55 research outputs found
Tuning the electrical conductance of metalloporphyrin supramolecular wires
In contrast with conventional single-molecule junctions, in which the current flows parallel to the long axis or plane of a molecule, we investigate the transport properties of M(II)-5,15-diphenylporphyrin (M-DPP) single-molecule junctions (M=Co, Ni, Cu, or Zn divalent metal ions), in which the current flows perpendicular to the plane of the porphyrin. Novel STM-based conductance measurements combined with quantum transport calculations demonstrate that current-perpendicular-to-the-plane (CPP) junctions have three-orders-of-magnitude higher electrical conductanc than their current in-plane (CIP) counterparts, ranging from 2.10−2 G0 for Ni-DPP up to 8.10−2 G0 for Zn-DPP. The metal ion in the center of the DPP skeletons is strongly coordinated with the nitrogens of the pyridyl coated electrodes, with a binding energy that is sensitive to the choice of metal ion. We find that the binding energies of Zn-DPP and Co-DPP are significantly higher than those of Ni-DPP and Cu-DPP. Therefore when combined with its higher conductance, we identify Zn-DPP as the favoured candidate for high conductance CPP single-molecule devices
Study of the neoclassical radial electric field of the TJ-II flexible heliac
Calculations of the monoenergetic radial diffusion coefficients are presented
for several configurations of the TJ-II stellarator usually explored in
operation. The neoclassical radial fluxes and the ambipolar electric field for
the standard configuration are then studied for three different collisionality
regimes, obtaining precise results in all cases
Einfache Feldfunktionenreihen zur Nachbildung beliebiger singularitätenfreier Vakuumfelder in torusförmigen Gebieten in Reduce- und Fortran-Darstellung. - Simple Series of Harmonic Functions for Representing Arbitrary, Nonsingular Vacuum Fields in Toroidal Regimes in Reduce and Fortran Representation
Solution to Stellarator Boundary Value Problems with a New Set of Simple Toroidal Harmonic Functions
Stabilitätsverhalten kollektiver Elektronen-Ionen Dipol-Schwingungen im Elektronenring-Beschleuniger bei endlichen Feldindices, in Abhängigkeit vom azimutalen Magnetfeld
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