Scanning Tunneling Microscopy/Spectroscopy Studies of Lanthanum Endohedral Metallofullerenes

Taninaka, Atsushi; Shino, Kazuhiro; Sugai, Toshiki; Heike, Seiji; Terada, Yasuhiko; Hashizume, Tomihiro; Shinohara, Hisanori

doi:10.1021/nl025975r

Cited by 29 publications

(59 citation statements)

References 24 publications

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“…Details of the preparation of the hydrogen terminated Si(100)2×1 (Si(100)2×1-H) surface are described elsewhere [3]. The La 2 @C 80 , La@C 82 and La 2 @C 72 metallofullerenes were prepared by the DC arc discharge method and were isolated with high performance liquid chromatography [3,8].…”

Section: Methodsmentioning

confidence: 99%

“…Cage structures of the fullerenes and properties of encapsulated metal atoms of various endohedral metallofullerenes play important roles for determining the electronic properties of endohedral metallofullerenes. Scanning tunneling microscopy/spectroscopy (STM/STS) is a useful method to directly image the structures and electronic properties of fullerenes and endohedral metallofullerenes with an atomic resolution and a number of STM studies have previously been performed to characterize fullerenes on various surfaces [2][3][4][5][6][7]. In this letter, we report structures and electronic properties of La 2 @C 80 , La@C 82 and La 2 @C 72 molecules in monolayer and multi-layer islands grown on a hydrogen terminated Si(100)-2×1 surface by using an UHV-STM.…”

Section: Introductionmentioning

confidence: 99%

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UHV-STM/STS Studies of Endohedral La-Metallofullerenes on Hydrogen Terminated Si(100)2×1

Taninaka

Kato

Shino

et al. 2004

e-J. Surf. Sci. Nanotechnol.

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We have investigated monolayer and multilayer islands of La2@C80, La@C82 and La2@C72 grown on a hydrogenterminated Si(100)-2×1 surface by ultra-high-vacuum scanning tunneling microscopy/spectroscopy. The observed La2@C80 molecule has a spherical shape, consistent with a recent result by synchrotron X-ray measurements. The La2@C72 molecules are observed by STM as ellipsoids, consistent with a recent report by the 13 C-NMR structural analysis. The energy gap for the La2@C80 multilayer islands is measured to be 1.3-1.5 eV, whereas that for La@C82 is 0.5 eV, indicating that the Ih cage of the La2@C80 molecule is highly stabilized by an electron transfer from the encaged La atoms. The energy gap of the La2@C72 multi-layer islands is measured by STS as 1.0-1.2 eV, suggesting that the C72 carbon cage is stabilized by a localized electron transfer from the encaged La atoms to the fused-pentagon area of the fullerene cage.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

UHV-STM/STS Studies of Endohedral La-Metallofullerenes on Hydrogen Terminated Si(100)2×1

Taninaka

Kato

Shino

et al. 2004

e-J. Surf. Sci. Nanotechnol.

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“…Most of them require macroscopic quantities of metallofullerenes and give either ensemble averaged or spatially averaged results. It has been a challenging task to characterize the local properties of isolated metallofullerene molecules [8][9][10][11]. Here we show that scanning tunneling microscopy (STM) can be used to detect the encapsulated metal atom inside a fullerene cage.…”

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confidence: 99%

Unveiling Metal-Cage Hybrid States in a Single Endohedral Metallofullerene

et al. 2003

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The local structural and electronic properties of individual metallofullerenes are studied using scanning tunneling microscopy, scanning tunneling spectroscopy, and theoretical simulations. The energy-resolved metal-cage hybrid states of a single endohedral metallofullerene Dy@C 82 isomer I have been spatially mapped, supporting a complex picture consisting of the orbital hybridization and charge transfer for the interaction between the cage and the metal atom. The relative position of the encapsulated Dy atom inside the cage and the molecular orientation on the surface have been inferred by comparing the experimental results with theoretical simulations. The combined technique provides promising applications in the fields of in situ characterization and diagnostics of metallofullerene-based nanodevices. DOI: 10.1103/PhysRevLett.91.185504 PACS numbers: 61.48.+c, 31.15.Ew, 68.37.Ef, 73.22.-f Endohedral metallofullerenes have been a subject of intensive investigation in recent years, not only because of their structural and electronic novelties but also because of their promising electronic, optical, and biomedical applications [1]. The location of metal atoms inside the fullerene cage and the metal-cage interaction are two central issues. Various diffraction, spectroscopy, and microscopy techniques have been used to characterize metallofullerenes [2][3][4][5][6][7]. Most of them require macroscopic quantities of metallofullerenes and give either ensemble averaged or spatially averaged results. It has been a challenging task to characterize the local properties of isolated metallofullerene molecules [8][9][10][11]. Here we show that scanning tunneling microscopy (STM) can be used to detect the encapsulated metal atom inside a fullerene cage. The energy-resolved metal-cage hybrid states of a single endohedral metallofullerene Dy@C 82 isomer I have been spatially mapped using scanning tunneling spectroscopy (STS). Compared with other states of the metallofullerene, these hybrid states provide unique information on the location of metal atoms inside the fullerene cage and the metal-cage interaction. The relative position of the encapsulated Dy atom inside the cage and the molecular orientation on the surface have been inferred by comparing the experiments with theoretical simulations.The Dy@C 82 isomer I is a metallofullerene in which the Dy atom lies along a C 2 axis on the six-membered ring of the C 2v -C 82 cage [6]. Details for the preparation and separation of Dy@C 82 isomer I were described elsewhere [12,13]. A small amount of solid powder of Dy@C 82 was obtained in a crucible by evaporation of solvent in a dry box. The experiments were conducted in an ultrahigh vacuum STM chamber with a base pressure of 3 10 ÿ11 Torr. We first evaporated one monolayer Ag onto a Si(111) surface to form a 3 p 3 p -Ag surface and then a submonolayer of Dy@C 82 molecules was deposited on the Ag surface. All STM and STS measurements were performed at 5 K using an OMICRON cryostat GmbH STM with W tips that had been subject to ca...

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“…It was found that the Tb@C 82 molecules were randomly distributed on the surface of Si(100) but form a close-packing monolayer on the C 60 film. However, on a hydrogen-terminated Si(100)-2 × 1 surface, Shinohara et al found in the UHV-STM images that La@C 82 molecules in the multilayer show the ordered hexagonal close-packing array although La@C 82 molecules in the monolayer show an disordered adalyer on the surface [20].…”

Section: Introductionmentioning

confidence: 99%

“…Fullerenes with metal atoms encapsulated (endohedral metallofullerenes) are novel forms of fullerene-based materials [18][19][20]. Shi et al investigated Tb@C 82 molecules adsorbed on Si(100) 2 × 1 surface and the C 60 film with an ultrahigh vacuum scanning tunneling microscope (UHV-STM) [18].…”

Section: Introductionmentioning

confidence: 99%

ECSTM study of adsorption of C60, C70, C86 and Y@C82 on Au(111)

Jia

Gan

et al. 2010

Sci. China Chem.

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The adsorption of a variety of fullerenes (C 60 , C 70 , C 86 , Y@C 82 ) on Au(111) electrode surfaces was comprehensively investigated in 0.1 M HClO 4 by electrochemical scanning tunneling microscopy (ECSTM). In the ordered C 60 's adlayer, C 60 molecules formed either (2 3 2 3)  or "in-phase" structure. The high resolution STM image shows that the C 60 cage is not simply round but shows a bifurcated feature. The adsorption orientation of C 60 on Au (111) is tentatively suggested. In the ordered C 70 's adlayer, the perpendicular fullerene molecules are the main adsorption mode and form (2 3 2 3)  structure. However, for C 86 and Y@C 82 , the ordered adlayer could not be obtained on Au(111) under the present condition. These differences may be due to the different molecular shapes and sizes, and the encapsulated metal atom which affects the lattice matches with the substrate. The adsorption of fullerene molecules on Au(111) from disorder to order could be tuned simply by steering the dimensional sizes or shapes of the fullerenes used.

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Scanning Tunneling Microscopy/Spectroscopy Studies of Lanthanum Endohedral Metallofullerenes

Cited by 29 publications

References 24 publications

UHV-STM/STS Studies of Endohedral La-Metallofullerenes on Hydrogen Terminated Si(100)2×1

UHV-STM/STS Studies of Endohedral La-Metallofullerenes on Hydrogen Terminated Si(100)2×1

Unveiling Metal-Cage Hybrid States in a Single Endohedral Metallofullerene

ECSTM study of adsorption of C60, C70, C86 and Y@C82 on Au(111)

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