Dynamics of the Metal Ion in M@C82 (M=La,Y) Metallofullerenes Studied by Temperature Effects in Electron Spin Resonance Spectra

Abstract

ESR spectra of M@C₈₂ (M=La, Y) metallofullerene solutions show the monotonic decrease of the metal ion hyperfine coupling constant between ?70 and +260°C and changes in the lineshape of Y@C₈₂ signals above 80°C, which were attributed to anharmonic metal-to-cage vibrations and to the motion of Y between different chemisorption sites in a C₈₂ cage, respectively.     

New Approach in Synthesis of Carbon Allotropes in Large Quantities

This work proposes a new method for mass production of carbon allotropes synthesis by arc-plasma. In particular, carbon vapor is produced from graphite electrode by introducing a buffer gas into the electrode gap to generate an intense gas outflow and fast evacuation of the produced vapor from the hot plasma zone. Study of the influence of the gas flow dynamics differently supplied to the hot plasma zone during the fullerenes synthesis was studied and the relationships between different gas flow rates, applied power, diameters of used electrodes and fullerenes productivity and yield were established. The new proposed method allows a significant increase of fullerenes productivity.     

Fullerene Production in a Graphite Tubular Reactor

Effects of operational parameters on the production yield of fullerenes have been detailed by many researchers and up to 20% fullerene yields were attained at optimized pressure, current, and electrode gap. Many of the tests were carried out under static helium pressure and no reference was made to helium flow during the arcing process. It is, however, known that helium flow enhances the fullerene yield. In this study, a tubular graphite reactor was placed into a stainless steel chamber and the arc was generated inside the tubular reactor. Fresh helium was fed at one end of the tubular reactor and vacuum was applied to the other end. Changing the helium flow rate affected the residence time of the particles in the reactive zone. Fullerene yields were obtained to be as high as 32%, which is much above the literature stated values.     

He Ion Bombardment of C70 Fullerene: An FT-IR and Raman Study

C₇₀ fullerene films deposited on a silicon substrate have been bombarded with He⁺ ions at 30 keV at room temperature in vacuum. The structural changes undergone by C₇₀ have been followed by both FT-IR and Raman spectroscopy. The results have been compared to the behavior of C₆₀ fullerene and discussed in an astrochemical context. The main conclusion is that C₇₀, contrary to C₆₀, does not form oligomers at low radiation dose but it is directly and gradually degraded to amorphous carbon (carbon black).     

Optical Emission Measurements of Rotational Temperature of C2 Radicals in Fullerene Processing

In this work, the results of optical emission study of C₂ radicals generated in carbon arc plasma are presented. It was found that a rotational temperature of carbon vapor depends significantly on carbon concentration and inert gas pressure. Experimentally obtained rotational temperature of C₂ emission spectra has been fitted with calculated spectra.     

Progress in Fullerene Chemistry: From Exohedral Functionalization to Heterofullerenes

Various types of cycloaddition such as [2+1], [2+3], and Diels-Alder reactions have been investigated for the purpose of exohedral functionalization of [60]fullerene and also in few cases of [70]fullerene. Thermal and photochemical activation have been used and lead to a variety of new fullerene derivatives which may be further functionalizable. In addition, a new approach to aza-heterofullerenes has been developed starting from an exohedrally activated fullerene.     

Separation of Fullerene and Endofullerene Molecules in Inhomogeneous Electric Field

The present study makes use of the neutral molecule motion model in the inhomogeneous static electric fields. We show the possibility of separating molecules with high polarizability and/or a permanent electric dipole moment in these fields. On the simple example of the electric field of the system of charged parallel metallic wires we have estimated the angle dispersion of the endofullerene molecules Gd@C₈₂, La@C₈₂, Sc@C₈₂, and Y@C₈₂ from the known values of the permanent dipole moments.     

Separation of Fullerene and Endofullerene Molecules in Inhomogeneous Electric Field

Abstract

The present study makes use of the neutral molecule motion model in the inhomogeneous static electric fields. We show the possibility of separating molecules with high polarizability and/or a permanent electric dipole moment in these fields. On the simple example of the electric field of the system of charged parallel metallic wires we have estimated the angle dispersion of the endofullerene molecules Gd@C₈₂, La@C₈₂, Sc@C₈₂, and Y@C₈₂ from the known values of the permanent dipole moments.     

Progress in Fullerene Chemistry: From Exohedral Functionalization to Heterofullerenes

Abstract

Various types of cycloaddition such as [2+1], [2+3], and Diels-Alder reactions have been investigated for the purpose of exohedral functionalization of [60]fullerene and also in few cases of [70]fullerene. Thermal and photochemical activation have been used and lead to a variety of new fullerene derivatives which may be further functionalizable. In addition, a new approach to aza-heterofullerenes has been developed starting from an exohedrally activated fullerene.     

Possible Role Played by the Fullerene‐like Structures of Interstellar Carbon Dust in the Formation of Molecular Hydrogen in Space

Abstract

After a general introduction to the problem of formation of molecular hydrogen from atomic hydrogen in the interstellar medium and in the dense molecular clouds in particular, and after the explanation of the key role played by the surfaces on this process, it is proposed that the most suitable carbon surface for the formation of molecular hydrogen (from the radiative association process of atomic hydrogen) can be represented by carbon black rather than by graphite. Furthermore, it is proposed that the fullerene‐like structures present in the carbon black graphene sheets are the reaction sites where molecular hydrogen may be formed.     

Structural mechanics of carbon nanotubes: From continuum elasticity to atomistic fracture

Summary Motivated by recent observations of bent, collapsed and twisted carbon nanotubes, we investigate their behavior at large deformations. These hollow molecules behave remarkably similar to their macroscopic homologs. They reversibly switch into different morphological patterns, and each shape change corresponds to an abrupt release of energy and a singularity in the stress-strain curve. These transformations, simulated using a realistic many-body potential, are accurately described by a continuum-shell model. In contrast, a response to axial tension proceeds smoothly up to a fracture threshold, beyond which a monoatomic carbon chain unravels between the tube fragments.     

From Science to Fashion: Photography and the Production of a Surrogate Colony in Weimar Germany

This article examines German colonial cultures in the post-World War I period following Germany’s loss of a colonial empire. Photography had long been embedded in both the practical and ideological production of empire, but after 1918 took on an especially significant role in constructing a ‘surrogate colony’ that kept the colonial idea alive in the absence of direct colonial rule. The dynamics of this surrogate colony are especially evident in the publications of the organised colonial movement. Drawing on these publications, I argue that the colonial movement produced a surrogate colony that was as much about the management of gendered and racialised German populations as it was about propagandising for a return to colonial rule. Photography played a key role in bringing together two areas that underlay this gendered and racialised dynamic: science and commercial culture. I thus begin by tracing the way in which photographic scientific cultures, in particular in the fields of medicine, anthropology, and racial science, shaped the contours of the surrogate colony. These scientific cultures emerged in an unstable relationship with mass commercial photographic cultures, with the article then turning to an exploration of ‘colonial fashion photography’. The foregrounding of clothing and bodies in this photography highlights the complex relationship between scientific and commercial photography, which is shown to be deeply implicated in the production of racialised and gendered forms of embodiment.     

Inside Front Cover: Controlling Morphology in Polymer–Fullerene Mixtures (Adv. Mater. 2/2008)

On p. 240, Klaus Meerholz and co‐workers show control over the aggregation of P3HT in solution by mixing a dipolar, but miscible solvent to the coating solution. The resulting nanoparticle dispersions are stable and allow a quantitative comparison of the absorption spectra of amorphous and aggregated P3HT. These results are interesting not only because they allow control of morphology on the nanometer scale, but they also show a path to low‐cost morphological control of large‐area films, which is an essential step for the commercialization of plastic PV devices.     

Novel Fullerene Containing Liquid Crystalline Dendrimers and Hemi‐dendrimers: Synthesis and Characterization

Abstract

Novel fullerene C₆₀ containing liquid crystalline dendrimers and hemi‐dendrimers have been characterized by the method of electro‐optical Kerr effect and determination of the permanent dipole moment, sensitive to the molecular polar ordering and anisotropy of polarizability, and by hydrodynamic methods in solution. An influence of the covalently bonded fullerene on the polarity, electro‐optical, and viscometric properties of fullerene derivatives have been detected, analyzed, and concluded that fullerene produces a change in the original ordering in dendritic molecules, which mainly resulted in correction of the shape asymmetry of these molecules as a whole.     

Fullerenes and Carbon Nanotubes Formed in an Electric Arc at and Above Atmospheric Pressure

[60]Fullerene and carbon nanotubes have been obtained with an electric arc discharge in helium or argon at the pressure of 0.1-3.0 bar (i.e. from -0.9 up to 2.0 bar above the atmospheric pressure, respectively). The yield of the process is about 10 times higher in helium with a maximum at the pressure of 0.2 bar, while in argon the maximum is observed at 0.4 bar. It is not very important, what kind of the inert gas (He or Ar) is used in a process carried out at the atmospheric pressure and higher. In this case, the yield is usually better or comparable with other alternative methods, e.g. the solar furnace synthesis. We found that the oxygen plays a crucial role reducing the yield of fullerenes and carbon nanotubes. Even traces of O₂ must be removed from the reactor chamber, otherwise yellow coloured fullerene derivatives (oxidation products) are formed instead of C₆₀.     

Radical-scavenging Ability of Hydrophilic Carbon Nanoparticles: From Fullerene to Its Soot

We have recently developed a facile synthetic method for highly water-soluble fullerene, so-called fullerenol, for the treatment of fullerene with hydrogen peroxide. This method was applied to fullerene soot to yield the corresponding new hydrophilic carbon materials, and the obtained products were subjected to infrared spectroscopy and elemental analysis. The DLS particle size analysis demonstrated the relatively high dispersion of hydrophilic fullerene soot with a diameter of ?70 nm in water, while the hydrophilic activated carbon obtained by the same treatment showed the larger aggregation with diameters of 200 and 970 nm. The surface analysis using FE-SEM showed the difference in morphology between fullerene soot and activated carbon as well as between before and after hydrophilic treatment of the soot with hydrogen peroxide. Moreover, this hydrophilic fullerene soot exhibited high antioxidant activity (%AOA) up to 87% compared with fullerenol C₆₀(OH)₃₆ (54%) and C₆₀ (50%) evaluated by β-carotene bleaching method.     

From Engineering Science to Precision Engineering and Ultraprecision Production:Fundamentals,Methodologies and Application Case Studies

正Submission Deadline:May 1,2021 The demand for precision components is on the rise in a variety of engineering industries.Over the last 10years,ultraprecision manufacturing technology has been applied on an industrial scale to ultraprecision production of products such as mobile phones,security monitor systems,head-up displays (HUD) and varifocal lenses,etc.     

Aggregate Science: From Structures to Properties

Molecular science entails the study of structures and properties of materials at the level of single molecules or small interacting complexes of molecules. Moving beyond single molecules and well-defined complexes, aggregates (i.e., irregular clusters of many molecules) serve as a particularly useful form of materials that often display modified or wholly new properties compared to their molecular components. Some unique structures and phenomena such as polymorphic aggregates, aggregation-induced symmetry breaking, and cluster excitons are only identified in aggregates, as a few examples of their exotic features. Here, by virtue of the flourishing research on aggregation-induced emission, the concept of “aggregate science” is put forward to fill the gaps between molecules and aggregates. Structures and properties on the aggregate scale are also systematically summarized. The structure–property relationships established for aggregates are expected to contribute to new materials and technological development. Ultimately, aggregate science may become an interdisciplinary research field and serves as a general platform for academic research.