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Y. Chai

Bio: Y. Chai is an academic researcher from Rice University. The author has contributed to research in topics: Fullerene & Ionization. The author has an hindex of 11, co-authored 14 publications receiving 3171 citations.

Papers
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Journal ArticleDOI
TL;DR: Fullerenes with a single lanthanum atom trapped on the inside of the carbon cage were produced by laser vaporization of a graphite composite rod in a flow of argon gas at 1200 °C as discussed by the authors.
Abstract: 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 1200 °C. When sublimed with C_(60) and C_(70), they formed an air-stable film containing principally LaC_(60), LaC_(70), LaC_(74), and LaC_(82). When dissolved in toluene and exposed to air, LaC_(82) was found to be uniquely stable. Evidence was also obtained for coalescence reactions between these fullerenes at high temperatures to form larger cages with as many as three lanthanum atoms inside. Indications have also been obtained for the successful production of KC_(60), C_(59)B, and KC_(59)B where the boron has substituted for a carbon in the soccerball cage. The use of the @ symbol is advocated for specifying such complex fullerenes as (K@C_(59)B).

1,079 citations

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TL;DR: Buckminsterfullerene, C{sub 60}, was prepared in gram quantities by contact-arc vaporization of a graphite rod in a 100-Torr atmosphere of helium, followed by extraction of the resultant graphite soot with toluene as discussed by the authors.
Abstract: Buckminsterfullerene, C{sub 60}, was prepared in gram quantities by contact-arc vaporization of a graphite rod in a 100-Torr atmosphere of helium, followed by extraction of the resultant graphite soot with toluene. The dominance of C{sub 60} in this extract was verified by mass, FTIR, and NMR spectroscopy. The molecule was successfully hydrogenated to C{sub 60}H{sub 36} via a Birch reduction and dehydrogenated back to bare C{sub 60} by treatment with DDQ reagent. Cyclic voltammetry of C{sub 60} in methylene chloride revealed highly reversible formation of at least two stable anionic forms of C{sub 60} in solution. A broad new class of these fulleride and fulleronium ions is anticipated, both with the internal cavity empty and with any one of a large number of elements inside, thus providing a means of fine-tuning the chemical, optical, and redox properties.

882 citations

Journal ArticleDOI
18 Sep 1992-Science
TL;DR: Stable closed-shell derivatives of C28 with large highest occupied molecular orbital—lowest unoccupied molecular orbital gaps should be attainable either by reacting at the four tetrahedral vertices on the outside of the C28 cage to make, for example, C28H4, or by trapping a tetravalent atom inside the cage toMake endothedral fullerenes such as Ti@C28.
Abstract: Laser vaporization experiments with graphite in a supersonic cluster beam apparatus indicate that the smallest fullerene to form in substantial abundance is C28. Although ab initio quantum chemical calculations predict that this cluster will favor a tetrahedral cage structure, it is electronically open shell. Further calculations reveal that C28 in this structure should behave as a sort of hollow superatom with an effective valence of 4. This tetravalence should be exhibited toward chemical bonding both on the outside and on the inside of the cage. Thus, stable closed-shell derivatives of C28 with large highest occupied molecular orbital—lowest unoccupied molecular orbital gaps should be attainable either by reacting at the four tetrahedral vertices on the outside of the C28 cage to make, for example, C28H4, or by trapping a tetravalent atom inside the cage to make endothedral fullerenes such as Ti@C28. An example of this second, inside route to C28 stabilization is reported here: the laser and carbon-arc production of U@C28.

398 citations

Journal ArticleDOI
TL;DR: In this article, X-ray photoemission spectral probes of endohedral lanthanum-fullerene complexes, La@C n, show that the central La atom is in a formal charge state close to +3, and has been effectively protected from reaction with water an oxygen by the enclosing fullerene cage.

218 citations

Journal ArticleDOI
TL;DR: In this paper, the lifetime of the lowest triplet state of the two most stable fullerenes, C 60 and C 70, was measured in a supersonic beam by two-color resonant two-photon ionization.

166 citations


Cited by
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TL;DR: In this paper, a force field for large-scale reactive chemical systems (1000s of atoms) is proposed. But the force field does not have Coulomb and Morse potentials to describe nonbond interactions between all atoms.
Abstract: To make practical the molecular dynamics simulation of large scale reactive chemical systems (1000s of atoms), we developed ReaxFF, a force field for reactive systems. ReaxFF uses a general relationship between bond distance and bond order on one hand and between bond order and bond energy on the other hand that leads to proper dissociation of bonds to separated atoms. Other valence terms present in the force field (angle and torsion) are defined in terms of the same bond orders so that all these terms go to zero smoothly as bonds break. In addition, ReaxFF has Coulomb and Morse (van der Waals) potentials to describe nonbond interactions between all atoms (no exclusions). These nonbond interactions are shielded at short range so that the Coulomb and van der Waals interactions become constant as Rij → 0. We report here the ReaxFF for hydrocarbons. The parameters were derived from quantum chemical calculations on bond dissociation and reactions of small molecules plus heat of formation and geometry data for...

4,455 citations

Journal ArticleDOI
22 Oct 1992-Nature
TL;DR: The response of carbon soot particles and tubular graphitic structures to intense electron-beam irradiation in a high-resolution electron microscope is reported, suggesting that planar graphite may not be the most stable allotrope of carbon in systems of limited size.
Abstract: THE discovery1 of buckminsterfullerene (C60) and its production in macroscopic quantities2 has stimulated a great deal of research. More recently, attention has turned towards other curved graphitic networks, such as the giant fullerenes (Cn, n > 100)3,4 and carbon nanotubes5–8. A general mechanism has been proposed9 in which the graphitic sheets bend in an attempt to eliminate the highly energetic dangling bonds present at the edge of the growing structure. Here, I report the response of carbon soot particles and tubular graphitic structures to intense electron-beam irradiation in a high-resolution electron microscope; such conditions resemble a high-temperature regime, permitting a degree of structural fluidity. With increased irradiation, there is a gradual reorganization of the initial material into quasi-spherical particles composed of concentric graphitic shells. This lends weight to the nucleation scheme proposed9 for fullerenes, and moreover, suggests that planar graphite may not be the most stable allotrope of carbon in systems of limited size.

1,733 citations

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1,162 citations

Journal ArticleDOI
TL;DR: Although progress has recently been made toward understanding the health and environmental consequences of these materials, challenges ramain for future research are still challenges.
Abstract: Although progress has recently been made toward understanding the health and environmental consequences of these materials, challenges ramain for future research.

1,126 citations

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TL;DR: In this article, the progress of lithium storage in different carbon forms starting from intercalation in graphite to the storage in fullerenes, nanotubes, diamond and most recently, graphene is discussed.
Abstract: In this review article we discuss the progress of lithium storage in different carbon forms starting from intercalation in graphite to the lithium storage in fullerenes, nanotubes, diamond and most recently, graphene. The recent advances in lithium storage in various novel morphological variants of carbons prepared by a variety of techniques are also discussed with the most important models in literature that have been set out to explain the excess lithium storage. The major emphasis lies on the real structure.

1,035 citations