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Al Ma'Mari F, Rogers M, Alghamdi S, Moorsom T, Lee S, Prokscha T, Luetkens H, Valvidares M, Teobaldi G, Flokstra M, Stewart R, Gargiani P, Ali M, Burnell G, Hickey BJ, Cespedes O. Emergent magnetism at transition-metal-nanocarbon interfaces. Proc Natl Acad Sci U S A 2017; 114:5583-5588. [PMID: 28507160 PMCID: PMC5465901 DOI: 10.1073/pnas.1620216114] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Charge transfer at metallo-molecular interfaces may be used to design multifunctional hybrids with an emergent magnetization that may offer an eco-friendly and tunable alternative to conventional magnets and devices. Here, we investigate the origin of the magnetism arising at these interfaces by using different techniques to probe 3d and 5d metal films such as Sc, Mn, Cu, and Pt in contact with fullerenes and rf-sputtered carbon layers. These systems exhibit small anisotropy and coercivity together with a high Curie point. Low-energy muon spin spectroscopy in Cu and Sc-C60 multilayers show a quick spin depolarization and oscillations attributed to nonuniform local magnetic fields close to the metallo-carbon interface. The hybridization state of the carbon layers plays a crucial role, and we observe an increased magnetization as sp3 orbitals are annealed into sp2-π graphitic states in sputtered carbon/copper multilayers. X-ray magnetic circular dichroism (XMCD) measurements at the carbon K edge of C60 layers in contact with Sc films show spin polarization in the lowest unoccupied molecular orbital (LUMO) and higher π*-molecular levels, whereas the dichroism in the σ*-resonances is small or nonexistent. These results support the idea of an interaction mediated via charge transfer from the metal and dz-π hybridization. Thin-film carbon-based magnets may allow for the manipulation of spin ordering at metallic surfaces using electrooptical signals, with potential applications in computing, sensors, and other multifunctional magnetic devices.
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Affiliation(s)
- Fatma Al Ma'Mari
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom
- Department of Physics, Sultan Qaboos University, 123 Muscat, Oman
| | - Matthew Rogers
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Shoug Alghamdi
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Timothy Moorsom
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Stephen Lee
- School of Physics and Astronomy, Scottish Universities Physics Alliance, University of St. Andrews, St. Andrews KY16 9SS, United Kingdom
| | - Thomas Prokscha
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, 5232 Villigen, Switzerland
| | - Hubertus Luetkens
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, 5232 Villigen, Switzerland
| | | | - Gilberto Teobaldi
- Stephenson Institute for Renewable Energy, Department of Chemistry, University of Liverpool, Liverpool L69 3BX, United Kingdom
- Beijing Computational Science Research Centre, Beijing 100193 China
| | - Machiel Flokstra
- School of Physics and Astronomy, Scottish Universities Physics Alliance, University of St. Andrews, St. Andrews KY16 9SS, United Kingdom
| | - Rhea Stewart
- School of Physics and Astronomy, Scottish Universities Physics Alliance, University of St. Andrews, St. Andrews KY16 9SS, United Kingdom
| | | | - Mannan Ali
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Gavin Burnell
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - B J Hickey
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Oscar Cespedes
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom;
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Mamone S, Concistrè M, Heinmaa I, Carravetta M, Kuprov I, Wall G, Denning M, Lei X, Chen JYC, Li Y, Murata Y, Turro NJ, Levitt MH. Nuclear magnetic resonance of hydrogen molecules trapped inside C70 fullerene cages. Chemphyschem 2013; 14:3121-30. [PMID: 23788291 PMCID: PMC4068279 DOI: 10.1002/cphc.201300269] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Indexed: 11/29/2022]
Abstract
We present a solid-state NMR study of H2 molecules confined inside the cavity of C70 fullerene cages over a wide range of temperatures (300 K to 4 K). The proton NMR spectra are consistent with a model in which the dipole-dipole coupling between the ortho-H2 protons is averaged over the rotational/translational states of the confined quantum rotor, with an additional chemical shift anisotropy δ(H)(CSA)=10.1 ppm induced by the carbon cage. The magnitude of the chemical shift anisotropy is consistent with DFT estimates of the chemical shielding tensor field within the cage. The experimental NMR data indicate that the ground state of endohedral ortho-H2 in C70 is doubly degenerate and polarized transverse to the principal axis of the cage. The NMR spectra indicate significant magnetic alignment of the C70 long axes along the magnetic field, at temperatures below ~10 K.
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Affiliation(s)
- Salvatore Mamone
- School of Chemistry, Southampton University, Southampton SO17 1BJ (United Kingdom).
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Abstract
Hydrogen has a central role in the story of the universe itself and also in the story of our efforts to understand it. This paper retells the story of the part played by hydrogen and its stable isotope deuterium in the primordial synthesis of the elements, then goes on to describe how the spectrum of atomic hydrogen led to insights into the laws governing matter at the most fundamental level, from the quantum mechanics of Schrödinger and Heisenberg, through quantum electrodynamics, to the most recent work investigating the underlying structure of the proton itself. Atomic hydrogen is unique among the elements in that the concept of isotopy--atoms having the same nuclear charge but different masses--is stretched to its limit in the isotopes of hydrogen, ranging from the well-known isotopes deuterium and tritium to exotic species such as muonium, muonic helium, and positronium. These atoms, or atom-like objects, have much to tell us about fundamental aspects of the universe. In recent years the idea of utilizing hydrogen either as an energy source (through nuclear fusion) or as an energy storage medium (bound in hydrides or other materials) has attracted much attention as a possible avenue to a post-oil energy future. Some of the more interesting recent developments are described here. Dedicated to the memory of Brian C. Webster (1939-2008).
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Affiliation(s)
- Roderick M Macrae
- School of Mathematics and Sciences, Marian University, Indianapolis, Indiana 46222, USA.
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Päch M, Macrae RM, Carmichael I. Hydrogen and Deuterium Atoms in Octasilsesquioxanes: Experimental and Computational Studies. J Am Chem Soc 2006; 128:6111-25. [PMID: 16669680 DOI: 10.1021/ja055177d] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The rate of detrapping of atomic hydrogen from several octasilsesquioxanes is the same for dissolved and solid samples and is independent of the presence of other species such as free radicals or oxygen; varying the cage substituents leads to only minor differences in the activation parameters. Hydrogen atoms are found to be more strongly stabilized in homosubstituted octasilsesquioxanes compared with singly Ge-substituted cages. A kinetic isotope effect observed for the detrapping of H and D from MeT(8) is ascribed to the difference in the zero-point energies of the trapped atoms. There is a secondary H/D isotope effect in the temperature dependence of the (29)Si-superhyperfine splitting constants in the range 228-353 K. Cage relaxation has a substantial effect on the detrapping barrier but little influence on the intracage potential. Calculations using a rigid cage approximation give satisfactory agreement with zero-point parameters extracted from experimental data. Different model chemistries yield qualitatively different pictures of the dependence of the hyperfine coupling constant of the trapped H atom upon the detrapping coordinate. Within an isotropic approximation of the vibrational displacements, the B3LYP data give fairly close agreement with the experimental temperature dependence, subject to a shift of the absolute value related to known weaknesses of the method. For the Si(7)Ge cage, it is found that the transition state in which the H atom passes through a Ge-containing face is strongly favored, accounting for the larger detrapping rate parameters observed experimentally for this species.
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Affiliation(s)
- Michael Päch
- Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556, USA
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Gross B, Dilger H, Scheuermann R, Päch M, Roduner E. Electron Paramagnetic Resonance Study of the Dynamics of H and D Atoms Trapped in Substituted Silasesquioxane Cages. J Phys Chem A 2001. [DOI: 10.1021/jp012220k] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Barbara Gross
- Institute of Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany, and Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556
| | - Herbert Dilger
- Institute of Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany, and Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556
| | - Robert Scheuermann
- Institute of Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany, and Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556
| | - Michael Päch
- Institute of Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany, and Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556
| | - Emil Roduner
- Institute of Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany, and Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556
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Clipston NL, Brown T, Vasil‘ev YY, Barrow MP, Herzschuh R, Reuther U, Hirsch A, Drewello T. Laser-Induced Formation, Fragmentation, Coalescence, and Delayed Ionization of the C59N Heterofullerene. J Phys Chem A 2000. [DOI: 10.1021/jp001837j] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Nigel L. Clipston
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, England, U.K., Fachbereich Chemie, Universität Leipzig, Linnéstrasse 3, D-04103 Leipzig, Germany, and Institut für Organische Chemie, Universität Erlangen, Henkestrasse 42, D-91054 Erlangen
| | - Tracy Brown
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, England, U.K., Fachbereich Chemie, Universität Leipzig, Linnéstrasse 3, D-04103 Leipzig, Germany, and Institut für Organische Chemie, Universität Erlangen, Henkestrasse 42, D-91054 Erlangen
| | - Yury Y. Vasil‘ev
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, England, U.K., Fachbereich Chemie, Universität Leipzig, Linnéstrasse 3, D-04103 Leipzig, Germany, and Institut für Organische Chemie, Universität Erlangen, Henkestrasse 42, D-91054 Erlangen
| | - Mark P. Barrow
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, England, U.K., Fachbereich Chemie, Universität Leipzig, Linnéstrasse 3, D-04103 Leipzig, Germany, and Institut für Organische Chemie, Universität Erlangen, Henkestrasse 42, D-91054 Erlangen
| | - Rainer Herzschuh
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, England, U.K., Fachbereich Chemie, Universität Leipzig, Linnéstrasse 3, D-04103 Leipzig, Germany, and Institut für Organische Chemie, Universität Erlangen, Henkestrasse 42, D-91054 Erlangen
| | - Uwe Reuther
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, England, U.K., Fachbereich Chemie, Universität Leipzig, Linnéstrasse 3, D-04103 Leipzig, Germany, and Institut für Organische Chemie, Universität Erlangen, Henkestrasse 42, D-91054 Erlangen
| | - Andreas Hirsch
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, England, U.K., Fachbereich Chemie, Universität Leipzig, Linnéstrasse 3, D-04103 Leipzig, Germany, and Institut für Organische Chemie, Universität Erlangen, Henkestrasse 42, D-91054 Erlangen
| | - Thomas Drewello
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, England, U.K., Fachbereich Chemie, Universität Leipzig, Linnéstrasse 3, D-04103 Leipzig, Germany, and Institut für Organische Chemie, Universität Erlangen, Henkestrasse 42, D-91054 Erlangen
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Affiliation(s)
- Andreas Hirsch
- Institut für Organische Chemie der Universität Erlangen-Nürnberg, Henkestrasse 42, 91054 Erlangen, Germany
| | - Berthold Nuber
- Institut für Organische Chemie der Universität Erlangen-Nürnberg, Henkestrasse 42, 91054 Erlangen, Germany
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Cox SF. Muon spin relaxation studies of interstitial and molecular motion. SOLID STATE NUCLEAR MAGNETIC RESONANCE 1998; 11:103-121. [PMID: 9650794 DOI: 10.1016/s0926-2040(97)00100-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The unusual methods of preparation and analysis of spin polarization in muSR spectroscopy, which exploit the unique properties of the positive muon, are introduced in this article. Following a summary overview of applications, particular attention is paid to the problem of spin-lattice relaxation for a muon experiencing a hyperfine interaction with a single unpaired electron. The specific cases considered are the interstitial diffusion of muonium--the 1-electron atom which may be considered as a light isotope of hydrogen-and the molecular dynamics of organic radicals labelled by muonium. Rate equations for the evolution of population in the hyperfine-coupled spin states are solved numerically for various relaxation mechanisms. The formalism is equally valid for conventional ESR studies of paramagnetic states but is pursued specifically to simulate T1-relaxation in muSR. The simulations are compared with literature data. Also treated is the case of intermittent hyperfine coupling, appropriate to electron capture and loss in semiconductors or soliton motion in polymers; for this, a Monte Carlo approach is used to simulate the muon response. (For low-dimensional motion, the relaxation function is not exponential, so that a unique value of T1 cannot be defined.) Finally, a proposal is made to implement muon-T1 measurements in the rotating frame; this is designed for the selective study of electronically diamagnetic muonium states (i.e., those without hyperfine coupling) in the presence of a paramagnetic muonium or radical fraction.
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Affiliation(s)
- S F Cox
- ISIS Facility, Rutherford Appleton Laboratory, Chilton, Oxfordshire, UK
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Abstract
This paper contains a brief review of muon studies of organic conductors with emphasis on polymers. The species created by implanted muons in both semiconducting polymers and polymers doped to metallic values of conductivity are described. Both diamagnetic centres and paramagnetic radicals are formed in the semiconducting materials. The mechanisms of interaction of the muon with the polymers and the longitudinal relaxation of the muon species are discussed. In highly conducting polymers the muons are primarily present in diamagnetic states. Implanted muons have also been used to study both organic chargetransfer salts and Rb
3
C
60
in the superconducting state.
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Menon M, Richter E, Subbaswamy KR. Structural and vibrational properties of fullerenes and nanotubes in a nonorthogonal tight‐binding scheme. J Chem Phys 1996. [DOI: 10.1063/1.471319] [Citation(s) in RCA: 96] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Binninger U, Bernhard C, Hofer A, Niedermayer C, Recknagel E, Erxmeyer J, Weidinger A. Rotational dynamics of solid C70 investigated by the muon-spin-rotation technique. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 51:14867-14873. [PMID: 9978438 DOI: 10.1103/physrevb.51.14867] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Sachidanandam R, Lubensky TC, Harris AB. Phenomenologial dynamics of C70. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 51:12380-12397. [PMID: 9978007 DOI: 10.1103/physrevb.51.12380] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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McGhie AR, Fischer JE, Heiney PA, Stephens PW, Cappelletti RL, Neumann DA, Mueller WH, Mohn H. Phase transitions in solid C70: Supercooling, metastable phases, and impurity effect. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 49:12614-12618. [PMID: 10010164 DOI: 10.1103/physrevb.49.12614] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Christides C, John T, Dennis S, Prassides K, Cappelletti RL, Neumann DA, Copley JR. Rotational dynamics of solid C70: A neutron-scattering study. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 49:2897-2903. [PMID: 10011126 DOI: 10.1103/physrevb.49.2897] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Vaughan GB, Heiney PA, Cox DE, Fischer JE, McGhie AR, Smith AL, Strongin RM, Cichy MA, Smith AB. Structural phase transitions and orientational ordering in C70. Chem Phys 1993. [DOI: 10.1016/0301-0104(93)85096-q] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Tycko R, Dabbagh G, Vaughan GBM, Heiney PA, Strongin RM, Cichy MA, Smith AB. Molecular orientational dynamics in solid C70: Investigation by one‐ and two‐dimensional magic angle spinning nuclear magnetic resonance. J Chem Phys 1993. [DOI: 10.1063/1.465685] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Shin EJ, Park J, Lee M, Kim D, Doug Suh Y, Ik Yang S, Min Jin S, Keun Kim S. Temperature-dependent photoluminescence study of C60 and C70. Chem Phys Lett 1993. [DOI: 10.1016/0009-2614(93)80112-3] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Joslin C, Yang J, Gray C, Goldman S, Poll J. Infrared rotation and vibration—rotation bands of endohedral fullerene complexes. Absorption spectrum of Li+ @C60 in the range 1–1000 cm−1. Chem Phys Lett 1993. [DOI: 10.1016/0009-2614(93)80081-y] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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