High-resolution electron microscopy of Gd@C82 metal fullerenes grown on MgO(001) surfaces

Tanaka, Nobuo; Honda, Yoshitake; Kawahara, Michiharu; Kishida, Masaaki; Shinohara, Hisanori

doi:10.1016/0040-6090(96)08693-2

Cited by 17 publications

(5 citation statements)

References 18 publications

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“…[12][13][14][15] For example, the synchrotron x-ray diffraction experiment on a powder Y@C 82 sample revealed the presence of such a charge transfer from the analysis of the total electron density distribution of an Y@C 82 microcrystal. 16 EXAFS and high-resolution transmission microscope measurements showed that the M is displaced significantly from the center, 9,17 which is supported by theoretical calculations. [18][19][20][21] As a result of the off-center nature of the M atom, a permanent dipole moment for M @C 82 is expected.…”

Section: Introductionsupporting

confidence: 60%

Nucleation of endohedral metallofullereneNd@C82onC
Lin
¹
,
Huang
²
,
Yang
³

et al. 1998
Phys. Rev. B
19
2
16
0
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We have studied the initial stage growth of endohedral metallofullerene Nd@C 82 on crystalline C 60 films using in situ ultrahigh vacuum scanning tunneling microscopy. We find that Nd@C 82 molecules aggregate into two-dimensional close-packed configurations. Over 60% of molecules form triangle-shaped trimers with identical orientation with respect to the underlying C 60 films. Our observations are attributed to a permanent dipole moment of Nd@C 82 molecules. We also use a dipole-dipole interaction model to calculate their binding energy and the result shows that the dipole moments of Nd@C 82 molecules will displace off the molecular center while they form trimers. ͓S0163-1829͑98͒02728-3͔

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Section: Introductionsupporting

confidence: 60%

Nucleation of endohedral metallofullereneNd@C82onC
Lin
¹
,
Huang
²
,
Yang
³

et al. 1998
Phys. Rev. B
19
2
16
0
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“…Figure 8 shows the HRTEM image of Sc 2 @C 84 , suggesting the endohedral nature of the metallofullerene. Further evidence on endohedral nature based on HRTEM images was reported on Gd@C 82 by Tanaka et al (1996). The UCLA group reported a high-energy collision experiment on La 2 @C 80 against silicon surfaces and found that no collision fragments such as La atoms and C 80 were observed, also suggesting an endohedral structure of La 2 @C 80 (Alvarez et al 1991).…”

Section: Endohedral or Exohedral?mentioning

confidence: 85%

Endohedral metallofullerenes

2000

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Endohedral metallofullerenes (fullerenes with metal atom(s) encapsulated) are novel forms of fullerene-based materials which have attracted wide interest during the past eight years, not only in physics and chemistry but also in such interdisciplinary areas as materials and biological sciences. In this paper, advances in the production, separation (isolation) and various spectroscopic characterizations of endohedral metallofullerenes are presented in an attempt to clarify their structural, electronic and solid state properties. Endohedral metallofullerenes are normally produced by DC electric arc discharge of metal/graphite composite rods used as positive electrodes. The metallofullerenes can also be produced by the so-called laser furnace method which incorporates laser vaporization of the composite rods under high temperature (ca 1000 • C). The endohedral metallofullerenes so far produced are centred on group 2 and 3 metallofullerenes such as Sc, Y, La, Ca, Sr and Ba as well as lanthanide metallofullerenes (Ce-Lu). These metal atoms have been encapsulated in higher fullerenes, especially in C 82 . These metallofullerenes have easily been extracted by solvents from primary soot. By using an elaborate high-performance liquid chromatography technique, the metallofullerenes are completely purified and isolated like C 60 and C 70 . Synchrotron x-ray diffraction, 13 C NMR and ultra-high vacuum scanning tunnelling microscopy (UHV-STM) studies have revealed that metal atoms are indeed encapsulated by the carbon cage and that the metal atoms are not in the centre of the fullerene cage but very close to the carbon cage, indicating the presence of a strong metal-cage interaction. It has been revealed by electron spin resonance and also by theoretical calculations that substantial electron transfers take place from the encaged metal atom to the carbon cage: intrafullerene electron transfers. Good examples are lanthanum and yttrium metallofullerenes which have the charge states of La 3+ @C 3− 82

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“…Endohedral metallofullerenes have so far attracted particular interest because of their novel geometrical and electronic properties together with their inherent charge-transfer nature from metal atoms to fullerenes . It has been revealed by synchrotron X-ray diffraction, 13 C NMR spectroscopy, and ultrahigh vacuum scanning tunneling microscopy (UHV−STM) that within metallofullerenes the metal atoms have indeed been encapsulated inside the carbon cages. Electron spin resonance (ESR), synchrotron ultraviolet photoelectron spectroscopy (UPS), as well as theoretical calculations have revealed that substantial intrafullerene electron transfers are occurring from the encaged metal atoms to carbon cages.…”

Section: Introductionmentioning

confidence: 99%

Production, Isolation, and EELS Characterization of Ti₂@C₈₄ Dititanium Metallofullerenes

et al. 2002

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Three isomers of Ti 2 @C 84 metallofullerenes, Ti 2 @C 84 (I,II,III), have been isolated by the so-called multistage high-performance liquid chromatography (HPLC) method and characterized by laser-desorption time-of-flight mass spectrometry (LD-TOF MS), UV-vis-NIR absorption, and electron energy loss spectroscopy (EELS). Both the HPLC elution behaviors and UV-vis-NIR absorption spectra of these isomers are different from those of the other M 2 @C 84 type metallofullerenes of groups 2 and 3 and lanthanide metal atoms. The results indicate that the Ti 2 @C 84 isomers possess unique electronic structures, which are substantiated by EELS analyses on the valence state of Ti atoms within these metallofullerenes.

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High-resolution electron microscopy of Gd@C82 metal fullerenes grown on MgO(001) surfaces

Cited by 17 publications

References 18 publications

Nucleation of endohedral metallofullereneNd@C82onC
Lin
¹
,
Huang
²
,
Yang
³

et al. 1998
Phys. Rev. B
19
2
16
0
View full text Add to dashboard Cite

Nucleation of endohedral metallofullereneNd@C82onC
Lin
¹
,
Huang
²
,
Yang
³

et al. 1998
Phys. Rev. B
19
2
16
0
View full text Add to dashboard Cite

Endohedral metallofullerenes

Production, Isolation, and EELS Characterization of Ti₂@C₈₄ Dititanium Metallofullerenes

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High-resolution electron microscopy of Gd@C82 metal fullerenes grown on MgO(001) surfaces

Cited by 17 publications

References 18 publications

Nucleation of endohedral metallofullereneNd@C82onCLin1, Huang2, Yang3 et al. 1998Phys. Rev. B192160View full textAdd to dashboardCite

Nucleation of endohedral metallofullereneNd@C82onCLin1, Huang2, Yang3 et al. 1998Phys. Rev. B192160View full textAdd to dashboardCite

Endohedral metallofullerenes

Production, Isolation, and EELS Characterization of Ti2@C84 Dititanium Metallofullerenes

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Nucleation of endohedral metallofullereneNd@C82onC
Lin
¹
,
Huang
²
,
Yang
³

et al. 1998
Phys. Rev. B
19
2
16
0
View full text Add to dashboard Cite

Nucleation of endohedral metallofullereneNd@C82onC
Lin
¹
,
Huang
²
,
Yang
³

et al. 1998
Phys. Rev. B
19
2
16
0
View full text Add to dashboard Cite

Production, Isolation, and EELS Characterization of Ti₂@C₈₄ Dititanium Metallofullerenes