Theoretical investigation of LaC3n+ (n = 0, 1, 2) clusters by density functional theory

Wu, Zhijian; Meng, Qingguo; Zhang, S. Y.

doi:10.1002/(sici)1097-461x(1998)66:4<301::aid-qua6>3.0.co;2-z

Cited by 2 publications

(2 citation statements)

References 29 publications

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“…Many experimental and theoretical studies have been undertaken on small metal carbide clusters such as ScC n , YC n , LaC n , ( n < 10). A general conclusion from these studies is that a “fan structure ” in which the metal atom sits above the carbon chain and bonds to each carbon is the most stable structure for those metals that form endohedral metallofullerenes. − Suzuki et al. have also shown that there is a correlation between the formation of MC n + ( n < 4) and the formation of MC 82 + , which indicates that these very small metal carbides can provides clues to the formation of M@C 82 + . , …”

Section: Resultsmentioning

confidence: 98%

“…A general conclusion from these studies is that a "fan structure" in which the metal atom sits above the carbon chain and bonds to each carbon is the most stable structure for those metals that form endohedral metallofullerenes. [88][89][90][91][92][93][94][95] Suzuki et al have also shown that there is a correlation between the formation of MC n + (n < 4) and the formation of MC 82 + , which indicates that these very small metal carbides can provides clues to the formation of M@C 82 + . 96,97 Collision-Induced Dissociation of Small Metal Carbides.…”

Section: Resultsmentioning

confidence: 99%

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Laser Ablation Mass Spectrometry of Pyrolyzed Koppers Coal-Tar Pitch: A Precursor for Fullerenes and Metallofullerenes

et al. 1999

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Pyrolyzed Koppers coal-tar pitch samples consisting mainly of polycyclic aromatic hydrocarbons were studied by direct laser vaporization Fourier transform ion cyclotron resonance and time-of-flight mass spectrometry. Fullerene cations were readily formed from these carbonaceous precursors over a wide range of low-laser ablation power densities. The laser-desorption ionization of the pyrolyzed coal-tar pitches shows the presence of a range of polyaromatic hydrocarbons some containing as many as 70 carbon atoms, which should require only small amounts of laser energy to convert them into fullerenes. Metallofullerene formation also occurs with low power laser ablation of pyrolyzed mixtures of metal oxides, metal sulfides, or metal carbonates and the Koppers coal-tar pitch. Ablation with two different laser pulse widths of 230 µs and 8 ns, at a laser wavelength of 1064 nm, shows that only the long-pulse low-power (200-2000 kW cm -2 ) laser radiation produces metallofullerene ions. The short-pulse high-power (1-2300 MW cm -2 ) laser ablation results only in the formation of small metal carbide cluster and fullerene ions. Collision-induced dissociation experiments were used to study the structures of the small metal carbide clusters and the endohedral metallofullerene ion, La@C 60 + . IntroductionShortly after the discovery of the hollow carbon cage molecules now known as fullerenes, Heath et al. reported that lanthanum atom(s) could be encapsulated in the fullerene cage. 1 The name endohedral metallofullerene written as A m @C 2n , where the symbol @ denotes that the metal atom (A) is located inside fullerene cage and m ) 1-3, n ) 30-70, has been assigned to this new family of fullerenes. 2,3 The novel properties and possible applications of these new molecules as nonlinear optical devices and catalysts, 4 superconductors, 5 lasers, and ferroelectric materials 4,6 have encouraged many researchers to commence macroscale production 3,7-9 and spectroscopic characterization 10-19 of metallofullerenes.Laboratory scale chemical studies on endohedral metallofullerenes are difficult because these species can only be produced with very low yields and so there is a demand for other methods of production or the discovery of new precursors. 20 To date, most of preparations have used graphite/metal or metal oxide mixtures as precursors with different vaporization sources. 8,9,21,22 Our studies on the other hand have been focused on the search for new fullerene and metallofullerene carbon precursors. [22][23][24][25][26][27][28][29][30][31][32][33][34] The use of metal-doped graphite rods with the arc vaporization method 35 and the laser ablation-furnace method 36,37 represent the two major methods for metallofullerene production. Of these two methods, the arc technique is preferred for macroscopic production and yields of less than 0.1% are still common for even the most abundant of the metallofullerenes (for example, La@C 82 ) 38 that can be isolated.

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Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

Laser Ablation Mass Spectrometry of Pyrolyzed Koppers Coal-Tar Pitch: A Precursor for Fullerenes and Metallofullerenes

et al. 1999

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Continuation calculations of boron- (aluminum-, titanium-, and nickel-) doped La13 clusters

Zhang

Shen

Chen

2005

The Journal of Chemical Physics

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In this work, we have calculated boron-, aluminum-, titanium-, and nickel-doped La13 clusters by DMOL method based on the density-functional theory. Two doping modes are employed: surface and center doping. The boron, aluminum, and nickel atoms prefer to occupy the surface sites while the titanium atom prefers to occupy the center site. The doped La13 clusters with these four kinds of atoms have lower binding energy than pure La13 clusters. The icosahedral isomers are of lower binding energy than cubotahedral and decahedral isomers for La12B(-1), La12Al(-1), and La12Ni, while doping makes the cubotahedral La12Ti stable with a binding energy a little lower than icosahedral La12Ti. There are electronic shell effects in icosahedral La12B(-1) and La12Al(-1). The icosahedral La12B(-1) is promising to be formed during the doped process experimentally. Furthermore, we have also discussed the distorted structures of center doping by bond lengths, density of states, and charge transfers.

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Theoretical investigation of LaC3n+ (n = 0, 1, 2) clusters by density functional theory

Cited by 2 publications

References 29 publications

Laser Ablation Mass Spectrometry of Pyrolyzed Koppers Coal-Tar Pitch: A Precursor for Fullerenes and Metallofullerenes

Laser Ablation Mass Spectrometry of Pyrolyzed Koppers Coal-Tar Pitch: A Precursor for Fullerenes and Metallofullerenes

Continuation calculations of boron- (aluminum-, titanium-, and nickel-) doped La13 clusters

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