Mito Kanai

Nanoscale solid-state quantum computing

Most experts agree that it is too early to say how quantum computers will eventually be built, and several nanoscale solid–state schemes are being implemented in a range of materials. Nanofabricated quantum dots can be made in designer configurations, with established technology for controlling interactions and for reading out results. Epitaxial quantum dots can be grown in vertical arrays in semiconductors, and ultrafast optical techniques are available for controlling and measuring their excitations. Single–walled carbon nanotubes can be used for molecular self–assembly of endohedral fullerenes, which can embody quantum information in the electron spin. The challenges of individual addressing in such tiny structures could rapidly become intractable with increasing numbers of qubits, but these schemes are amenable to global addressing methods for computation.

Competing interactions of noble metals and fullerenes with the Si(111)7×7 surface

Synchrotron-based photoelectron spectroscopy (PES) has been used to investigate the interaction of atomic gold and silver with a covalently bound C60-monolayer adsorbed on Si(111)7×7. In contrast to the relatively benign interaction of silver with the C60/Si(111)7×7 surface, core-level photoemission data reveal a strong interaction of gold with the underlying silicon despite the presence of a chemisorbed fullerene monolayer. The Si 2p PES data exhibit dramatic changes consistent with the formation of a gold silicide, which is also evident from the corresponding Au 4f spectra. Valence band photoemission also reveals the absence of any density of states at the Fermi level following the adsorption of either metal, indicating a negligible transfer of electrons from the adsorbed metal to the C60 cage.

Ordering and interaction of molecules encapsulated in carbon nanotubes

Abstract A clear understanding of the interactions between the building blocks of self-assembled molecular materials is essential for rational design of functional nanostructures. Intermolecular interactions have been investigated for three different classes of fullerenes in single-walled carbon nanotubes (SWNTs); van der Waals molecule – molecule and molecule – SWNT interactions control the geometry of the molecular arrays inside nanotubes; electrostatic intermolecular forces influence the alignment of polar endohedral fullerenes M@C82; and hydrogen bonding between functionalised fullerenes has a significant effect on the selectivity of insertion of functionalised fullerenes into SWNTs.

Purification and Characterization of Cerium Endohedral fullerenes

Cerium is the most common lanthanide element with its valence state +3 or +4. Cerium endohedral fullerenes, including Ce@C82 and Ce2@C80, were purified and characterized by MALDI‐TOF mass spectrometry, UV‐Vis and 13C NMR spectroscopy.

Isolation, Spectroscopic Characterization and Study of Island Formation of Two Isomers of the Metallofullerene Nd@C82

a Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK b Nanomaterials Laboratory (NML), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan c Korea Research Institute of Standards and Science (KRISS), Korea d Centre for Materials Research, Queen Mary, University of London, Mile End Road, London, E1 4NS, UK e Center for Interdisciplinary Magnetic Resonance, National High Magnetic Field Laboratory at Florida State University, Tallahassee, FL 32310, USA f Clarendon Laboratory, Parks Road, Oxford, OX1 3PU, UK

Isolation and spectroscopic characterization of two isomers of the metallofullerene Nd@C82

For the first time, two types of the metallofullerene Nd@C82 have been isolated and characterized. HPLC was used to isolate Nd@C82(I, II). The two isomers were characterized by mass spectrometry and UV‐Vis‐NIR absorption spectroscopy. Nd@C82(I) was found to be similar in structure to the main isomer of other lanthanofullerenes such as La@C82, as was previously reported. We assign Nd@C82(I) to have a C2v cage symmetry. Nd@C82(II) showed a markedly different UV‐Vis‐NIR absorption spectrum to Nd@C82(I). Its spectrum is in good agreement with that of the minor isomer of metallofullerenes such as Pr@C82. We therefore assign Nd@C82(II) to have a Cs cage symmetry. In contrast to other metallofullerenes, both isomers appear to be equally abundant.

Inserting Fullerene Dimers into Carbon Nanotubes: Pushing the Boundaries of Molecular Self‐assembly

Carbon nanotubes can encapsulate several molecular species forming one‐dimensional crystals. Using previously reported methods we produced directly‐bonded, asymmetric C60‐C70 dimers and oxygen‐bridged dimers of the type C60‐O‐C60. We present here microscopic evidence of filling single‐walled carbon nanotubes (SWNTs) with the above fullerene dimers. The most important filling constraint is found to be the nanotube size. SWNTs with diameters around 1.6 nm incorporate dimers considerably more easily than SWNTs with smaller diameters. This kind of molecular self‐assembly opens up the potential for using nanotubes and fullerenes for nanodevices.

Tumbling Cerium Atoms Inside the Fullerene Cage: iCe2C80

After a brief review of the production and decay of Schwarzschild-like (4 + n)dimensional black holes in the framework of theories with Large Extra Dimensions, we proceed to derive the greybody factors and emission rates for scalars, fermions and gauge bosons on the brane. We present and discuss analytic and numerical methods for obtaining the above results, and demonstrate that both the amount and type of Hawking radiation emitted by the black hole can help us to determine the number of spacelike dimensions that exist in nature.We report the spectroscopic work of two Ce‐containing incar‐fullerenes, iCeC82 and iCe2C80. UV/Vis, IR, Raman, TOF‐MALDI and 13C NMR were employed to investigate the structural and electronic information of these two major isomers of Ce incar‐fullerenes. Tumbling motion of two Ce atoms inside the Ih‐C80 cage was confirmed and analysed by temperature‐dependant 13C NMR.