Formation and reinforcement of clusters composed of C60 molecules.
TL;DR: It was found that the clusters are reinforced; that is, they are not broken by electron beams any more, and the actual mechanism of the reinforcement of the clusters has not yet been clearly understood and therefore is an open question.
Abstract: We carry out two experiments: (1) the formation of clusters composed of C60 molecules via self-assembly and (2) the reinforcement of the clusters. Firstly, clusters such as fibres and helices composed of C60 molecules are produced via self-assembly in supercritical carbon dioxide. However, C60 molecules are so weakly bonded to each other in the clusters that the clusters are broken by the irradiation of electron beams during scanning electron microscope observation. Secondly, UV photons are irradiated inside a chamber in which air is filled at 1 atm and the above clusters are placed, and it was found that the clusters are reinforced; that is, they are not broken by electron beams any more. C60 molecules located at the surface of the clusters are oxidised, i.e. C60On molecules, where n = 1, 2, 3 and 4, are produced according to time-of-flight mass spectroscopy. It is supposed that oxidised C60 molecules at the surface of the clusters may have an important role for the reinforcement, but the actual mechanism of the reinforcement of the clusters has not yet been clearly understood and therefore is an open question.
Citations
More filters
TL;DR: Okabe et al. as mentioned in this paper described the photochemistry of small molecules and their role in the development and evolution of the human body's ability to communicate with other small molecules, including DNA.
Abstract: Photochemistry of Small Molecules. By Hideo Okabe. Pp. 431. (Wiley: Chichester, UK, and New York, 1978.) £24.55.
122 citations
TL;DR: In this article, the authors proposed metaloxide-semiconductor field effect transistor (MOSFET) types featuring additional L-shaped counterdoped areas in the source and/or drain regions of silicon-on-insulator (SOI) MOSFets to reduce drain-induced barrier lowering (DIBL) through the buried oxide (BOX) layer.
Abstract: In this paper, the authors propose novel metal-oxide-semiconductor field-effect transistor (MOSFET) types featuring additional L-shaped counterdoped areas in the source and/or drain regions of silicon-on-insulator (SOI) MOSFETs to reduce drain-induced barrier lowering (DIBL) through the buried oxide (BOX) layer. The L-shaped region in the drain area shields the BOX layer from penetration by the drain electric field, thereby reducing DIBL in the body region. Simulation of the electrical characteristics of these novel MOSFETs demonstrated more remarkable DIBL suppression and subthreshold slope performance in short-channel regions than in conventional SOI MOSFETs. In addition to this suppression, these novel MOSFETs suppress breakdown voltage more effectively than conventional SOI MOSFETs. The authors concluded that the proposed devices are capable of contributing to the scaling of SOI MOSFETs in ultralarge-scale integration circuits.
23 citations
TL;DR: In this article, the authors irradiate sub- and supercritical benzene, in which metallocene such as ferrocene or cobaltocene is dissolved, with a UV laser of 266nm wavelength, and show that benzene and metallocenes are dissociated and iron-and cobalt-containing carbon onions (Fe@C and Co@C) are created.
Abstract: We irradiate sub- and super-critical benzene, in which metallocene such as ferrocene or cobaltocene is dissolved, with a UV laser of 266nm wavelength, and show that benzene and metallocenes are dissociated and iron- and cobalt-containing carbon onions (Fe@C and Co@C) are created. The operational temperature of the present method is much lower than that of conventional ones for the growth of nanomaterials and therefore coagulation among metal-containing carbon onions is avoided. The average diameters of the core iron and cobalt nanoparticles are, respectively, 7.5 and 7.2nm, whereas the thickness of the layers of carbon onions surrounding the core metal particles is 3.2nm in both Fe@C and Co@C cases. The metal-containing carbon onions show superparamagnetic characteristics.
8 citations
TL;DR: In this paper, particle-like and whisker-like nano/micro clusters, which are composed of C60 molecules, deposit on the surface of a silicon substrate placed vertically in C60/benzene solution during the temperature change.
Abstract: We dissolve C60, C70 or C84 molecules in benzene and change the fluid state from a gas–liquid two-phase region (250 °C) to the critical point (2890 °C) and from the critical point to the original state (250 °C) along the gas–liquid coexistence curve We find that particle-like and whisker-like nano/micro clusters, which are composed of C60 molecules, deposit on the surface of a silicon substrate placed vertically in C60/benzene solution during the temperature change, whereas no appreciable clusters are detected on the silicon substrate in either C70/benzene or C84/benzene solutions The clusters, in which fcc lattice structures are formed by C60 molecules, remain stable in the solution The present result suggests that C60 molecules can be separated and extracted from a mixture of C60, C70 and C84 molecules dissolved in benzene
3 citations
TL;DR: This poster presents a probabilistic procedure to estimate the intensity of the response of the immune system to radiation in the presence of certain materials and conditions.
Abstract: NSFC [51271156]; National Defense Basic Scientific Research program of China [B1420110155]; Natural Science Foundation of Fujian Province of China [2012J05125, 2011J01373]; Foundation of Key Laboratory of System Control and Information Processing, Ministry of Education, P.R. China [SCIP2011004]
1 citations
Cites background from "Formation and reinforcement of clus..."
...Extensive experimental and theoretical investigations, including structure studies, of C60 and related clusters have been performed in recent decades [2], [3]....
[...]
References
More filters
Book•
01 Jan 1972
TL;DR: The field of phase transitions and critical phenomena continues to be active in research, producing a steady stream of interesting and fruitful results as discussed by the authors, and the major aim of this serial is to provide review articles that can serve as standard references for research workers in the field.
Abstract: The field of phase transitions and critical phenomena continues to be active in research, producing a steady stream of interesting and fruitful results. It has moved into a central place in condensed matter studies. Statistical physics, and more specifically, the theory of transitions between states of matter, more or less defines what we know about 'everyday' matter and its transformations. The major aim of this serial is to provide review articles that can serve as standard references for research workers in the field, and for graduate students and others wishing to obtain reliable information on important recent developments.
12,039 citations
Journal Article•
2,551 citations
01 Jan 2009
TL;DR: In this paper, the magnetic properties of magnetic nanoparticles have been investigated and a number of methods for nanoparticle synthesis including the preparation of metallic magnetic particles have been described in the literature, including the control of particle size, shape, and monodispersity as well as their stability towards oxidation.
Abstract: As compared to bulk materials, magnetic nanoparticles possess distinct magnetic properties and attempts have been made to exploit their beneficial properties for technical and biomedical applications, e.g. for magnetic fluids, high-density magnetic recording, or biomedical diagnosis and therapy. Early magnetic fluids (MFs) were produced by grinding magnetite with heptane or long chain hydrocarbon and a grinding agent, e.g. oleic acid [152]. Later procedures for MFs precipitated Fe 3+/Fe 2+ of an aqueous solution with a base, coated the particles by oleic acid, and dispersed them in carrier liquid [161]. However, besides the elemental composition and crystal structure of the applied magnetic particles, particle size and particle size distribution determine the properties of the resulting MF. Many methods for nanoparticle synthesis including the preparation of metallic magnetic particles have been described in the literature. However, there still remain important questions, e.g. concerning control of particle size, shape, and monodispersity as well as their stability towards oxidation. Moreover, peptization by suitable surfactants or polymers into stable MFs is an important issue since each application in engineering or biomedicine needs special MFs with properties adjusted to the requirements of the system.
980 citations
TL;DR: In this paper, it was shown that the C4 ring connecting the cages is square rather than rectangular and that the latter is predicted theoretically, whereas the former was predicted theoretically by the authors of this paper.
Abstract: The discovery and large-scale synthesis of fullerenes have aroused interdisciplinary interest in these closed-cage molecules1,2,3,4,5,6 C60 can be photopolymerized into a form in which the cages are thought to be linked by cyclic C4 units in a [2 + 2] cycloaddition7, provoking theoretical studies of the C60 dimer8,9,10,11,12,13,14,15, the smallest subunit of such a polymer The C60 dimers C120O (refs 16, 17), C121H2( ref 17) and C120O2(ref 18) have been reported, in which the two C60molecules are linked by, respectively, a furan group, a cyclopentane ring and a cyclobutane ring plus two oxygen bridges; but the simplest dimer, C120linked by a cyclobutane ring alone, has not so far been observed We now report that this dumb-bell-shaped molecule can be synthesized by a solid-state mechanochemical reaction of C60 with potassium cyanide Our X-ray structural analysis shows that the C4 ring connecting the cages is square rather than rectangular—the latter is predicted theoretically8,9,13,14,15 The dimer dissociates cleanly into two C60 molecules on heating or one-electron reduction, but in the gas phase during mass-spectrometric measurements it undergoes successive loss of C2 units, shrinking to even-numbered fullerenes such as C118 and C116 in a sequence similar to that seen for other large fullerenes19,20
457 citations
"Formation and reinforcement of clus..." refers background in this paper
...Introduction It is known that clusters composed of C60 molecules such as chains and sheets can be formed by polymerising C60 molecules via the irradiation of photons [1-13], application of high pressure and/or high temperature [3,5,6,14-17], or introduction of foreign atoms or molecules [18-20]....
[...]