Direct observation of conductance fluctuations of a single-atom tunneling contact. - In: Physical review. Condensed matter and materials physics / American Physical Society. - College Park, Md. : APS, 1970-2015 , ISSN: 1550-235X , ZDB-ID: 1473011-X, ISSN 1550-235X, Bd. 81 (2010), 3, S. 035406, insges. 6 S.
Using a cryogenic scanning tunneling microscope, the dynamics of lateral translations of a single silver atom adsorbed on Ag(111) were investigated with a time resolution of 10 ns. Elevated tunneling currents passed through the tip close to the adsorbed atom induce sudden adsorption site changes, which are reflected by two-level fluctuations of the tunneling conductance. The voltage dependence of the fluctuation rate reveals different local heating of the adsorbed atom in different positions relative to the tip.
http://dx.doi.org/10.1103/PhysRevB.81.035406
Control of spin-polarized current in a scanning tunneling microscope by single-atom transfer. - In: Applied physics letters, ISSN 1077-3118, Bd. 96 (2010), 13, S. 132505, insges. 3 S.
The spin polarization of the tunneling current between a Cr-covered scanning tunneling microscope tip and a Fe-covered W(110) surface was controllably modified by transferring single Cr atoms from the tip to the surface. Reproducible reversal of the spin polarization enables the discrimination of magnetic from electronic properties without the need of an external magnetic field.
http://dx.doi.org/10.1063/1.3377917
Conductance of Ag atoms and clusters on Ag(111): spectroscopic and time-resolved data. - In: Physica status solidi. Basic solid state physics. - Weinheim : Wiley-VCH, [1971]- , ISSN: 1521-3951 , ZDB-ID: 1481096-7, ISSN 1521-3951, Bd. 247 (2010), 5, S. 1077-1086
The evolution of the electronic structure of linear atomic Ag chains on Ag(111) has been explored atom by atom using low-temperature scanning tunnelling microscopy and spectroscopy. Electronic states confined to the linear chains are well described within a particle-in-a-box model. The evolution of an unoccupied Ag monomer resonance during the synthesis of an Ag dimer reveals that the Ag-Ag interaction is predominantly direct owing to the large spatial extension of p wave functions of the adsorbed atoms. The hopping dynamics of a single Ag atom adsorbed on Ag(111) have been monitored by time-resolved two-level conductance fluctuations of the tunnel junctions. Effective temperatures of the junction and diffusion barrier heights in the presence of the tip were extracted from a voltage-dependent analysis of the fluctuation rate.
http://dx.doi.org/10.1002/pssb.200945485
Atomic-scale control of electron transport through single molecules. - In: Physical review letters, ISSN 1079-7114, Bd. 104 (2010), 17, 176802, insges. 4 S.
Tin-phthalocyanine molecules adsorbed on Ag(111) were contacted with the tip of a cryogenic scanning tunneling microscope. Orders-of-magnitude variations of the single-molecule junction conductance were achieved by controllably dehydrogenating the molecule and by modifying the atomic structure of the surface electrode. Nonequilibrium Greens function calculations reproduce the trend of the conductance and visualize the current flow through the junction, which is guided through molecule-electrode chemical bonds.
https://doi.org/10.1103/PhysRevLett.104.176802
Molecular nanocrystals on ultrathin NaCl films on Au(111). - In: Journal of the American Chemical Society, ISSN 1520-5126, Bd. 132 (2010), 36, S. 12546-12547
Direct comparison of SnPc growth on a metal and a nearly insulating surface was achieved by adsorption of SnPc on Au(111) partially covered with NaCl. While on Au(111), SnPc lies flat and grows in a Stranski-Krastanov mode; on NaCl, Volmer-Weber growth of three-dimensional molecular nanocrystals occurs. On NaCl, intermolecular interactions dominate over the molecule-NaCl coupling and result in a tilted adsorption configuration.
https://doi.org/10.1021/ja105110d
Coverage driven formation of homochiral domains of an achiral molecule on Au(111). - In: The journal of physical chemistry. Energy, materials, and catalysis / American Chemical Society. - Washington, DC : Soc., 2007- , ISSN: 1932-7455 , ZDB-ID: 2256522-X, ISSN 1932-7455, Bd. 114 (2010), 42, S. 18247-18251
Adsorption of achiral Ni-tetramethyl-tetraazaannulene on Au(111) leads to the assembly of chiral trimers, which serve as building blocks for larger chiral patterns. A racemic mixture is observed at low coverages. Beyond a critical coverage, extraordinarily large homochiral domains occur and cover entire substrate terraces. The chiral structures and the formation of homochiral domains are induced by steric interactions.
http://dx.doi.org/10.1021/jp106973p
Graphene on Ru(0001) : contact formation and chemical reactivity on the atomic scale. - In: Physical review letters, ISSN 1079-7114, Bd. 105 (2010), 23, 236101, insges. 4 S.
Graphene on Ru(0001) is contacted with Au tips of a cryogenic scanning tunneling microscope. The formation and conductance of single-atom contacts vary within the moiré unit cell. Density functional calculations reveal that elastic distortions of the graphene lattice occur at contact due to a selectively enhanced chemical reactivity of C atoms at hollow sites of Ru(0001). Concomitant quantum transport calculations indicate that the graphene-Ru distance determines the conductance variations.
https://doi.org/10.1103/PhysRevLett.105.236101
Kondo effect of a Co atom on Cu(111) in contact with an iron tip. - In: Physical review, ISSN 1550-235X, Bd. 82 (2010), 23, S. 233401, insges. 4 S.
Single Co atoms, which exhibit a Kondo effect on Cu(111), are contacted with Cu and Fe tips in a low-temperature scanning tunneling microscope. With Fe tips, the Kondo effect persists with the Abrikosov-Suhl resonance significantly broadened. In contrast, for Cu-covered W tips, the resonance width remains almost constant throughout the tunneling and contact ranges. The distinct changes in the line width are interpreted in terms of modifications of the Co d state occupation owing to hybridization with the tip apex atoms.
http://dx.doi.org/10.1103/PhysRevB.82.233401
Quantification of H2O2 concentrations in aqueous solutions by means of combined NMR and pH measurements. - In: Physical chemistry, chemical physics, ISSN 1463-9084, Bd. 12 (2010), 40, S. 13166-13173
http://dx.doi.org/10.1039/C0CP00330A
Relaxation in a natural soil : comparison of relaxometric imaging, T 1 - T 2 correlation and fast-field cycling NMR. - In: The open magnetic resonance journal, ISSN 1874-7698, (2010), 3, S. 57-62
http://dx.doi.org/10.2174/1874769801003010057