C 60 : Buckminsterfullerene
TL;DR: In this article, the authors proposed a truncated icosahedron, a polygon with 60 vertices and 32 faces, 12 of which are pentagonal and 20 hexagonal.
Abstract: During experiments aimed at understanding the mechanisms by which long-chain carbon molecules are formed in interstellar space and circumstellar shells1, graphite has been vaporized by laser irradiation, producing a remarkably stable cluster consisting of 60 carbon atoms. Concerning the question of what kind of 60-carbon atom structure might give rise to a superstable species, we suggest a truncated icosahedron, a polygon with 60 vertices and 32 faces, 12 of which are pentagonal and 20 hexagonal. This object is commonly encountered as the football shown in Fig. 1. The C60 molecule which results when a carbon atom is placed at each vertex of this structure has all valences satisfied by two single bonds and one double bond, has many resonance structures, and appears to be aromatic. Before 1985, it was generally accepted that elemental carbon exists in two forms, or allotropes: diamond and graphite. Then, Kroto et al. identified the signature of a new, stable form of carbon that consisted of clusters of 60 atoms. They called this third allotrope of carbon 'buckminsterfullerene', and proposed that it consisted of polyhedral molecules in which the atoms were arrayed at the vertices of a truncated icosahedron. In 1990, the synthesis of large quantities of C60 [see Nature 347, 354–358 (1990)] confirmed this hypothesis.
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NEC1
TL;DR: Iijima et al. as mentioned in this paper reported the preparation of a new type of finite carbon structure consisting of needle-like tubes, which were produced using an arc-discharge evaporation method similar to that used for fullerene synthesis.
Abstract: THE synthesis of molecular carbon structures in the form of C60 and other fullerenes1 has stimulated intense interest in the structures accessible to graphitic carbon sheets. Here I report the preparation of a new type of finite carbon structure consisting of needle-like tubes. Produced using an arc-discharge evaporation method similar to that used for fullerene synthesis, the needles grow at the negative end of the electrode used for the arc discharge. Electron microscopy reveals that each needle comprises coaxial tubes of graphitic sheets, ranging in number from 2 up to about 50. On each tube the carbon-atom hexagons are arranged in a helical fashion about the needle axis. The helical pitch varies from needle to needle and from tube to tube within a single needle. It appears that this helical structure may aid the growth process. The formation of these needles, ranging from a few to a few tens of nanometres in diameter, suggests that engineering of carbon structures should be possible on scales considerably greater than those relevant to the fullerenes. On 7 November 1991, Sumio Iijima announced in Nature the preparation of nanometre-size, needle-like tubes of carbon — now familiar as 'nanotubes'. Used in microelectronic circuitry and microscopy, and as a tool to test quantum mechanics and model biological systems, nanotubes seem to have unlimited potential.
39,086 citations
TL;DR: In this article, a new form of pure, solid carbon has been synthesized consisting of a somewhat disordered hexagonal close packing of soccer-ball-shaped C60 molecules.
Abstract: A new form of pure, solid carbon has been synthesized consisting of a somewhat disordered hexagonal close packing of soccer-ball-shaped C60 molecules. Infrared spectra and X-ray diffraction studies of the molecular packing confirm that the molecules have the anticipated 'fullerene' structure. Mass spectroscopy shows that the C70 molecule is present at levels of a few per cent. The solid-state and molecular properties of C60 and its possible role in interstellar space can now be studied in detail.
6,650 citations
TL;DR: In this article, the authors focus on the origin of the D and G peaks and the second order of D peak and show that the G and 2 D Raman peaks change in shape, position and relative intensity with number of graphene layers.
6,496 citations
TL;DR: X-ray diffraction and electron microscopy showed that fullerene single-wall nanotubes (SWNTs) are nearly uniform in diameter and that they self-organize into “ropes,” which consist of 100 to 500 SWNTs in a two-dimensional triangular lattice with a lattice constant of 17 angstroms.
Abstract: The major part of this chapter has already appeared in [1], but because of the length restrictions (in Science), the discussion on why we think this form is given in only brief detail. This chapter goes into more depth to try to answer the questions of why the fullerenes form themselves. This is another example of the very special behavior of carbon. From a chemist’s standpoint, it is carbon’s ability to form multiple bonds that allows it to make these low dimensional forms rather than to produce tetrahedral forms. Carbon can readily accomplish this and it is in the mathematics and physics of the way this universe was put together, that carbon is given this property. One of the consequences of this property is that, if left to its own devices as carbon condenses from the vapor and if the temperature range is just right, above 1000°C, but lower than 1400°C, there is an efficient self-assembly process whose endpoint is C60.
5,215 citations
TL;DR: A review of recent advances in carbon nanotubes and their composites can be found in this article, where the authors examine the research work reported in the literature on the structure and processing of carbon Nanotubes.
4,709 citations
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TL;DR: In this paper, a supersonic beam of carbon clusters is generated using graphite as the substrate, and carbon clusters Cn for n=1−190 have been produced having a distinctly bimodal cluster size distribution: (i) both even and odd clusters for Cn, 1≤n≤30; and (ii) only even clusters C2n, 20−n−90.
Abstract: Laser vaporization of a substrate within the throat of a pulsed nozzle is used to generate a supersonic beam of carbon clusters. The neutral cluster beam is probed downstream by UV laser photoionization with time‐of‐flight mass analysis of the resulting photoions. Using graphite as the substrate, carbon clusters Cn for n=1–190 have been produced having a distinctly bimodal cluster size distribution: (i) Both even and odd clusters for Cn, 1≤n≤30; and (ii) only even clusters C2n, 20≤n≤90. The nature of the bimodal distribution, and the intensity alterations in the observed C+n signals are interpreted on the basis of cluster formation and stability arguments. Ionizing laser power dependences taken at several different photon energies are used to roughly bracket the carbon cluster ionization potentials, and, at high laser intensity, to observe the onset of multiphoton fragmentation. By treating the graphite rod with KOH, a greatly altered carbon cluster distribution with mixed carbon/potassium clusters of for...
782 citations
TL;DR: In this paper, cold beams of metal clusters are produced by combining a laser vaporization technique with pulsed supersonic nozzle technology, and the results show that the resulting cold beams are more stable than those of traditional laser-based methods.
Abstract: Cold beams of metal clusters are produced by combining a laser vaporization technique with pulsed supersonic nozzle technology. (AIP)
750 citations
364 citations
TL;DR: In this article, a novel technique involving pulsed laser vaporization of the bulk metal within a pulsed supersonic nozzle has been shown to successfully produce ultracold bare metal clusters of even the most refractory of metals, tungsten and molybdenum.
Abstract: A novel technique involving pulsed laser vaporization of the bulk metal within a pulsed supersonic nozzle has been shown to successfully produce ultracold bare metal clusters of even the most refractory of metals, tungsten and molybdenum. Clusters of up to 25 atoms may be readily prepared using this technique. Mass‐selective resonant two‐photon ionization spectra of Mo2 produced in this fashion show that the dimer is efficiently cooled in the expansion Ttrans<6 K, Trot∼5 K, and Tvib∼325 K. We have rotationally resolved the A 1Σ+u←X 1Σ+g (0–0) band for 92Mo2 and determined the bond length in the ground and excited states to be 1.940±0.009 and 1.937±0.008 A, respectively. This confirms and extends the analysis of Efremov et al. [J. Mol. Spectrosc. 73, 40 (1970)] who prepared 98Mo2 by flash photolysis of isotopically pure Mo(CO)6. We have also observed the (1–1), (2–2), and (3–3) sequence bands which together with the ground state data of Efremov et al. determine vibrational constants ω′e=449.0±0.2 cm−1 and ...
298 citations
TL;DR: In this article, the authors used a pulsed supersonic nozzle to produce ultracold beams of copper clusters using an argon fluoride excimer laser followed by mass spectrometric analysis showed the cold beam to contain clusters in the range from 1 through 13 copper atoms.
Abstract: Laser vaporization of a rotating metal target within a pulsed supersonic nozzle has been used to produce ultracold beams of copper clusters Photoionization with an argon fluoride excimer laser followed by time-of-flight mass spectrometric analysis showed the cold beam to contain clusters in the range from 1 through 13 copper atoms The ionization potential (IP) of the small clusters was seen to alternate above and below the 64-eV laser photon energy depending upon whether the cluster contained an een (high IP) or odd (low IP) number of copper atoms The absorption spectrum of Cu/sub 2/ was recorded in the 4480 to 4660-A region by using two-color resonant two-photon ionization The Cu/sub 2/ cluster beam was found to have translational, rotational, and vibrational temperatures of < 5, < 10, and 50 to 100/sup 0/K, respectively In addition to the known B /sup 1/sigma/sup +//sub u/ reverse arrow X /sup 1/sigma/sup +//sub g/ band system, a new system was found in the same spectral range Parameters for the new system were T/sub e/ = 21,867 +- 4 cm/sup -1/, omega'/sub e/ = 226 +- 3 cm/sup -1/, omega/sub e/ chi'/sub e/ = 3 +- 2 cm/sup -1/ The lifetime of the Bmore » state was found to be 35 +- 10 ns for the vibrational levels nu' = 0 and 1, and it is argued this short lifetime is likely due to predissociation The lifetime of the new C state was found to be 10 +- 02 mus 4 figures, 1 table« less
232 citations