Chair
Professor Dieter Fenske, University of Karlsruhe, Germany
TBC
Professor Hideo Hosono, Tokyo Institute of Technology, Japan
Carbon Nanostructures - Direct Synthesis and Counterintuitive Transport Properties
Professor Martin Jansen, Max Planck Institute for Solid State Research, Germany
Abstract
Carbon based nanostructures such as fullerenes, nanotubes and graphenes attract considerable attention because of their unique properties and potential applications. Despite great success in the total synthesis of many complex organic molecules, the rational construction of fullerenes, and nanotubes still remains challenging. The main task of direct synthesis is the controlled generation of the desired nanostructures by rational chemical methods. This approach is of practical interest for the production of individual higher fullerenes and nanotubes with defined chiralities, and thus specific physical properties. Our methodology is based on the synthesis of polycyclic aromatic hydrocarbons which already contain all necessary carbon atoms in appropriate positions. Subsequent intramolecular condensation leads to the desired nanostructures, the carbon connectivity of which is fully predefined by the precursor molecule. We demonstrate on the examples of C60 and the 6/6 SWCNT that fully selective synthesis of such carbon nanostructures has become feasible.
The ability of fullerenes to accept excess electrons, up to twelve in the case of C60, is among the most conspicuous aspects of their chemistry and physics. The series of compounds as formed with alkali metals, AxC60 (A= Na, K, Rb, Cs; x = 1-6), is particularly interesting. Since except for A6C60, the conduction bands are partly filled for all of them, they are expected to show metallic conductivity. Surprisingly, A2C60 and A4C60 are reported to be insulating, while A3C60 becomes superconducting at quite elevated transition temperatures. In the case of C602- one faces the so-called open-shell problem. The two added electrons partially occupy the lowest unoccupied molecular orbital (LUMO) of the neutral C60 which has tiu symmetry and is three-fold degenerate. Yet, no evidence for a magnetic state has been found for C602- compounds. A singulet ground state can only be achieved by a Jahn-Teller (J-T) distortion. However, structural evidence for such a J-T effect has so far escaped detection. By analysing bond length alternation patterns in a series of high precision crystal structure data sets of ionic fullerides C602-, we became aware of a systematic anisotropy of the bond alternation lowering the point symmetry to D3d. By theoretical calculations it has been shown that these patterns unequivocally determine a particular singulet state as the electronic ground state of the C602- ions. Thus experimental data and calculations clearly confirm the first manifestation of a static J-T deformation in bulk fullerides. Interestingly, at the example of a (C60 )- radical anion, we have been able to also trace the transition from static to dynamic J-T effect, by EPR spectroscopy and temperature dependent x-ray crystallography. Recently, also for C604-, which is electronically inverse to C602-, evidence for a singulet ground state has been obtained from STM investigations on K4C60 mono-layers.
These findings on C602- and C604- are also relevant for superconductivity in the A3C60 compounds. Here the C60-ions are three-fold negatively charged in the average, however, electron transport implies intermediary charges of –2 and –4. Superconductivity may arise from structural relaxations related to charge fluctuations away from –3, accompanied by distortional modes. In the C602- fullerides treated here, these structural relaxations were seen in a quasi-frozen form.
Finally, we have spotted orbital ordering in a C 60 radical monoanion anion salt, resulting in a counterintuitive anisotropy of the electronic conductivity.
Structure determined catalysis by electron states 2e-e2= in condensed metal-ammonia, layer cuprates and Prussian Turnball's Blue systems
Professor Jennie Acrivos, San Jose State University, USA
Abstract
Growth catalysis for layer superconductors and Prussian-Turnbull’s_Blue is described by their structure, HOMO_LUMO LCAO components, determined by resonance enhanced X-Ray diffraction and absorption (J Kmiec and B Shyam, XRD, XAS Synchrotron measurements at DOE_SLAC_SSRL) near the constituents X-Ray edge Ea, based on 19thC Davy and Weyl chemical activity: bonding by 2e-e2=, also Mott and Alexandrov polaronbi-polaron superconductivity: (Bi1.7Pb0.3:Sr2:Can-1:Cun:O2n+4+δ)2≡2s:2:n-1:n=4-19, n’=2,3 intergrowth by concentrated sun radiation melt synthesis catalysis (DD Gulamova, Sun_Institute_Tashkent), and Prussian_Turnbull’s_Blue B≡Fe4[Fe(CN)6]3•15H2O room temperature annealed films (SC Weaver, SJSU), is determined by a photon absorption:
|Cu/Fe:1s2_HOMO|Q0>+hE0,Qo|Cu/Fe:1s_LUMOl=1,/Rydbergl=1,|Q>E<,>Ea,
,at a Bragg orientation Q0, followed by relaxation in t<10-16s, and excited e*(E,p*), excess energy E and momentum p* that Compton scatter a 2nd photon with conservation of energy and momentum, and from neighbors at RM, before t>10-15s vibration thermodynamic equilibrium is reached. 2s:2:n-1:n=4-19 mutually enhanced reflections {Q0,Q*=Q0[1+E/E0cos(p*^Q0)]Eo,Qo,Eo-Ea<100eV,Ea=9keV}={(0016),(200)}n=2 and others identify the reactive sites orientation, and HOMO/LUMO/LCAO Cu:(3d2sp3hybrid):M bonds by the relaxation characteristic core energy, M=SrM2,3:E=270-280eV, CaL2,3:E=349-346eV, and OK:E=525-540eV. B films obtain Ea=7126eV, Fe=Fe coordination valence intermediate between K3Fe(NC)6 and K4Fe(CN)6), resonance absorption Ea-E0=86-10eV mutually enhanced {(10,0,0),(8,6,0),(10,0,2)} and others for excited B*:FCC a*=20.34Å, with charge/spin transfer HOMO/LUMO/LCAO involved in core excitation to anti-bonding LUMO Fe(3d2sp3hybrid):N states, identified by characteristic core relaxation energy NK:E=411-425eV.
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Professor Jennie Acrivos, San Jose State University, USA
Professor Jennie Acrivos, San Jose State University, USA
Juana (Jennie) Vivó ACRIVOS, Emeritus Professor of Chemistry, San José State University, San José CA95192; jacrivos@earthklink.net, juana.acrivos@sjsu.edu; born Juana Luisa¬ Adolfina Vivό Azpeitia, Habana, Cuba; DSc U de La Habana, PhD U Minnesota; married Andreas Acrivos; Stanford U, UC Berkeley postdoctoral; SJSU teacher-research mentor 1963 to present; Colloque Weyl: CW:I-VII participant; Co-Chair, NF Mott, AD Yoffe: NATO Advanced Study Institute: “Physics, Chemistry of Electrons in Condensed Matter”, 1984; research in magnetic resonance, X-ray absorption, and diffraction applied to condensed matter: low dimensional solids, metal ammonia systems, semiquinones, MgO impurity states; ab-initio MOTECC Hartree Fock computations; experience for Kavli participation: (i) publications in CW:I-VII proceedings, (ii) Physics, Chemistry and Humphrey Davy", Chemistry in Britain, 20, 145(1984), (iii) publications on metal in ammonia solutions, layer superconductors, intercalation chemistry, doublet and triplet state magnetic resonance, and X-Ray absorption, diffraction, e.g., Microchemical Journal 99, 239(2011); Phys. Lett. A 371, 469(2007); J. Phys. Chem. 88, 3740(1984); Chem. Scripta, 17, 185(1981); J. Chem. Phys. 86, 1780(1987); Mol. Cryst. Liq. Cryst., 284, 411(1996); Phys. Rev B 50, 13710(1994); J. Solid State Chemistry, 111, 343(1994); Philos. Mag. 38, 81(1978); Proc. Nat. Acad. Sci., USA, 72, 464(1975); Philos. Mag.24, 29(1971); J. Phys .C: Solid St. Phys., 4, L18(1971).
Chair
Professor Peter Edwards FRS, University of Oxford, UK
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Professor Peter Edwards FRS, University of Oxford, UK
Professor Peter Edwards FRS, University of Oxford, UK
Peter P Edwards is Professor and Head of Inorganic Chemistry at the University of Oxford. His research interests include metal-insulator transitions, high temperature superconductivity, metals in non-aqueous solvents, small metallic particles and energy materials, with a particular emphasis on new-generation, high-performance materials for hydrogen production and storage, CO2 activation and utilisation, inorganic semiconductor thin films for solar energy applications and advanced catalytic materials.
Following BSc and PhD degrees at Salford University, Edwards spent periods at Cornell (Fulbright Scholar and National Science Foundation Fellow)), Cambridge (Lecturer and Director of Studies in Chemistry, Jesus College), Birmingham (Professor of Chemistry, and of Materials), before assuming his present position at Oxford in 2003. He was elected Fellow of the Royal Society in 1996 and to the German Academy of Sciences in 2009.
He has been the recipient of the Corday-Morgan, Tilden and Liversidge Medals of the Royal Society of Chemistry, and the Hughes Medal of the Royal Society. In 2012 he is to present The Bakerian Prize Lecture of the Royal Society; the Society’s premier lecture in the physical sciences.
Selection of Publications:
- Turning Points in Solid-State, Materials and Surface Science. A Book in Celebration of the Life and work of Sir John Meurig Thomas, KDM Harris, PP Edwards, eds, Royal Society of Chemistry, London (2007)
- Turning carbon dioxide into fuel, Z Jiang, T Xiao, VL Kuznetsov, PP Edwards, Phil Trans R Soc A, 368, 3343-3364 (2010)
- ' ... a metal conducts and a non-metal doesn't', PP Edwards, MTJ Lodge, F Hensel, et al, Phil Trans R Soc A, 368, 1914, 941-965, (2010)
- Functional Materials for Sustainable Energy Technologies: Four Case Studies, VL Kuznetsov, PP Edwards, ChemSusChem, 3, 1, 44-58 (2010)
- A Molecular Perspective on Lithium-Ammonia Solutions, E Zurek, PP Edwards, R Hoffmann, Angewandte Chemie-International Edition, 48, 44, 8198-8232 (2009)
- Photo-catalytic conversion of oxygenated hydrocarbons to hydrogen over heteroatom-doped TiO2 catalysts, NJ Luo, Z Jiang, HH Shi, FH Cao, T Xiao, PP Edwards, Int Journal of Hydrogen Energy, 34, 1, 125-129 (2009)
- Water/oil microemulsion for the preparation of robust La-hexaaluminates for methane catalytic combustion, Z Jiang, Su Hao, T Xiao, PP Edwards, Chem, Comm, 22, 3225-3227 (2009)
- Metallic Oxygen, PP Edwards and F Hensel, ChemPhysChem., 3, 53-56 (2002)
- What, Why and When is a Metal?, PP Edwards in The New Chemistry, ed N Hall, Cambridge University Press, 85-114 (2000)
- Synthesis and Superconducting Properties of the Strontium Copper Oxyfluoride Sr2CuO2F2+, M Al-Mamouri, PP Edwards, C Greaves and M Slaski, Nature, 369, 382-384 (1994)