kV accelerating voltage and 41 pA current. Ga{sup +} ion flux is determined by sputtering a known volume of hydrogenated amorphous carbon film deposited via plasma-enhanced chemical vapor deposition.

Lopez, J. J. [East Los Angeles College, California 91754 (United States); Greer, F. [Jet Propulsion Laboratory, California 91109 (United States); Greer, J. R. [Division of Engineering and Applied Science, California Institute of Technology, California 91125 (United States)

2010-05-15

390

High efficiency of stable genetic transformation in Dendrobium via microprojectile bombardment  

Microsoft Academic Search

Several parameters affecting transient ?-glucuronidase (GUS) expression in protocorms of Dendrobium cv. Jaquelyn Thomas were examined using bombardment technique with pActin-1D plasmid. The GUS activity in Dendrobium protocorm was not significantly affected by size of the target, type of particles, and helium gas pressure. However, the\\u000a numbers of surviving tissues after bombardment were different. Transgenic orchids were established by bombardment

C. Suwanaketchanatit; J. Piluek; S. Peyachoknagul; P. S. Huehne

2007-01-01

391

Transformation of white spruce ( Picea glauca) somatic embryos by microprojectile bombardment  

Microsoft Academic Search

Cotyledonary somatic embryos of white spruce [Picea glauca (Moench) Voss] were subjected to microprojectile bombardment with a gene construct containing a gus::nptll fusion gene. Somatic embryos were used to re-induce the embryogenic tissue after bombardments. Histochemical assay using X-gluc as a substrate showed that all the embryos (100%) were GUS positive 48 h after bombardment. However, only thirteen out of

V. R. Bommineni; R. N. Chibbar; R. S. S. Datla; E. W. T. Tsang

1993-01-01

392

B38: an all-boron fullerene analogue  

NASA Astrophysics Data System (ADS)

Fullerene-like structures formed by elements other than carbon have long been sought. Finding all-boron (B) fullerene-like structures is challenging due to the geometrical frustration arising from competitions among various structural motifs. We report here the prediction of a B38 fullerene analogue found through first-principles swarm structure searching calculations. The structure is highly symmetric and consists of 56 triangles and four hexagons, which provide an optimal void in the center of the cage. Energetically, it is more favorable than the planar and tubular structures, and possesses an unusually high chemical stability: a large energy gap (~2.25 eV) and a high double aromaticity, superior to those of most aromatic quasi-planar B12 and double-ring B20 clusters. Our findings represent a key step forward towards to the understanding of structures of medium-sized B clusters and map out the experimental direction of the synthesis of an all-B fullerene analogue.Fullerene-like structures formed by elements other than carbon have long been sought. Finding all-boron (B) fullerene-like structures is challenging due to the geometrical frustration arising from competitions among various structural motifs. We report here the prediction of a B38 fullerene analogue found through first-principles swarm structure searching calculations. The structure is highly symmetric and consists of 56 triangles and four hexagons, which provide an optimal void in the center of the cage. Energetically, it is more favorable than the planar and tubular structures, and possesses an unusually high chemical stability: a large energy gap (~2.25 eV) and a high double aromaticity, superior to those of most aromatic quasi-planar B12 and double-ring B20 clusters. Our findings represent a key step forward towards to the understanding of structures of medium-sized B clusters and map out the experimental direction of the synthesis of an all-B fullerene analogue. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr01846j

Lv, Jian; Wang, Yanchao; Zhu, Li; Ma, Yanming

2014-09-01

393

Optical limiting with C(60) and other fullerenes.  

PubMed

In view of a possible application in optical limiting devices for protection against laser radiation, at the Defence Research Establishment Valcartier we have studied the nonlinear transmission properties of fullerenes. The study involved C(60), C(70), C(76), C(84), several derivatives of C(60), and a variety of solvents. The nonlinear measurements were made with 7-ns pulses at 532 nm from a N-d:YAG laser. For optical limiting applications, solutions of C(60) yielded better results than the other fullerenes, with a solution of C(60) in chlorobenzene being marginally the best. PMID:18264303

Vincent, D; Cruickshank, J

1997-10-20

394

Optical limiting with C 60 and other fullerenes  

NASA Astrophysics Data System (ADS)

In view of a possible application in optical limiting devices for protection against laser radiation, at the Defence Research Establishment Valcartier we have studied the nonlinear transmission properties of fullerenes. The study involved C 60 , C 70 , C 76 , C 84 , several derivatives of C 60 , and a variety of solvents. The nonlinear measurements were made with 7-ns pulses at 532 nm from a N-d:YAG laser. For optical limiting applications, solutions of C 60 yielded better results than the other fullerenes, with a solution of C 60 in chlorobenzene being marginally the best.

Vincent, Denis; Cruickshank, James

1997-10-01

395

Graph-theoretic independence as a predictor of fullerene stability  

NASA Astrophysics Data System (ADS)

The independence number of the graph of a fullerene, the size of the largest set of vertices such that no two are adjacent (corresponding to the largest set of atoms of the molecule, no pair of which are bonded), appears to be a useful selector in identifying stable fullerene isomers. The experimentally characterized isomers with 60, 70 and 76 atoms uniquely minimize this number among the classes of possible structures with, respectively, 60, 70 and 76 atoms. Other experimentally characterized isomers also rank extremely low with respect to this invariant. These findings were initiated by a conjecture of the computer program Graffiti.

Fajtlowicz, S.; Larson, C. E.

2003-08-01

396

Charge Transport in Amorphous Polythiophene-Fullerene Blends  

NASA Astrophysics Data System (ADS)

Energy-filtered transmission electron microscopy studies revealed that amorphous mixed phases are ubiquitous within mesostructured polythiophene/fullerene mixtures. Nevertheless, the role of mixing within nanophases on charge transport of organic semiconductor mixtures is not fully understood. We have examined the electron mobility in amorphous blends of poly(3-hexylthiophene) and phenyl-C61-butyric acid methyl ester. Our studies reveal that the miscibility of the components strongly affects electron transport within amorphous blends. Immiscibility promotes efficient electron transport by promoting percolating pathways within organic semiconductor mixtures. As a consequence, partial miscibility may be important for efficient charge transport in polythiophene/fullerene mixtures and organic solar cell performance.

Vakhshouri, Kiarash; Kozub, Derek; Wang, Chenchen; Salleo, Alberto; Gomez, Enrique

2012-02-01

397

Efficient resistive memory effect on SrTiO3 by ionic-bombardment  

NASA Astrophysics Data System (ADS)

We show that ionic-bombardment leads to noticeable resistive memory effect on pure SrTiO3 (STO). In an Ar-bombarded STO crystal, two orders of resistance difference was observed between the high and low resistive states. We found that Ar-bombardment is more efficient than thermal-reduction in creating memory-effective oxygen vacancies. One of the advantages of the ionic-bombardment scheme is that it can be easily combined with lithographic processes to create spatially selective memory effect.

Gross, Heiko; Oh, Seongshik

2011-08-01

398

Desorption of nanoclusters from gold nanodispersed layers by 72 keV Au 400 ions: Experiment and molecular dynamics simulation  

NASA Astrophysics Data System (ADS)

The interaction of 72 keV Au 400 ions (with a diameter of approximately 2 nm) with nanodispersed gold targets has been studied. These interactions are dominated by elastic collisions. The gold nanodispersed target with 2-12 nm nanoislets was bombarded with a fluence of 1.7 × 10 12 ions/cm 2. The desorbed nanoclusters were collected on carbon foils supported by TEM-grids. Intact 29 nm gold nanoclusters were found on the collectors. The desorption yield (normalized to the total cross-section of the projectile-cluster interaction) was estimated to be 0.62 nanocluster/projectile. Preliminary estimates were made using molecular dynamic simulations for comparison with the experimental results.

Baranov, I.; Della-Negra, S.; Domaratsky, V.; Chemezov, A.; Novikov, A.; Obnorsky, V.; Pautrat, M.; Anders, Chr.; Urbassek, H. M.; Wien, K.; Yarmiychuk, S.; Zhurkin, E.

2008-05-01

399

ETFE polymer bombarded with 1 MeV proton  

NASA Astrophysics Data System (ADS)

The ethylenetetrafluoroethylene (ETFE) is a polymer formed by alternating ethylene and tetrafluoroethylene segments. It has high impact resistance and useful mechanical properties. ETFE can be used as components of pumps, valves, tie wraps, and electrical components. It can also be applied in the field of medical physics as intra venous catheters and as radiation dosimeter. When a material is exposed to the ionizing radiation, it suffers damage that depends on the type, energy and intensity of the radiation. In order to determine the radiation damage mechanism, ETFE films were bombarded with 1 MeV protons to the fluence between 1 × 10 11 and 1 × 10 16 protons/cm 2 and the chemical species emitted during the bombardment were measured with residual gas analysis (RGA) and show that HF gas is the entity preferentially emitted. Optical absorption photospectrometry (OAP) and attenuated total reflectometry fourier transform infrared (ATR-FTIR) shows quantitative chemical evidence of the damage. Our results show that damage is detectable at low proton fluence, but damage that can compromise the application in dosimetry occurs only for fluence greater than 10 14 protons/cm 2.

Parada, M. A.; de Almeida, A.; Muntele, I.; Muntele, C.; Delalez, N.; Ila, D.

2005-12-01

400

Generation of singlet oxygen in fullerene-containing media: 1. Photodesorption of singlet oxygen from fullerene-containing surfaces  

SciTech Connect

It is shown that upon irradiation of fullerene-containing surfaces by laser or flashlamp pulses, oxygen adsorbed by these surfaces efficiently escapes to the gas phase. The observation of luminescence pulses in the spectral region of 762 and 1268 nm confirms the presence of oxygen molecules in the excited singlet state in the desorbed oxygen. The conditions for optimisation of the efficiency of singlet-oxygen production are studied. It is shown that singlet oxygen at the concentration sufficient for obtaining operation of a fullerene-oxygen-iodine laser can be produced in this way. (laser applications and other topics in quantum electronics)

Belousova, I M; Belousov, V P; Danilov, O B; Ermakov, A V; Kiselev, V M; Kislyakov, I M; Sosnov, E N [Institute for Laser Physics, Federal State Unitary Enterprise, Scientific and Industrial Corporation 'Vavilov State Optical Institute', St. Petersburg (Russian Federation)

2008-03-31

401

Modifications of magnetic anisotropy and magnetization reversal in [Co0.4 nm/Pd0.7 nm]50 multilayers induced by 10 keV-He ion bombardment  

NASA Astrophysics Data System (ADS)

[Co0.4 nm/Pd0.7 nm]50 multilayers with Pd film thicknesses in the first ferromagnetic maximum of interlayer exchange coupling display almost purely perpendicular-to-plane anisotropy and labyrinth stripe domain patterns in remanence. Their magnetization reversal is characterized by domain nucleation starting at a defined field HN and domain wall movement in a defined magnetic field range. The modification of the magnetization reversal by 10 keV He ion bombardment due to the reduced magnetic anisotropy has been investigated by polar magneto-optical Kerr effect, by vibrating sample magnetometry, and by magnetic force microscopy at room temperature. It is shown that the ion bombardment creates and increases areas with ferromagnetic in-plane anisotropy and proportions of the sample showing superparamagnetism, the latter predominantly in the deeper layers.

Ehresmann, Arno; Hellwig, Olav; Buhl, Oliver; David Müglich, Nicolas; Weis, Tanja; Engel, Dieter

2012-09-01

402

Atom penetration from a thin film into the substrate during sputtering by polyenergetic Ar{sup +} ion beam with mean energy of 9.4 keV  

SciTech Connect

Penetration of alien atoms (Be, Ni) into Be, Al, Zr, Si and diamond was investigated under Ar{sup +} ion bombardment of samples having thermally evaporated films of 30--50 nm. Sputtering was carried out using a wide energy spectrum beam of Ar{sup +} ions of 9.4 keV to dose D = 1 {times} 10{sup 16}--10{sup 19} ion/cm{sup 2}. Implanted atom distribution in the targets was measured by Rutherford backscattering spectrometry (RBS) of H{sup +} and He{sup +} ions with energy of 1.6 MeV as well as secondary ion mass-spectrometry (SIMS). During the bombardment, the penetration depth of Ar atoms increases with dose linearly. This depth is more than 3--20 times deeper than the projected range of bombarding ions and recoil atoms. This is a deep action effect. The analysis shows that the experimental data for foreign atoms penetration depth are similar to the data calculated for atom migration through the interstitial site in a field of internal (lateral) compressive stresses created in the near-surface layer of the substrate as a result of implantation. Under these experimental conditions atom ratio r{sub i}/r{sub m} (r{sub i} -- radius of dopant, r{sub m} -- radius target of substrate) can play a principal determining role.

Kalin, B.A.; Gladkov, V.P.; Volkov, N.V.; Sabo, S.E. [Moscow Engineering Physics Inst. (Russian Federation)

1995-12-31

403

On the Excitation and Formation of Circumstellar Fullerenes  

E-print Network

We compare and analyze the Spitzer mid-infrared spectrum of three fullerene-rich planetary nebulae in the Milky Way and the Magellanic Clouds; Tc1, SMP SMC16, and SMP LMC56. The three planetary nebulae share many spectroscopic similarities. The strongest circumstellar emission bands correspond to the infrared active vibrational modes of the fullerene species C60 and little or no emission is present from Polycyclic Aromatic Hydrocarbons (PAHs). The strength of the fullerene bands in the three planetary nebulae is very similar, while the ratio of the [NeIII]15.5um/[NeII]12.8um fine structure lines, an indicator of the strength of the radiation field, is markedly different. This raises questions about their excitation mechanism and we compare the fullerene emission to fluorescent and thermal models. In addition, the spectra show other interesting and common features, most notably in the 6-9um region, where a broad plateau with substructure dominates the emission. These features have previously been associated wi...

Bernard-Salas, J; Peeters, E; Jones, A P; Micelotta, E R; Groenewegen, M A T

2012-01-01

404

Stabilized-jellium description of neutral and multiply charged fullerenes  

E-print Network

A description of neutral and multiply charged fullerenes is proposed based on a stabilized jellium (structureless pseudopotential) approximation for the ionic background and the local density approximation for the sigma and pi valence electrons. A recently developed shell-correction method is used to calculate total energies and properties of both the neutral and multiply charged anionic and cationic fullerenes. The effect of the icosahedral symmetry is included perturbatively. The calculated single-particle energy level spectrum of C_60 is in good correspondence with experimentally measured ones and previous self-consistent local-density-approximation calculations. For the multiply charged fullerenes, we calculate microscopically the charging energies for up to 12 excess charges. A semiclassical interpretation of these results is developed, which views the fullerenes as Coulomb islands possessing a classical capacitance. The calculated values for the first ionization potential and the first electron affinity agree well with the experimental ones. Our calculations support the results from charge transfer bracketing experiments and from direct ionization experiments through electron impact. The doubly charged negative ion is found to be a very long-lived metastable species, in agreement with observations.

Constantine Yannouleas; Uzi landman

2009-10-18

405

B38: an all-boron fullerene analogue.  

PubMed

Fullerene-like structures formed by elements other than carbon have long been sought. Finding all-boron (B) fullerene-like structures is challenging due to the geometrical frustration arising from competitions among various structural motifs. We report here the prediction of a B38 fullerene analogue found through first-principles swarm structure searching calculations. The structure is highly symmetric and consists of 56 triangles and four hexagons, which provide an optimal void in the center of the cage. Energetically, it is more favorable than the planar and tubular structures, and possesses an unusually high chemical stability: a large energy gap (?2.25 eV) and a high double aromaticity, superior to those of most aromatic quasi-planar B12 and double-ring B20 clusters. Our findings represent a key step forward towards to the understanding of structures of medium-sized B clusters and map out the experimental direction of the synthesis of an all-B fullerene analogue. PMID:24993287

Lv, Jian; Wang, Yanchao; Zhu, Li; Ma, Yanming

2014-10-21

406

Generation Mechanism of Carbon Cluster, Fullerene, and Metallofullerene  

E-print Network

-scale of the simulation resulted the perfect Ih-C60 structure through Stone-Wales transformations. A fullerene formation C60 and a trace of C70; well-known even atom mass with intense peaks at C60 and C70. Qualitatively temperature condition. When the control temperature was at Tc = 3000 K, imperfect caged clusters like C60

Maruyama, Shigeo

407

Uptake and distribution of fullerenes in human mast cells  

PubMed Central

Fullerenes are carbon cages of variable size that can be derivatized with various side chain moieties resulting in compounds that are being developed into nanomedicines. While fullerene use in several pre-clinical in vitro and in vivo models of disease has demonstrated their potential as diagnostic and therapeutic agents, little is known about how they enter cells, what organelles they target, and the time course for their cellular deposition. Fullerenes (C70) that have previously been shown to be potent inhibitors of mast cell (MC)-mediated allergic inflammation were conjugated with Texas Red (TR) and used in conjunction with confocal microscopy to determine mechanisms of uptake, the organelle localization, and the duration they can be detected in situ. We show C70-TR are non-specifically endocytosed into MC where they are shuttled throughout the cytoplasm, lysosomes, mitochondria, and into endoplasmic reticulum at different times. No nuclear or secretory granule localization was observed. The C70-TR remained detectable within cells at one week. These studies show MC endocytose fullerenes where they are shuttled to organelles involved with calcium and reactive oxygen species (ROS) production which may explain their efficacy as cellular inhibitors. PMID:20138243

Dellinger, Anthony; Zhou, Zhiguo; Norton, Sarah K.; Lenk, Robert; Conrad, Daniel; Kepley, Christopher L.

2010-01-01

408

Response of Carbon Fullerene Clusters to Electromagnetic Fields (*).  

E-print Network

for the C60 molecule and other fullerenes with a similar topology. In the following, I will address two of C20 , C60 and C70 to multipolar fields will be addressed in sect. 3, and the inelastic scattering of electrons from C60 and C70 clusters will be summarized in sect. 4. Main conclusions will be present- ed

409

Sensitization of fullerenes by covalent attachment of a diketopyrrolopyrrole chromophore  

E-print Network

by its C70 analogue, [6,6]-phenyl-C71-butyric acid methyl ester (PC70BM). Another strategy to excite absorbs and then transfers the excitation energy to C60.10­13 Noteworthy are also conjugatesSensitization of fullerenes by covalent attachment of a diketopyrrolopyrrole chromophore Natalie

Candea, George

410

Photoionization and Photofragmentation of Carbon Fullerene Molecular Ions  

NASA Astrophysics Data System (ADS)

Cross sections are reported for single and double photoionization accompanied by the loss of as many as seven pairs of C atoms of C60 + and C70+ fullerene molecular ions in the photon energy range 18 eV to 150 eV. These measurements were performed at the Advanced Light Source (ALS) by merging a mass-selected ion beam with a beam of monochromatized synchrotron radiation. Threshold energies were determined for the formation of doubly and triply charged fragment ions from parent ions C60+ and C70+. The energy dependences of cross-sections for direct photoionization yielding C60 2+ and C702+ are compared with those for forming different doubly and triply charged fullerene fragment ions. Two-dimensional product ion scans were measured and quantified at four discrete photon energies: 35 eV, 65 eV, 105 eV and 140 eV, in the vacuum ultraviolet region, providing a comprehensive mapping of the product channels involving single ionization of fullerene ions C60+ and C 70+ accompanied by fragmentation. Since fullerenes are composed of even numbers of carbon atoms, the fragmentation occurs by the loss of differing numbers of carbon atom pairs. In addition to pure ionization, fragmentation product channels become relatively more important at higher photon energies.

Baral, Kiran Kumar

411

UV photostability of PMMA-C60 fullerene composition  

NASA Astrophysics Data System (ADS)

Thermal decomposition of pure poly(methyl methacrylate) (PMMA) and its composition with C60 fullerene before and after UV irradiation has been studied by thermodesorption mass spectrometry (TDMS). It is established that low-temperature depolymerization of UV-irradiated PMMA is suppressed in its composition with C60. Possible molecular stabilization mechanisms are discussed.

Pozdnyakov, O. F.; Popov, E. O.; Pozdnyakov, A. O.

2012-12-01

412

Fullerene-Based Symmetry in Hibiscus rosa-sinensis Pollen  

PubMed Central

The fullerene molecule belongs to the so-called super materials. The compound is interesting due to its spherical configuration where atoms occupy positions forming a mechanically stable structure. We first demonstrate that pollen of Hibiscus rosa-sinensis has a strong symmetry regarding the distribution of its spines over the spherical grain. These spines form spherical hexagons and pentagons. The distance between atoms in fullerene is explained applying principles of flat, spherical, and spatial geometry, based on Euclid’s “Elements” book, as well as logic algorithms. Measurements of the pollen grain take into account that the true spine lengths, and consequently the real distances between them, are measured to the periphery of each grain. Algorithms are developed to recover the spatial effects lost in 2D photos. There is a clear correspondence between the position of atoms in the fullerene molecule and the position of spines in the pollen grain. In the fullerene the separation gives the idea of equal length bonds which implies perfectly distributed electron clouds while in the pollen grain we suggest that the spines being equally spaced carry an electrical charge originating in forces involved in the pollination process. PMID:25003375

Andrade, Kleber; Guerra, Sara; Debut, Alexis

2014-01-01

413

Optical limiting with C 60 and other fullerenes  

Microsoft Academic Search

In view of a possible application in optical limiting devices for protection against laser radiation, at the Defence Research Establishment Valcartier we have studied the nonlinear transmission properties of fullerenes. The study involved C 60 , C 70 , C 76 , C 84 , several derivatives of C 60 , and a variety of solvents. The nonlinear measurements were

Denis Vincent; James Cruickshank

1997-01-01

414

Thermochemistry of Pt-Fullerene Complexes: Semiempirical Study  

NASA Astrophysics Data System (ADS)

Modified Neglect of Differential Overlap (MNDO) and MNDO/d based semiempirical methods are widely employed to explore structure and thermochemistry of molecular systems. In this work, the AM1/d method has been parametrized for systems containing platinum. The proposed scheme delivers excellent performance for binding energies of Pt complexes with ethylene and large ? conjugated hydrocarbons. The estimated bond energies accurately reproduce the results of MP4(SDQ) calculations and show significant improvement over DFT (B3LYP and M05) data. We apply the AM1/d scheme to explore the structure and thermochemistry of several Pt compounds with C60 and C70. The calculated binding energies of bare Pt atoms and [Pt(PH3)2] units to the fullerenes are 75 and 45 kcal/mol, respectively. We find that coordination of a single metal center to C60 activates the fullerene cage making subsequent coordination of Pt more favorable. The bond energy [C60-PtC60] is calculated to be 65 kcal/mol. The estimated reaction enthalpies are useful for exploring the stability of PtxC60 polymer systems and their interaction with phosphines. AM1/d predicts a very low barrier to rotation of the coordinated fullerenes in [Pt(C60)2]. The AM1/d scheme is computationally very efficient and can be employed to obtain fast quantitative estimates for binding energies and structural parameters of Pt complexes with large ? conjugated systems like fullerenes and carbon nanotubes.

Voityuk, Alexander A.

2009-07-01

415

The Electronic Structure of Transition Metal Coated Fullerenes  

NASA Astrophysics Data System (ADS)

Clusters composed of fullerene molecules with an outer shell of transition metal atoms in the composition C_60M_62 (M being a transition metal) have been produced with laser vaporisation techniques(F. Tast, N. Malinowski, S. Frank, M. Heinebrodt, I.M.L. Billas, and T. P. Martin, Z. Phys D 40), 351 (1997).. We have studied several of these very large systems with a parallel version of the all-electron NRLMOL cluster code. Optimized geometries of the metal encased fullerenes C_60Ti_62 and C_60V_62 are presented along with their HOMO-LUMO gaps, electron affinities, ionization energies, and cohesive energies. We compare the stability of these clusters to relaxed met-car structures (e.g. Ti_8C_12) and to relaxed rocksalt metal-carbide fragments (TiC)n with n=8 and 32. In addition to metal-coated fullerenes we consider the possibility of a trilayered structure consisting of a small shell of metal atoms enclosed by a metal coated fullerene. The nature of bonding in these systems is analyzed by studying the electronic charge distributions.

Patton, David C.; Pederson, Mark R.; Kaxiras, Efthimios

1998-03-01

416

Simulation of energetic particle-surface impacts involving fullerenes  

Microsoft Academic Search

The impacts of C60 fullerenes with graphite surfaces and the impact of Ar ions with fullerite are studied by means of molecular dynamics simulations. For the case of the C60 impacts on graphite, surface waves spread from the point of impact and the molecule bounces off the surface at energies up to a few hundred eV. At higher energies the

Roger Smith; Steve Hobday; Roger Webb

1997-01-01

417

Single or functionalized fullerenes interacting with heme group  

NASA Astrophysics Data System (ADS)

The heme group is responsible for iron transportation through the bloodstream, where iron participates in redox reactions, electron transfer, gases detection etc. The efficiency of such processes can be reduced if the whole heme molecule or even the iron is somehow altered from its original oxidation state, which can be caused by interactions with nanoparticles as fullerenes. To verify how such particles alter the geometry and electronic structure of heme molecule, here we report first principles calculations based on density functional theory of heme group interacting with single C60 fullerene or with C60 functionalized with small functional groups (-CH3, -COOH, -NH2, -OH). The calculations shown that the system heme + nanoparticle has a different spin state in comparison with heme group if the fullerene is functionalized. Also a functional group can provide a stronger binding between nanoparticle and heme molecule or inhibit the chemical bonding in comparison with single fullerene results. In addition heme molecule loses electrons to the nanoparticles and some systems exhibited a geometry distortion in heme group, depending on the binding energy. Furthermore, one find that such nanoparticles induce a formation of spin up states in heme group. Moreover, there exist modifications in density of states near the Fermi energy. Although of such changes in heme electronic structure and geometry, the iron atom remains in the heme group with the same oxidation state, so that processes that involve the iron might not be affected, only those that depend on the whole heme molecule.

Costa, Wallison Chaves; Diniz, Eduardo Moraes

2014-09-01

418

Effect of a Fullerene Water Suspension on Bacterial  

E-print Network

cells showed slightly increased phase transition temperatures (Tm) and increased membrane fluidity for cells grown in the presence of high, growth-inhibiting concentrations (0.5 mg L-1) of nC60. B. subtilisEffect of a Fullerene Water Suspension on Bacterial Phospholipids and Membrane Phase Behavior J I

Alvarez, Pedro J.

419

Desorption of large organic molecules induced by keV projectiles  

NASA Astrophysics Data System (ADS)

In order to understand the emission of organic molecules in sputtering, classical molecular dynamics (MD) is used to model the 5 keV Ar atom bombardment of polystyrene oligomers adsorbed on Ag{1 1 1}. The analysis of the results shows that a significant fraction of the trajectories generates high action events in the sample. These events are characterized by the simultaneous motion of several hundreds of substrate atoms and, oftentimes, by high emission yields of substrate atoms, clusters and polystyrene molecules. Collision trees representing the energetic part of the cascades confirm that high sputtering yields of molecules occur when a large portion of the primary particle energy is quickly dissipated in the upper layers of the silver substrate. This class of events where high action occurs in the surface region might explain the ejection of organic species with a mass of several kilodaltons such as biomolecules and synthetic polymers. In the simulation, these events are capable of desorbing polystyrene molecules of ˜2 kDa.

Delcorte, A.; Garrison, B. J.

2001-06-01

420

Dynamic analysis and evolution of mixed materials bombarded with multiple T. Sizyuk *, A. Hassanein  

E-print Network

Dynamic analysis and evolution of mixed materials bombarded with multiple ions beams T. Sizyuk *, A dynamic changing of materials composition as result of multiple ion beams bombardment and target atoms material atoms, dynamic surface evolution/modification, thermal diffusion, and surface segregation

Harilal, S. S.

421

Molecular dynamics simulation of Argon-atom bombardment on graphene sheets  

Microsoft Academic Search

By a molecular dynamics method and using different incident energy and particle density, we calculated the argon-atom bombardment on a graphene sheet. The results show that, the damage of the bombardment on the graphene sheet depends not only on the incident energy but also on the particle density of argon atoms. To compare and analyze the effect of the incident

Xiao-Lin Wei; Kai-Wang Zhang; Ru-Zhi Wang; Wen-Liang Liu; Jian-Xin Zhong

2010-01-01

422

An efficient particle bombardment system for the genetic transformation of asparagus ( Asparagus officinalis L.)  

Microsoft Academic Search

The microprojectile bombardment method was used to transfer DNA into embryogenic callus of asparagus (Asparagus officcinalis L.) and to produce stably transformed asparagus plants. Embryogenic callus, derived from UC 157 and UC72 asparagus cultivars, was bombarded with tungsten particles coated with plasmid DNA that contained genes encoding hygromycin phosphotransferase, phosphinothricin acetyl transferase and ß-glucuronidase. Putatively transformed calli were identified from

Jose Luis Cabrera-Ponce; Liliana López; Nacyra Assad-Garcia; Consuelo Medina-Arevalo; Ana Maria Bailey; Luis Herrera-Estrella

1997-01-01

423

Transgenic perennial ryegrass ( Lolium perenne) plants from microprojectile bombardment of embryogenic suspension cells  

Microsoft Academic Search

Transgenic forage-type perennial ryegrass (Lolium perenne L.) plants have been obtained by microprojectile bombardment of embryogenic suspension cells using a chimeric hygromycin phosphotransferase (hph) gene construct driven by rice Actl 5? regulatory sequences. Parameters for the bombardment of embryogenic suspension cultures with the particle inflow gun were partially optimized using transient expression assays of a chimeric ?-glucuronidase (gusA) gene driven

Germán Spangenberg; Zeng-yu Wang; Xinli Wu; Jutta Nagel; Ingo Potrykus

1995-01-01

424

Ion-trap electrode preparation with Ne$^+$ bombardment  

E-print Network

We describe an ex-situ surface-cleaning procedure that is shown to reduce motional heating from ion-trap electrodes. This precleaning treatment, to be implemented immediately before the final assembly and vacuum processing of ion traps, removes surface contaminants remaining after the electrode-fabrication process. We incorporate a multi-angle ion-bombardment treatment intended to clean the electrode surfaces and interelectrode gaps of microfabricated traps. This procedure helps to minimize redeposition in the gaps between electrodes that can cause electrical shorts. We report heating rates in a stylus-type ion trap prepared in this way that are lower by one order of magnitude compared to a similar untreated stylus-type trap using the same experimental setup.

McKay, K S; Colombe, Y; Jördens, R; Wilson, A C; Slichter, D H; Allcock, D T C; Leibfried, D; Wineland, D J; Pappas, D P

2014-01-01

425

Bombarding Cancer: Biolistic Delivery of therapeutics using Porous Si Carriers  

PubMed Central

A new paradigm for an effective delivery of therapeutics into cancer cells is presented. Degradable porous silicon carriers, which are tailored to carry and release a model anti-cancer drug, are biolistically bombarded into in-vitro cancerous targets. We demonstrate the ability to launch these highly porous microparticles by a pneumatic capillary gene gun, which is conventionally used to deliver cargos by heavy metal carriers. By optimizing the gun parameters e.g., the accelerating gas pressure, we have successfully delivered the porous carriers, to reach deep targets and to cross a skin barrier in a highly spatial resolution. Our study reveals significant cytotoxicity towards the target human breast carcinoma cells following the delivery of drug-loaded carriers, while administrating empty particles results in no effect on cell viability. The unique combination of biolistics with the temporal control of payload release from porous carriers presents a powerful and non-conventional platform for designing new therapeutic strategies. PMID:23975675

Zilony, Neta; Tzur-Balter, Adi; Segal, Ester; Shefi, Orit

2013-01-01

426

Uses of ion bombardment in thin-film deposition  

SciTech Connect

Use of plasma- and ion-beam-modified surfaces and surface coatings in continually expanding in engineering disciplines. The purpose of these modifications and treatments is to impart favorable properties, such as wear resistance and lubricity, to the surfaces, while at the same time retaining the strength or toughness of the bulk materials. Energetic-ion bombardment can be used to modify the structural and chemical properties of surfaces or applied coatings. Ion-implantation has been used for many years, and recently, other surface-modification techniques, among them ion-beam mixing and ion-beam-assisted deposition, have attracted attention because they permit application of highly adherent lubricious and wear-resistant films. In this paper, ion-beam techniques are described from the viewpoint of ion-surface interactions, and some avenues for the engineering of tribological surfaces are presented. 100 refs., 4 figs.

Erck, R.A.; Fenske, G.R.; Erdemir, A.

1990-10-01

427

Effect of fullerene tris-adducts on the photovoltaic performance of P3HT:fullerene ternary blends.  

PubMed

Fullerene tris-adducts have the potential of achieving high open-circuit voltages (V(OC)) in bulk heterojunction (BHJ) polymer solar cells (PSCs), because their lowest unoccupied molecular orbital (LUMO) level is higher than those of fullerene mono- and bis-adducts. However, no successful examples of the use of fullerene tris-adducts as electron acceptors have been reported. Herein, we developed a ternary-blend approach for the use of fullerene tris-adducts to fully exploit the merit of their high LUMO level. The compound o-xylenyl C60 tris-adduct (OXCTA) was used as a ternary acceptor in the model system of poly(3-hexylthiophene) (P3HT) as the electron donor and the two soluble fullerene acceptors of OXCTA and fullerene monoadduct (o-xylenyl C60 monoadduct (OXCMA), phenyl C61-butyric acid methyl ester (PCBM), or indene-C60 monoadduct (ICMA)). To explore the effect of OXCTA in ternary-blend PSC devices, the photovoltaic behavior of the device was investigated in terms of the weight fraction of OXCTA (W(OXCTA)). When W(OXCTA) is small (<0.3), OXCTA can generate a synergistic bridging effect between P3HT and the fullerene monoadduct, leading to simultaneous enhancement in both V(OC) and short-circuit current (J(SC)). For example, the ternary PSC devices of P3HT:(OXCMA:OXCTA) with W(OXCTA) of 0.1 and 0.3 exhibited power-conversion efficiencies (PCEs) of 3.91% and 3.96%, respectively, which were significantly higher than the 3.61% provided by the P3HT:OXCMA device. Interestingly, for W(OXCTA) > 0.7, both V(OC) and PCE of the ternary-blend PSCs exhibited nonlinear compositional dependence on W(OXCTA). We noted that the nonlinear compositional trend of P3HT:(OXCMA:OXCTA) was significantly different from that of P3HT:(OXCMA:o-xylenyl C60 bis-adduct (OXCBA)) ternary-blend PSC devices. The fundamental reasons for the differences between the photovoltaic trends of the two different ternary-blend systems were investigated systemically by comparing their optical, electrical, and morphological properties. PMID:23574307

Kang, Hyunbum; Kim, Ki-Hyun; Kang, Tae Eui; Cho, Chul-Hee; Park, Sunhee; Yoon, Sung Cheol; Kim, Bumjoon J

2013-05-22

428

Small-angle X-ray scattering study of the structure of powder fullerene C{sub 60} and fullerene soot  

SciTech Connect

Powder samples of fullerene C{sub 60} and fullerene soot have been studied by the small-angle X-ray scattering method. The radii of gyration of scattering elements have been determined by constructing small-angle diffraction patterns in Guinier coordinates. The data obtained agree well with the results of wide-angle X-ray scattering study, the available data on the structure of the powder fullerene C{sub 60} prepared by the Huffman-Kraetschmer technique, and the structure of the C{sub 60} molecules. Conglomerates of two C{sub 60} molecules, along with crystallites {approx}20 nm in size that are distributed in an amorphous matrix, are present in fullerene powders. Fullerene soot contains C{sub 60} crystallites 20-25 nm in size and graphite crystallites {approx}2-3 nm in size that are distributed in an amorphous matrix.

Ginzburg, B. M. [Russian Academy of Sciences, Institute of Problems of Mechanical Engineering (Russian Federation)], E-mail: ginzburg@tribol.ipme.ru; Tuichiev, Sh.; Tabarov, S. Kh. [Tajik State University (Tajikistan); Shepelevskii, A. A. [Russian Academy of Sciences, Institute of Problems of Mechanical Engineering (Russian Federation)

2007-03-15

429

Effect of Boron doping on the electronic properties of the fullerenes of different sizes  

SciTech Connect

We report the results of the effect of Boron doping in C{sub n}; n = 28, 32, 36, 40, 44, 50 and 60 using the first principle calculation based on density functional theory. The HOMO-LUMO gap changes significantly with the decreasing fullerene size below C{sub 60}, with maximum gap observed for C{sub 32}. The HOMO-LUMO gap of Boron doped fullerenes varies significantly w.r.t. pure fullerenes. Also, the gap decreases for C{sub n-m}B{sub m}X, the boron doped fullerenes with exohedral alkali metals for n = 28, 32, 36, 40, 44, 50 and 60; m = 1 to 4; X = Li, Na and K. The Mulliken charge transfer from the exohedral alkali metals towards the various fullerene cages is altered marginally by the boron doping in fullerenes and follows the order K>Na>Li.

Agnihotri, Deepak [Department of Applied Sciences, Rayat and Bahra Institute of Engg. and Biotechnology, Sahauran, Mohali, Punjab 140104 (India); Sharma, Hitesh [Department of Physics, Punjab Technical University, Jalandhar, Punjab 144601 (India)

2011-12-12

430

In situ observations of fullerene fusion and ejection in carbon nanotubes  

NASA Astrophysics Data System (ADS)

We present insitu experimental observations of fullerenes seamlessly fusing to single-walled carbon nanotubes. The morphing-entry of a fullerene to the interior of a nanotube is also captured. The confined (1D) motion of the newly-encapsulated fullerene within its host attests to the actual change from the exterior to interior.We present insitu experimental observations of fullerenes seamlessly fusing to single-walled carbon nanotubes. The morphing-entry of a fullerene to the interior of a nanotube is also captured. The confined (1D) motion of the newly-encapsulated fullerene within its host attests to the actual change from the exterior to interior. Electronic supplementary information (ESI) available: Experimental details and videos. See DOI: 10.1039/c0nr00426j

Gorantla, Sandeep; Börrnert, Felix; Bachmatiuk, Alicja; Dimitrakopoulou, Maria; Schönfelder, Ronny; Schäffel, Franziska; Thomas, Jürgen; Gemming, Thomas; Borowiak-Palen, Ewa; Warner, Jamie H.; Yakobson, Boris I.; Eckert, Jürgen; Büchner, Bernd; Rümmeli, Mark H.

2010-10-01

431

Observation of fullerenes (C60-C70) associated with LDEF crater number 31  

NASA Technical Reports Server (NTRS)

The presence of fullerenes in and around the LDEF crater number 31 is reported. This crater has a high C level associated with it, and is interpreted as having been produced by the impact of a C-rich micrometeoroid. Fullerenes are large 3-D C structures, among which the species C sub 60 (MW 720) and C sub 70 (MW 840) are preeminent. Fullerenes have several UV absorption bands, hence fullerenes should be detectable using UV laser ionization time-of-flight mass spectrometry. We use a LIMA-2A instrument with pulsed UV laser (266 nm) to search for high mass C species associated with LDEF crater number 31. The mass range was 0 to 1200 amu. Low ablating laser power levels were used (less than or = 5 x 10 exp 7 W/sq. cm); 200 mass spectra were acquired and summed. We observed high mass signals near m/z 720, exhibiting 24 amu separation, which is characteristic of fullerenes. Alkali ion signals were also observed. Little or no C clusters of intermediate mass were observed. We interpret the signals around m/z 720 as fullerenes, mainly C sub 60+ with lower levels of C sub 70+. We propose that the mechanism that produces these signals is resonant multiphoton ionization (REMPI). This selective mechanism explains why low mass C cluster ions are not observed along with the fullerenes, since they have much higher ionization potentials. This finding is unexpected, since up to now the search for fullerenes in extraterrestrial materials has not been successful. We conclude that the fullerenes became associated with crater number 31 in space. Two alternative (and exciting) scenarios are being considered at this time: either the fullerenes were carried by the C-rich projectile that formed crater number 31, or the fullerenes formed upon impact with the LDEF. We show the results of experiments at the ARC Vertical Gun Facility, which may establish some constraints on the origin of the fullerenes.

Radicatidibrozolo, Filippo; Fleming, R. H.; Bunch, T. E.

1992-01-01

432

Spherical Bilayer Vesicles of Fullerene-Based Surfactants in Water: A Laser Light Scattering Study  

Microsoft Academic Search

The low solubility of fullerenes in aqueous solution limits their applications in biology. By appropriate substitution, the fullerenes can be transformed into stabilized anions that are water soluble and can form large aggregated structures. A laser light scattering study of the association behavior of the potassium salt of pentaphenyl fullerene (Ph5C60K) in water revealed that the hydrocarbon anions Ph5C60- associate

Shuiqin Zhou; Christian Burger; Benjamin Chu; Masaya Sawamura; Noriaki Nagahama; Motoki Toganoh; Ulrich E. Hackler; Hiroyuki Isobe; Eiichi Nakamura

2001-01-01

433

Modeling Charge Transfer in Fullerene Collisions via Real-Time Electron Dynamics  

SciTech Connect

An approach for performing real-time dynamics of electron transfer in a prototype redox reaction that occurs in reactive collisions between neutral and ionic fullerenes is discussed. The quantum dynamical simulations show that the electron transfer occurs within 60 fs directly preceding the collision of the fullerenes, followed by structural changes and relaxation of electron charge. The consequences of real-time electron dynamics are fully elucidated for the far from equilibrium processes of collisions between neutral and multiply charged fullerenes.

Jakowski, Jacek [ORNL; Irle, Stephan [ORNL; Morokuma, Keiji [ORNL; Sumpter, Bobby G [ORNL

2012-01-01

434

NMR characterization of isomers of C78, C82 and C84 fullerenes  

Microsoft Academic Search

FOLLOWING the development of a method for bulk synthesis of C60 and other fullerenes1, the isolation of higher fullerenes ranging from C76 to C96 has been achieved using chromatographic techniques2-5. Whereas C60 and C70 have unique, high-symmetry structures6, theoretical calculations for fullerenes larger than C76 have suggested that each may exist in at least two isomeric forms7. For C84, 24

Koichi Kikuchi; Nobuo Nakahara; Tomonari Wakabayashi; Shinzo Suzuki; Haruo Shiromaru; Yoko Miyake; Kazuya Saito; Isao Ikemoto; Masatsune Kainosho; Yohji Achiba

1992-01-01

435

Separation of Fullerenes C60, C70, and C76-84 on Polystyrene Divinylbenzene Columns  

Microsoft Academic Search

New HPLC methods have been developed to effectively separate and recover essentially pure amounts of C60 and C70 fullerenes from the lower MW contaminants and higher MW fullerenes co-extracted from carbon soot. Separation with toluene\\/methylene chloride mobile phase results from different degrees of interaction of conjugated ?-electrons of the fullerenes and the polystyrene divinylbenzene (PSDVB) resin stationary phase. The presence

D. L. Stalling; K. C. Kuo; C. Y. Guo; S. Saim

1993-01-01

436

Comparison of the photosensitivity and bacterial toxicity of spherical and tubular fullerenes of variable aggregate size  

Microsoft Academic Search

Nanomaterials such as fullerene C60, carbon nanotubes (CNTs), and other fullerenes show unique electrical, chemical, mechanical, and thermal properties that\\u000a are not well understood in the context of the environmental behavior of this class of carbon-based materials. In this study,\\u000a aqueous suspensions of three fullerenes nanoparticles, C60, single-wall (SW) and multi-wall (MW) CNTs were prepared by sonication and tested for

So-Ryong Chae; Mathieu Therezien; Jeffrey Farner Budarz; Lauren Wessel; Shihong Lin; Yao Xiao; Mark R. Wiesner

437

Colloidal structure and stabilization mechanism of aqueous solutions of unmodified fullerene C{sub 60}  

SciTech Connect

Despite the inability of fullerenes to be directly dissolved in water, there are methods for preparing stable dispersions of fullerenes in water without any particular modifications of the fullerene or addition of stabilizers. The colloidal properties of such systems prepared by replacing the solvent and structural changes in them during coagulation have been studied. The coagulation dynamics has been investigated by spectroscopy and small-angle neutron scattering. The results obtained confirm the colloidal nature of such systems. During coagulation, particles retain a large volume of water around them, an indication of interaction between fullerene and water during solution stabilization.

Khokhryakov, A. A., E-mail: art@nf.jinr.ru; Kyzyma, O. A. [Joint Institute for Nuclear Research (Russian Federation); Bulavin, L. A. [Shevchenko National University (Ukraine); Len, A. [Research Institute for Solid-State Physics and Optics (Hungary); Avdeev, M. V.; Aksenov, V. L. [Joint Institute for Nuclear Research (Russian Federation)

2007-05-15

438

Ultrafast processes of photoinduced charge and energy transfer in nanostructural fullerene-metal films  

SciTech Connect

The primary stages of photoinduced processes in tin-doped C{sub 60} fullerene films have been studied using a femtosecond pump-probe technique with 150-fs laser excitation pulses ({lambda} = 400 nm) and differential transmission and reflection probing in the 1100-1700 nm range. The relaxation dynamics strongly depends both on the metal-to-fullerene ratio in the film and on the mutual distribution (packing) of components in the nanocomposite material. The observed response signal dynamics is related to features in the charge carrier generation, energy transfer between fullerene molecules, and charge transport between metal and fullerene.

Chekalin, S. V. [Russian Academy of Sciences, Institute of Spectroscopy (Russian Federation)], E-mail: chekalin@isan.troitsk.ru

2006-11-15

439

Synthesis of Fullerenes in Low Pressure Benzene/Oxygen Diffusion Flames  

NASA Technical Reports Server (NTRS)

The interest in fullerenes is strongly increasing since their discovery by Kroto et al. in 1985 as products of the evaporation of carbon into inert gas at low pressure. Due to their all carbon closed-shell structure, fullerenes have many exceptional physical and chemical properties and a large potential for applications such as superconductors, sensors, catalysts, optical and electronic devices, polymers, high energy fuels, and biological and medical materials. This list is still growing, because the research on fullerenes is still at an early stage. Fullerenes can be formed not only in a system containing only carbon and an inert gas, but also in premixed hydrocarbon flames under reduced pressure and fuel rich conditions. The highest yields of fullerenes in flames are obtained under conditions of substantial soot formation. There is a need for more information on the yields of fullerenes under different conditions in order to understand the mechanisms of their formation and to enable the design of practical combustion systems for large-scale fullerene production. Little work has been reported on the formation of fullerenes in diffusion flames. In order to explore the yields of fullerenes and the effect of low pressure in diffusion flames, therefore we constructed and used a low pressure diffusion flame burner in this study.

Hebgen, Peter; Howard, Jack B.

1999-01-01

440

The antioxidative effect of fullerenes during the peroxidation of methyl linoleate in toluene.  

PubMed

The antioxidative effect of fullerenes C(60) and C(70) was examined by measuring the inhibition of methyl linoleate (MeL) peroxidation in toluene initiated by 2,2'-azobis(2,4-dimethylvaleronitrile) (AMVN). The fullerenes retarded the formation of MeL hydroperoxides and lowered the rate of propagation. The reaction rates of fullerenes with AMVN-derived peroxyl radicals were much higher than that of MeL. These results indicate that fullerenes can act as retarders of lipid peroxidation, though their activity is low compared with that of ?-tocopherol. PMID:22232272

Kadowaki, Akio; Iwamoto, Satoshi; Yamauchi, Ryo

2012-01-01

441

Spectroscopy of Fullerenes, Fulleranes and PAHs in the UV, Visible and Near Infrared Spectral Range  

NASA Astrophysics Data System (ADS)

The spectra of fullerenes C60 and C70, higher fullerenes C76, C78 and C84 and hydrogenated fullerenes (fulleranes) were studied in laboratory in the UV and in the visible spectral range and could be used for searching and recognizing these molecules in space. Furthermore, the radical cation spectra of all the mentioned fullerene series and also of a series of large and very large polycyclic aromatic hydrocarbons (PAHs) were generated in the laboratory and studied in the near infrared spectral range.

Cataldo, F.; García-Hernández, D. A.; Manchado, A.; Iglesias-Groth, S.

2014-02-01

442

Tuning the interactions between electron spins in fullerene-based triad systems.  

PubMed

A series of six fullerene-linker-fullerene triads have been prepared by the stepwise addition of the fullerene cages to bridging moieties thus allowing the systematic variation of fullerene cage (C60 or C70) and linker (oxalate, acetate or terephthalate) and enabling precise control over the inter-fullerene separation. The fullerene triads exhibit good solubility in common organic solvents, have linear geometries and are diastereomerically pure. Cyclic voltammetric measurements demonstrate the excellent electron accepting capacity of all triads, with up to 6 electrons taken up per molecule in the potential range between -2.3 and 0.2 V (vs Fc(+)/Fc). No significant electronic interactions between fullerene cages are observed in the ground state indicating that the individual properties of each C60 or C70 cage are retained within the triads. The electron-electron interactions in the electrochemically generated dianions of these triads, with one electron per fullerene cage were studied by EPR spectroscopy. The nature of electron-electron coupling observed at 77 K can be described as an equilibrium between doublet and triplet state biradicals which depends on the inter-fullerene spacing. The shorter oxalate-bridged triads exhibit stronger spin-spin coupling with triplet character, while in the longer terephthalate-bridged triads the intramolecular spin-spin coupling is significantly reduced. PMID:24605154

Lebedeva, Maria A; Chamberlain, Thomas W; Davies, E Stephen; Thomas, Bradley E; Schröder, Martin; Khlobystov, Andrei N

2014-01-01

443

Nonlinear optical properties of solutions of heavy fullerenes in the near-ultraviolet region  

NASA Astrophysics Data System (ADS)

Nonlinear optical properties (particularly optical limiting) are determined for solutions of heavy fullerenes C76 + C78 + C84 + C90 + …, in the near-ultraviolet region (? ? 280 ± 7 nm). It is shown that no optical limiting is observed in solutions of light fullerenes (C60 and C70), but found in solutions of water-soluble fullerenol-d (a mixture of oxypolyalcohols of fullerene C60-C60(OH) n1O n2, with their sodium salts) based on light fullerenes.

Sherstnev, V. V.; Charykov, N. A.; Semenov, K. N.; Alekseev, N. I.; Keskinov, V. A.; Krokhina, O. A.

2011-09-01

444

Spectroscopy of fullerenes, fulleranes and PAHs in the UV, visible and near infrared spectral range  

E-print Network

The spectra of fullerenes C60 and C70, higher fullerenes C76, C78 and C84 and hydrogenated fullerenes (fulleranes) were studied in laboratory in the UV and in the visible spectral range and could be used for searching and recognizing these molecules in space. Furthermore, the radical cation spectra of all the mentioned fullerene series and also of a series of large and very large polycyclic aromatic hydrocarbons (PAHs) were generated in laboratory and studied in the near infrared spectral range.

Cataldo, F; Manchado, A; Iglesias-Groth, S

2013-01-01

445

Time resolved spectroscopy and gain studies of Fullerenes C60 and C70.  

PubMed

The fluorescence decay time of Fullerenes C60 and C70 in pure form as well as in mixture with Coumarin C440 and Quinizarine dyes are studied. Results indicate that the decay of pure fullerenes is constant throughout the solute concentration and it is also independent of excitation wavelength, whereas in the case of mixture with dyes different behavior is noticed. We have also calculated the Stern-Volmer quenching constant and optical gain of both the fullerenes from which it is found that the optical gain is positive for Fullerene C70 only in a very narrow range of concentration. PMID:23747380

Qaiser, Darakhshan; Khan, Mohd Shahid; Singh, R D; Khan, Zahid H

2013-09-01

446

Effect of Self-Assembly of Fullerene Nano-Particles on Lipid Membrane  

PubMed Central

Carbon nanoparticles can penetrate the cell membrane and cause cytotoxicity. The diffusion feature and translocation free energy of fullerene through lipid membranes is well reported. However, the knowledge on self-assembly of fullerenes and resulting effects on lipid membrane is poorly addressed. In this work, the self-assembly of fullerene nanoparticles and the resulting influence on the dioleoylphosphtidylcholine (DOPC) model membrane were studied by using all-atom molecular dynamics simulations with explicit solvents. Our simulation results confirm that gathered small fullerene cluster can invade lipid membrane. Simulations show two pathways: 1) assembly process is completely finished before penetration; 2) assembly process coincides with penetration. Simulation results also demonstrate that in the membrane interior, fullerene clusters tend to stay at the position which is 1.0 nm away from the membrane center. In addition, the diverse microscopic stacking mode (i.e., equilateral triangle, tetrahedral pentahedral, trigonal bipyramid and octahedron) of these small fullerene clusters are well characterized. Thus our simulations provide a detailed high-resolution characterization of the microscopic structures of the small fullerene clusters. Further, we found the gathered small fullerene clusters have significant adverse disturbances to the local structure of the membrane, but no great influence on the global integrity of the lipid membrane, which suggests the prerequisite of high-content fullerene for cytotoxicity. PMID:24204827

Zhang, Saiqun; Mu, Yuguang; Zhang, John Z. H.; Xu, Weixin

2013-01-01

447

Immobilization of [60]fullerene on silicon surfaces through a calix[8]arene layer  

SciTech Connect

In this work, we report the functionalization of flat Si(100) surfaces with a calix[8]arene derivative through a thermal hydrosilylation process, followed by docking with [60]fullerene. Chemical grafting of calix[8]arene on silicon substrates was evaluated by X-ray photoelectron spectroscopy, whereas host-guest immobilization of fullerene was demonstrated by atomic force microscopy and sessile drop water contact angle measurements. Surface topographical variations, modelled on the basis of calix[8]arene and [60]fullerene geometrical parameters, are consistent with the observed morphological features relative to surface functionalization and to non-covalent immobilization of [60]fullerene.

Busolo, Filippo; Silvestrini, Simone; Maggini, Michele [Department of Chemical Sciences, ITM-CNR University of Padova, Via F. Marzolo 1, 35131 Padova (Italy)] [Department of Chemical Sciences, ITM-CNR University of Padova, Via F. Marzolo 1, 35131 Padova (Italy); Armelao, Lidia [Department of Chemical Sciences, IENI-CNR and INSTM, University of Padova, Via F. Marzolo 1, 35131 Padova (Italy)] [Department of Chemical Sciences, IENI-CNR and INSTM, University of Padova, Via F. Marzolo 1, 35131 Padova (Italy)

2013-10-28

448

Effect of nitrogen atomic percentage on N+-bombarded MWCNTs in cytocompatibility and hemocompatibility  

PubMed Central

N+-bombarded multi-walled carbon nanotubes (N+-bombarded MWCNTs), with different nitrogen atomic percentages, were achieved by different N ion beam currents using ion beam-assisted deposition (IBAD) on MWCNTs synthesized by chemical vapor deposition (CVD). Characterizations of N+-bombarded MWCNTs were evaluated by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), Raman spectroscopy, and contact angle. For comparison, the in vitro cytocompatibility of the N+-bombarded MWCNTs with different N atomic percentages was assessed by cellular adhesion investigation using human endothelial cells (EAHY926) and mouse fibroblast cells (L929), respectively. The results showed that the presence of nitrogen in MWCNTs accelerated cell growth and proliferation of cell culture. The higher nitrogen content of N+-bombarded MWCNTs, the better cytocompatibility. In addition, N+-bombarded MWCNTs with higher N atomic percentage displayed lower platelet adhesion rate. No hemolysis can be observed on the surfaces. These results proved that higher N atomic percentage led N+-bombarded MWCNTs to better hemocompatibility. PMID:24666845

2014-01-01

449

Erosion of frozen sulfur dioxide by ion bombardment - Applications to Io  

NASA Technical Reports Server (NTRS)

The erosion of frozen SO2 due to bombardment by both light and heavy ions (He and F) was measured for bombarding energies of 0.08 to 1.3 MeV/amu. The number of SO2 molecules ejected from the target per incident ion (i.e., the sputtering yield) was 50 for 1.5 MeV He ions and 7300 for 6 MeV F ions. Ion bombardment followed by heating produced an oxygen/sulfur residue which was much more stable against subsequent ion bombardment than the initial frozen SO2. The erosion rate of SO2 frost on Jupiter's moon Io depends strongly on the elemental composition and energy spectra of the magnetospheric ion flux which bombards the surface. The combined effects of ion bombardment and heating which produced residues on the target substrates may also occur on Io from magnetospheric ion bombardment and heating by volcanism. The experimental results compare favorably with a new model of the sputtering process which considers the energy loss of the incident ion to electronic excitation in the target.

Melcher, C. L.; Lepoire, D. J.; Cooper, B. H.; Tombrello, T. A.

1982-01-01

450

Effect of nitrogen atomic percentage on N+-bombarded MWCNTs in cytocompatibility and hemocompatibility  

NASA Astrophysics Data System (ADS)

N+-bombarded multi-walled carbon nanotubes (N+-bombarded MWCNTs), with different nitrogen atomic percentages, were achieved by different N ion beam currents using ion beam-assisted deposition (IBAD) on MWCNTs synthesized by chemical vapor deposition (CVD). Characterizations of N+-bombarded MWCNTs were evaluated by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), Raman spectroscopy, and contact angle. For comparison, the in vitro cytocompatibility of the N+-bombarded MWCNTs with different N atomic percentages was assessed by cellular adhesion investigation using human endothelial cells (EAHY926) and mouse fibroblast cells (L929), respectively. The results showed that the presence of nitrogen in MWCNTs accelerated cell growth and proliferation of cell culture. The higher nitrogen content of N+-bombarded MWCNTs, the better cytocompatibility. In addition, N+-bombarded MWCNTs with higher N atomic percentage displayed lower platelet adhesion rate. No hemolysis can be observed on the surfaces. These results proved that higher N atomic percentage led N+-bombarded MWCNTs to better hemocompatibility.

Zhao, Mengli; Cao, Ye; Liu, Xiaoqi; Deng, Jianhua; Li, Dejun; Gu, Hanqing

2014-03-01

451

Influence of Substrate on Crystallization in Polythiophene/fullerene Blends  

SciTech Connect

The nanoscale morphology of the active layer in organic, bulk heterojunction (BHJ) solar cells is crucial to device performance. Often a combination of casting conditions and post deposition thermal treatment is used to optimize the morphology. In general, the development of microscopic crystals is deleterious, as the exciton diffusion length is {approx}10 nm. We find that the microscopic crystallization behavior in polythiophene/fullerene blends is strongly influenced by the substrate on which the BHJ is cast. With a silicon oxide substrate, the crystal nucleation density is high and significant crystallization occurs at a temperature of 140 C. On more hydrophobic substrates, significantly higher temperatures are required for observable crystallization. This difference is attributed to the interfacial segregation of the PCBM, controlled by the substrate surface energy. The substrate dependence of crystallization has significant implications on the fullerene crystal growth mechanisms and practical implications for device studies.

C He; D Germack; J Kline; D Delongchamp; D Fischer; C Snyder; M Toney; J Kushmerick; L Richter

2011-12-31

452

Photoabsorption spectrum of the Xe@C$_{60}$ endohedral fullerene  

E-print Network

Photoabsorption spectrum of the Xe@C$_{60}$ endohedral fullerene has been studied using the time-dependent-density-functional-theory (TDDFT), which represents the dynamical polarizability of an interacting electron system by an off-diagonal matrix element of the resolvent of the Liouvilliam superoperator and solves the problem with the Lanczos algorithm. The method has been tested with the photoabsorption cross sections of the free Xe atom and C$_{60}$ fullerene. The result for the Xe@C$_{60}$ confirms the three main peaks observed in the recent measurement in the energy region of the Xe 4$d$ giant resonance and demonstrates the underestimation of the photoionization cross section by the experiment. It is suggested to use the current theoretical result around 22 eV to calibrate the experimental data.

Chen, Zhifan

2012-01-01

453

Characterization of C60 fullerene complexation with antibiotic doxorubicin.  

PubMed

The aim of this paper was to provide the physico-chemical characterization of a key process leading to amplification of the antitumor effect of antibiotic Doxorubicin (Dox) in vivo and in vitro and occurring at the molecular level through complexation with C60 fullerene. A wide range of physico-chemical tools was used such as UV/Vis and NMR spectroscopies, atomic force microscopy, isothermal titration calorimetry and zeta-potential methods. The unusual thermodynamic behavior of the complexation process was reported, featuring unexpected and, to a certain extent, contradictory experimental observations. The explanation of the obtained results was proposed resulting in creation of a general view on aromatic drug binding with C60 fullerene. Based on these results some important practical outcomes for anticancer therapy were formulated. PMID:25251969

Prylutskyy, Yu I; Evstigneev, M P; Pashkova, I S; Wyrzykowski, D; Woziwodzka, A; Go?u?ski, G; Piosik, J; Cherepanov, V V; Ritter, U

2014-10-01

454

Recombination in polymer-fullerene bulk heterojunction solar cells  

SciTech Connect

Recombination of photogenerated charge carriers in polymer bulk heterojunction (BHJ) solar cells reduces the short circuit current (J{sub sc} ) and the fill factor (FF). Identifying the mechanism of recombination is, therefore, fundamentally important for increasing the power conversion efficiency. Light intensity and temperature-dependent current-voltage measurements on polymer BHJ cells made from a variety of different semiconducting polymers and fullerenes show that the recombination kinetics are voltage dependent and evolve from first-order recombination at short circuit to bimolecular recombination at open circuit as a result of increasing the voltage-dependent charge carrier density in the cell. The “missing 0.3 V” inferred from comparison of the band gaps of the bulk heterojunction materials and the measured open-circuit voltage at room-temperature results from the temperature dependence of the quasi-Fermi levels in the polymer and fullerene domains—a conclusion based on the fundamental statistics of fermions.

Cowan, Sarah; Roy, Anshuman; Heeger, Alan

2010-01-01

455

Optical properties of fullerenes confined in ordered alumina nanotube arrays  

NASA Astrophysics Data System (ADS)

In the present work, oxalic amorphous porous anodic alumina membranes (AAM) with highly ordered porous arrays and average nanometric porous dimensions of 70 nm in diameter and 37 microns in depth (nanotubes) were prepared and successfully used as hosting matrix for C60 and C70 fullerene compounds. Atomic force microscopy (AFM) studies were performed on the hybrid samples in order to explore surface morphology and optimal insertion of these molecular systems into the AAM environment. The cubic nonlinear optical (NLO) properties, such as nonlinear refraction and absorption of the hybrid samples were studied via the Z-Scan technique in order to evaluate their NLO-performance. Hybrid AAM with fullerene compounds have shown outstanding NLO-activity with positive NLO-refractive coefficients.

Ontiveros-Barrera, F. G.; Morales-Saavedra, O. G.; Mata-Zamora, M. E.; Bañuelos, J. G.; Rodríguez-Rosales, A. A.; Álvarez-Zauco, E.

2011-09-01

456

Stability of multiply charged fullerene anions and cations  

NASA Astrophysics Data System (ADS)

We present a systematic study of the stability of highly charged cationic and anionic fullerenes whose most stable neutral counterparts follow the isolated pentagon rule (IPR). In agreement with recent studies, we have found that, for many highly charged fullerenes, non-IPR isomers are significantly more stable than the IPR ones. To understand this behavior, we compare the results of elaborate density-functional theory (DFT) calculations to those of a simple Hückel molecular-orbital theory in which the DFT energies of the corresponding neutral systems are used as a reference. The model leads to a reasonable estimate of the relative stability of the IPR and non-IPR isomers as a function of charge, which can be used to identify, among the thousands of possible isomers and charge states, the non-IPR species that are likely more stable than the IPR isomers.

Wang, Yang; Zettergren, Henning; Alcamí, Manuel; Martín, Fernando

2009-09-01

457

Fullerene peapods: In-situ conductivity study during synthesis  

NASA Astrophysics Data System (ADS)

We report in-situ measurement of the conductivity during the synthesis of C60-filled single-walled carbon nanotubes (SWNTs), so-called fullerene peapods. The synthesis was performed in a sealed quartz tube at 773 K by using the sublimation of C60 into the hollow space of the SWNTs. The change in the resistance in the SWNT buckypaper was monitored during the C60-filling process, and the temperature dependence of the resistance was compared to that for empty SWNTs and fullerene peapods. The SWNT networks became more metallic due to the encapsulation of C60, and a reduced temperature dependence of the resistivity was observed in the peapods, with an overall decrease in the resistivity. The interaction between the SWNT and C60 molecules, changing the electronic properties of SWNTs, can provide a way to functionalize the SWNTs.

You, Young Gyu; Kim, Sung Won; Uhm, Tae Woo; Jhang, Sung Ho; Park, Yung Woo

2014-06-01

458

Selecting boron fullerenes by cage-doping mechanisms.  

PubMed

So far, no boron fullerenes were synthesized: more compact sp(3)-bonded clusters are energetically preferred. To circumvent this, metallic clusters have been suggested by Pochet et al. [Phys. Rev. B 83, 081403(R) (2011)] as "seeds" for a possible synthesis which would topologically protect the sp(2) sector of the configuration space. In this paper, we identify a basic pentagonal unit which allows a balance between the release of strain and the self-doping rule. We formulate a guiding principle for the stability of boron fullerenes, which takes the form of an isolated filled pentagon rule (IFPR). The role of metallic clusters is then reexamined. It is shown that the interplay of the IFPR and the seed-induced doping breaks polymorphism and its related problems: it can effectively select between different isomers and reduce the reactivity of the boron shells. The balance between self and exterior doping represents the best strategy for boron buckyball synthesis. PMID:23676039

Boulanger, Paul; Morinière, Maxime; Genovese, Luigi; Pochet, Pascal

2013-05-14

459

Exciton dynamics in alternating polyfluorene/fullerene blends  

NASA Astrophysics Data System (ADS)

Exciton dynamics in alternating copolymer/fullerene solar cell blends have been investigated using femtosecond transient absorption spectroscopy. The acceptor concentrations have been varied over a wide range. Experimental data, kinetic modeling and simulations, all indicate that the efficiency of exciton conversion to charges is 100% even at acceptor concentrations as low as 20 wt%. The reported dependence of solar cell efficiency on fullerene concentration may thus arise from other factors. However, there exists an acceptor concentration threshold (5 wt%) below which a substantial fraction of the excitations remain unquenched. The results, we believe are very relevant to optimization of performance efficiency by clever manipulation of morphology. We have also observed exciton-exciton energy transfer in these blends at low acceptor concentrations.

De, Swati; Kesti, Tero; Maiti, Manisankar; Zhang, Fengling; Inganäs, Olle; Yartsev, Arkady; Pascher, Torbjörn; Sundström, Villy

2008-06-01

460

Compositional Evolution of Saturn's Rings Due to Meteoroid Bombardment  

NASA Technical Reports Server (NTRS)

In this paper we address the question of compositional evolution in planetary ring systems subsequent to meteoroid bombardment. The huge surface area to mass ratio of planetary rings ensures that this is an important process, even with current uncertainties on the meteoroid flux. We develop a new model which includes both direct deposition of extrinsic meteoritic "pollutants", and ballistic transport of the increasingly polluted ring material as impact ejecta. Our study includes detailed radiative transfer modeling of ring particle spectral reflectivities based on refractive indices of realistic constituents. Voyager data have shown that the lower optical depth regions in Saturn's rings (the C ring and Cassini Division) have darker and less red particles than the optically thicken A and B rings. These coupled structural-compositional groupings have never been explained; we present and explore the hypothesis that global scale color and compositional differences in the main rings of Saturn arise naturally from extrinsic meteoroid bombardment of a ring system which was initially composed primarily, but not entirely, of water ice. We find that the regional color and albedo differences can be understood if all ring material was initially identical (primarily water ice, based on other data, but colored by tiny amounts of intrinsic reddish, plausibly organic, absorber) and then evolved entirely by addition and mixing of extrinsic, nearly neutrally colored. plausibly carbonaceous material. We further demonstrate that the detailed radial profile of color across the abrupt B ring - C ring boundary can.constrain key unknown parameters in the model. Using new alternates of parameter values, we estimate the duration of the exposure to extrinsic meteoroid flux of this part of the rings, at least, to be on the order of 10(exp 8) years. This conclusion is easily extended by inference to the Cassini Division and its surroundings as well. This geologically young "age" is compatible with timescales estimated elsewhere based on the evolution of ring structure due to ballistic transport, and also with other "short timescales" estimated on the grounds of gravitational torques. However, uncertainty in the flux of interplanetary debris and in the ejects yield may preclude ruling out a ring age as old as the solar system at this time.

Cuzzi, J.; Estrada, P.; Young, Richard E. (Technical Monitor)

1997-01-01

461

Implications of the 17 keV neutrino  

SciTech Connect

Constraints on the theoretical interpretation of the 17 keV neutrino are reviewed. A simple understanding of the 17 keV neutrino is provided by flavon models, which involve the spontaneous breaking of Abelian lepton symmetries and have only the usual three light neutrino species. Signatures for this class of models include neutrino oscillations, tau decay to an electron and a flavon, and invisible decay modes of the Higgs boson to two flavons.

Hall, L.J.

1991-06-01

462

Effect of proton bombardment on InAs dots and wetting layer in laser structures  

SciTech Connect

The effect of proton bombardment on carrier lifetime and photoluminescence of InAs quantum dots was measured. Optical absorption and transmission electron microscopy show the dots retain their integrity under bombardment. A decrease in ground state photoluminescence with increasing dose is not explained by the decrease in dot carrier lifetime alone, but also by bombardment-induced non-radiative recombination in the wetting layer, which reduces the dot electron population at fixed excitation. To exploit the relative radiation immunity of quantum dots, it is necessary to maximise the dot density and capture probability per dot to minimize the effect of wetting layer recombination.

O'Driscoll, I.; Blood, P.; Smowton, P. M.; Sobiesierski, A. [School of Physics and Astronomy, Cardiff University, Queens Buildings, The Parade, Cardiff CF24 3AA (United Kingdom); Gwilliam, R. [Advanced Technology Institute, FEPS, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom)

2012-06-25

463

Changes in a surface of polycrystalline aluminum upon bombardment with argon ions  

NASA Astrophysics Data System (ADS)

The interaction between argon ions and a natural oxide layer of polycrystalline aluminum is studied via Auger electron (AE) and electron energy loss (EEL) spectroscopy. It is found that bombardment with argon ions whose energy is lower than the Al2O3 sputtering threshold results in the accumulation of bombarding ions in interstitial surface voids, thus forming a supersaturated solid solution of target atoms and bombarding ions of argon and nitrogen entrapped by the ion beam from the residual gas of the working chamber of the spectrometer.

Ashkhotov, O. G.; Ashkhotova, I. B.; Bliev, A. P.; Magkoev, T. T.; Krymshokalova, D. A.

2014-10-01

464

Influence of helium-ion bombardment on the surface properties of pure and ammonia-adsorbed water thin films  

NASA Astrophysics Data System (ADS)

The influence of the ion bombardment on the surface properties of water-ice films has been investigated. The films are irradiated with 1.5 keV He + ions and analyzed sequentially on the basis of time-of-flight secondary-ion mass spectrometry (TOF-SIMS). In order to minimize any temperature-induced effects, the measurements were made at 15 K. The damage of the films, as estimated from the H/D exchange between NH 3 and the D 2O ice and the intermixing of NH 3 with the H 218O ice, is recognized at the fluence above 2 × 10 14 ions/cm 2. The sputtering yield of the D 2O ice is determined as 0.9 ± 0.2 molecules per incoming He + ion. The temperature-programmed TOF-SIMS analysis of the water-ice films has been completed within the fluence of 5.8 × 10 12 ions/cm 2, so that no appreciable damage of the film should be induced during the measurement.

Kondo, M.; Shibata, T.; Kawanowa, H.; Gotoh, Y.; Souda, R.

2005-05-01

465

Solubility of Fullerenes C60 and C70 in Water  

Microsoft Academic Search

Fullerenes C(sub)60 and C(sub)70, the all-carbon molecules with closed-cage structures, have been found naturally in soot-rich clays and marls at the Cretaceous-Tertiary boundary. All were marine sediments which were permeated by water even after the consolidated rocks had become uplifted above sea level. Because of this, one would like to know the solubilities of C(sub)60 and C(sub)70 in water in

D. Heymann

1996-01-01

466

Structural organization of fullerenes C60, C70, C84  

Microsoft Academic Search

An overview is given of structural organization of fullerene crystals of C60, C70, C84, including the phases taking place at lower temperature when molecules order. Recently, evidences were obtained for a phase transition in C84 and for a metastability of phases in C70 A particular attention is paid to the symmetry properties of phases and to mesoscopic structures due to

P. Saint-gregoire; R. Almairac; E. Snoeck; J. Moret; V. Kopsky

1999-01-01

467

TECHNOLOGIE PLASMA TRIPHASEE POUR LA SYNTHESE DE FULLERENES EN CONTINU  

E-print Network

/He). Le procédé plasma permet la synthèse de deux types de produits: · Des fullerènes, principalement C60 et C70, · De la suie fullerénique qui est une suie présentant notamment une structure fulleréniqueTECHNOLOGIE PLASMA TRIPHASEE POUR LA SYNTHESE DE FULLERENES EN CONTINU F. Fabry1 J. Gonzalez

Paris-Sud XI, Université de

468

Tribological properties of fullerenes C60 and C70 microparticles  

Microsoft Academic Search

The frictional behaviors of fullerenes C60 and C70 were studied because they were speculated to be solid lubricants. For the sublimated pure C60 films on Si(001), a high friction coefficient (0.55–0.8) was observed under different loads and pin materials. For the C70 film, the friction coefficient showed a pin dependence, which changed from 0.5 with an Al2O3 pin to about

Wei Zhao; Jinke Tang; Ashok Puri; Ray L. Sweany; Yuxin Li; Liquan Chen

1996-01-01

469

Nuclear spin circular dichroism in fullerenes: a computational study.  

PubMed

In the recently proposed phenomenon, nuclear spin-induced circular dichroism (NSCD), collective magnetisation of nuclei induces circular dichroism in a light beam passing through a molecular sample. Here we present the first computational predictions of NSCD for fullerenes C60 and C70. We show that the NSCD signal is nucleus-specific, like in NMR spectroscopy. Thus, NSCD may provide a new and promising, high-resolution observable for experimental identification of chemical compounds. PMID:25341745

Straka, Michal; St?pánek, Petr; Coriani, Sonia; Vaara, Juha

2014-11-01

470

Distinct Cytotoxic Mechanisms of Pristine versus Hydroxylated Fullerene  

Microsoft Academic Search

The mechanisms underlying the cytotoxic action of pure ful- lerene suspension (nano-C60) and water-soluble polyhydroxylated fullerene (C60(OH)n) were investigated. Crystal violet assay for cell viability demonstrated that nano-C60 was at least three orders of magnitude more toxic than C60(OH)n to mouse L929 fibrosar- coma, rat C6 glioma, and U251 human glioma cell lines. Flow cytometry analysis of cells stained with

Aleksandra Isakovic; Zoran Markovic; Biljana Todorovic-Markovic; Nadezda Nikolic; Sanja Vranjes-Djuric; Marija Mirkovic; Miroslav Dramicanin; Ljubica Harhaji; Nevena Raicevic; Zoran Nikolic; Vladimir Trajkovic

2006-01-01

471

Is the Use of Fullerene in Photodynamic Therapy Effective for Atherosclerosis?  

SciTech Connect

The purpose of this study was to evaluate Fullerene as a therapeutic photosensitizer in the treatment of atherosclerosis. An atherosclerotic experimental rabbit model was prepared by causing intimal injury to bilateral external iliac arteries using balloon expansion. In four atherosclerotic rabbits and one normal rabbit, polyethylene glycol-modified Fullerene (Fullerene-PEG) was infused into the left external iliac artery and illuminated by light emitting diode (LED), while the right external iliac artery was only illuminated by LED. Two weeks later, the histological findings for each iliac artery were evaluated quantitatively and comparisons were made among atherosclerotic Fullerene+LED artery (n = 4), atherosclerotic light artery (n = 4), normal Fullerene+LED artery (n = 1), and normal light artery (n = 1). An additional two atherosclerotic rabbits were studied by fluorescence microscopy, after Fullerene-PEG-Cy5 complex infusion into the left external iliac artery, for evaluation of Fullerene-PEG incorporated within the atherosclerotic lesions. The degree of atherosclerosis in the atherosclerotic Fullerene+LED artery was significantly (p < 0.05) more severe than that in the atherosclerotic LED artery. No pathological change was observed in normal Fullerene+LED and LED arteries. In addition, strong accumulation of Fullerene-PEG-Cy5 complex within the plaque of the left iliac artery of the two rabbits was demonstrated, in contrast to no accumulation in the right iliac artery. We conclude that infusion of a high concentration of Fullerene-PEG followed by photo-illumination resulted not in a suppression of atherosclerosis but in a progression of atherosclerosis in experimental rabbit models. However, this intervention showed no adverse effects on the normal iliac artery.

Nitta, Norihisa, E-mail: r34nitta@belle.shiga-med.ac.jp; Seko, Ayumi; Sonoda, Akinaga; Ohta, Shinichi; Tanaka, Toyohiko; Takahashi, Masashi; Murata, Kiyoshi [Shiga University of Medical Science, Department of Radiology (Japan); Takemura, Shizuki [Shiga University of Medical Science, Department of Pathology (Japan); Sakamoto, Tsutomu [Koka General Hospital, Department of Radiology (Japan); Tabata, Yasuhiko [Kyoto University, Department of Biomaterials, Field of Tissue Engineering (Japan)

2008-03-15

472

Computational studies on non-covalent interactions of carbon and boron fullerenes with graphene.  

PubMed

First-principles DFT calculations are carried out to study the changes in structures and electronic properties of two-dimensional single-layer graphene in the presence of non-covalent interactions induced by carbon and boron fullerenes (C60, C70, C80 and B80). Our study shows that larger carbon fullerene interacts more strongly than the smaller fullerene, and boron fullerene interacts more strongly than that of its carbon analogue with the same nuclearity. We find that van der Waals interactions play a major role in governing non-covalent interactions between the adsorbed fullerenes and graphene. Moreover, a greater extent of van der Waals interactions found for the larger fullerenes, C80 and B80, relative to smaller C60, and consequently, results in higher stabilisation. We find a small amount of electron transfer from graphene to fullerene, which gives rise to a hole-doped material. We also find changes in the graphene electronic band structures in the presence of these surface-decorated fullerenes. The Dirac cone picture, such as that found in pristine graphene, is significantly modified due to the re-hybridisation of graphene carbon orbitals with fullerenes orbitals near the Fermi energy. However, all of the composites exhibit perfect conducting behaviour. The simulated absorption spectra for all of the graphene-fullerene hybrids do not exhibit a significant change in the absorption peak positions with respect to the pristine graphene absorption spectrum. Additionally, we find that the hole-transfer integral between graphene and C60 is larger than the electron-transfer integrals and the extent of these transfer integrals can be significantly tuned by graphene edge functionalisation with carboxylic acid groups. Our understanding of the non-covalent functionalisation of graphene with various fullerenes would promote experimentalists to explore these systems, for their possible applications in electronic and opto-electronic devices. PMID:23616400

Manna, Arun K; Pati, Swapan K

2013-06-24

473

Fullerene-bisadduct acceptors for polymer solar cells.  

PubMed

Polymer solar cells (PSCs) have drawn great attention in recent years for their simple device structure, light weight, and low-cost fabrication in comparison with inorganic semiconductor solar cells. However, the power-conversion efficiency (PCE) of PSCs needs to be increased for their future application. The key issue for improving the PCE of PSCs is the design and synthesis of high-efficiency conjugated polymer donors and fullerene acceptors for the photovoltaic materials. For the acceptor materials, several fullerene-bisadduct acceptors with high LUMO energy levels have demonstrated excellent photovoltaic performance in PSCs with P3HT as a donor. In this Focus Review, recent progress in high-efficiency fullerene-bisadduct acceptors is discussed, including the bisadduct of PCBM, indene-C60 bisadduct (ICBA), indene-C70 bisadduct (IC70BA), DMPCBA, NCBA, and bisTOQC. The LUMO levels and photovoltaic performance of these bisadduct acceptors with P3HT as a donor are summarized and compared. In addition, the applications of an ICBA acceptor in new device structures and with other conjugated polymer donors than P3HT are also introduced and discussed. PMID:23853151

Li, Yongfang

2013-10-01

474

Study of urological devices coated with fullerene-like nanoparticles  

NASA Astrophysics Data System (ADS)

Insertion of endoscopes and other medical devices into the human body are ubiquitous, especially among aged males. The applied force for the insertion/extraction of the device from the urethra must overcome endoscope-surface-human-tissue interactions. In daily practice a gel is applied on the endoscope surface, in order to facilitate its entry into the urethra, providing also for local anesthesia. In the present work, a new solid-state lubricant has been added to the gel, in order to reduce the metal-urethra interaction and alleviate the potential damage to the epithelial tissue. For that purpose, a urethra model was designed and fabricated, which allowed a quantitative assessment of the applied force for extraction of the endoscope from a soft polymer-based ring. It is shown that the addition of MoS2 nanoparticles with fullerene-like structure (IF-MoS2) and in particular rhenium-doped nanoparticles (Re:IF-MoS2) to Esracain gel applied on the metal-lead reduced the friction substantially. The Re:IF-MoS2 showed better results than the undoped fullerene-like nanoparticles and both performed better than the gel alone. The mechanism of friction reduction is attributed to fullerenes' ability to roll and act as a separator between the active parts of the model.

Goldbart, Ohad; Elianov, Olga; Shumalinsky, Dmitry; Lobik, Leonid; Cytron, Shmuel; Rosentsveig, Rita; Wagner, H. Daniel; Tenne, Reshef

2013-08-01

475

Continuous symmetry of C60 fullerene and its derivatives.  

PubMed

Conventionally, the I(h) symmetry of fullerene C(60) is accepted, which is supported by numerous calculations. However, this conclusion results from the consideration of the molecule electron system, of its odd electrons in particular, in a closed-shell approximation without taking the electron spin into account. Passing to the open-shell approximation has led to both the energy and the symmetry lowering up to C(i). Seemingly contradicting to a high-symmetry pattern of experimental recording, particularly concerning the molecule electronic spectra, the finding is considered in this Article from the continuous symmetry viewpoint. Exploiting continuous symmetry measure and continuous symmetry level approaches, it was shown that formal C(i) symmetry of the molecule is by 99.99% I(h). A similar continuous symmetry analysis of the fullerene monoderivatives gives a reasonable explanation of a large variety of their optical spectra patterns within the framework of the same C(1) formal symmetry exhibiting a strong stability of the C(60) skeleton. TOC color pictures present chemical portrait of C(60) in terms of atomic chemical susceptibility (Sheka, E. Fullerenes: Nanochemistry, Nanomagnetism, Nanomedicine, Nanophotonics; CRC Press: Taylor and Francis Group, Boca Raton, 2011). PMID:21449547

Sheka, E F; Razbirin, B S; Nelson, D K

2011-04-21

476