562 research outputs found
From Nanofabrication to Self-fabrication – Tailored Chemistry for Control of Single Molecule Electronic Devices
Single molecule electronics is a field of research focused on the use of single molecules as electronics components. During the past 15 years the field has concentrated on development of test beds for measurements on single molecules. Bottom–up approaches to single molecule devices
are emerging as alternatives to the dominant top–down nanofabrication techniques. One example is solution-based self-assembly of a molecule enclosed by two gold nanorod electrodes. This article will discuss recent attempts to control the self-assembly process by the use of supramolecular
chemistry and how to tailor the electronic properties of a single molecule by chemical design
Spin-dependent observables in surrogate reactions
Observables emitted from various spin states in compound U nuclei are
investigated to validate usefulness of the surrogate reaction method. It was
found that energy spectrum of cascading -rays and their multiplicities,
spectrum of evaporated neutrons, and mass-distribution of fission fragments
show clear dependence on the spin of decaying nuclei. The present results
indicate that they can be used to infer populated spin distributions which
significantly affect the decay branching ratio of the compound system produced
by the surrogate reactions
Charge transport through image charged stabilized states in a single molecule single electron transistor device
The present paper gives an elaborate theoretical description of a new
molecular charge transport mechanism applying to a single molecule trapped
between two macroscopic electrodes in a solid state device. It is shown by a
Hubbard type model of the electronic and electrostatic interactions, that the
close proximity of metal electrodes may allow electrons to tunnel from the
electrode directly into a very localized image charge stabilized states on the
molecule. Due to this mechanism, an exceptionally large number of redox states
may be visited within an energy scale which would normally not allow the
molecular HOMO-LUMO gap to be transversed. With a reasonable set of parameters,
a good fit to recent experimental values may be obtained. The theoretical model
is furthermore used to search for the physical boundaries of this effect, and
it is found that a rather narrow geometrical space is available for the new
mechanism to be effective: In the specific case of oligophenylenevinylene
molecules recently explored in such devices several atoms in the terminal
benzene rings need to be at van der Waal's distance to the electrode in order
for the mechanism to be effective. The model predicts, that chemisorption of
the terminal benzene rings too gold electrodes will impede the image charge
effect very significantly because the molecule is pushed away from the
electrode by the covalent thiol-gold bond.Comment: 9 pages, 5 figue
The 3-Dimensional q-Deformed Harmonic Oscillator and Magic Numbers of Alkali Metal Clusters
Magic numbers predicted by a 3-dimensional q-deformed harmonic oscillator
with Uq(3) > SOq(3) symmetry are compared to experimental data for alkali metal
clusters, as well as to theoretical predictions of jellium models, Woods--Saxon
and wine bottle potentials, and to the classification scheme using the 3n+l
pseudo quantum number. The 3-dimensional q-deformed harmonic oscillator
correctly predicts all experimentally observed magic numbers up to 1500 (which
is the expected limit of validity for theories based on the filling of
electronic shells), thus indicating that Uq(3), which is a nonlinear extension
of the U(3) symmetry of the spherical (3-dimensional isotropic) harmonic
oscillator, is a good candidate for being the symmetry of systems of alkali
metal clusters.Comment: 13 pages, LaTe
Deterministic assembly of linear gold nanorod chains as a platform for nanoscale applications
We demonstrate a method to assemble gold nanorods highly deterministically into a chain formation by means of directed capillary assembly. This way we achieved straight chains consisting of end-to-end aligned gold nanorods assembled in one specific direction with well-controlled gaps of [similar]6 nm between the individual constituents. We determined the conditions for optimum quality and yield of nanorod chain assembly by investigating the influence of template dimensions and assembly temperature. In addition, we transferred the gold nanorod chains from the assembly template onto a Si/SiO2 target substrate, thus establishing a platform for a variety of nanoscale electronic and optical applications ranging from molecular electronics to optical and plasmonic devices. As a first example, electrical measurements are performed on contacted gold nanorod chains before and after their immersion in a solution of thiol end-capped oligophenylenevinylene molecules showing an increase in the conductance by three orders of magnitude, indicating molecular-mediated transport
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