2,004 research outputs found
Fabrication of stable Pd nanowire assisted by hydrogen in solution
We have mechanically fabricated a Pd nanowire in solution under
electrochemical potential control. A clear feature appeared in the conductance
histogram when the electrochemical potential of the Pd wire was kept at the
hydrogen evolution potential. Conductance traces showed the Pd wire was
stretched 0.4 nm in length just before breaking, suggesting that at least two
Pd atoms might contribute to the formation of the Pd wire. The results indicate
that a certain atomic configuration of the Pd nanowire is stabilized by
hydrogen. We discuss the stabilization mechanism due to changes in bond
strengths caused by hydrogen adsorption or incorporation.Comment: 4 pages, 3 figures, Appl. Phys. Lett., in pres
Atomic Motion in Single H and D Molecule Junction Induced by Phonon Excitation
We have investigated Au atomic contacts in H and D environment by
conductance measurement and spectroscopy. A single H or D
molecule was found to bridge Au electrodes. In the case of the Au/H/Au
junction, symmetric peaks were observed in spectra, while they were not
observed for the Au/D/Au junction. The shape of the peaks in
spectra originated from the structural change of the single molecule junction
induced by the phonon excitation. The structural change could occur only for
the Au/H/Au junction. The difference in the two single molecule junctions
could be explained by larger zero point energy of Au-H vibration mode
than that in the Au/H/Au junction.Comment: 5 pages, 4 figures, to be appear in Phys. Rev.
Electric Conductance of Rh Atomic Contacts under Electrochemical Potential Control
The electric conductance of Rh atomic contacts was investigated under the
electrochemical potential control. The conductance histogram of Rh atomic
contacts varied with the electrochemical potential. When the electrochemical
potential of the contact was kept at = 0.1 V vs. Ag/AgCl (Rh
potential), the conductance histogram did not show any features. At =
-0.1 V (under potential deposited hydrogen potential), the conductance
histogram showed a feature around 2.3 ( =2), which
agreed with the conductance value of a clean Rh atomic contact, which was
observed in ultrahigh vacuum at low temperature. At = -0.25 V (over
potential deposited hydrogen potential), the conductance histogram showed
features around 0.3 and 1.0 . The conductance behavior of the Rh atomic
contact was discussed by comparing previously reported results of other metals,
Au, Ag, Cu, Pt, Pd, Ni, Co, and Fe. The conductance behavior of the metal
atomic contacts related with the strength of the interaction between hydrogen
and metal surface.Comment: 5 pages, 4 figures, Phys. Rev. B, in press
Hydrogen-assisted stabilization of Ni nanowires in solution
We have studied conductance characteristics of mechanically fabricated Ni
nanoconstrictions under controlling electrochemical potential and pH of the
electrolyte. Conductance histogram showed clear feature peaked at 1-1.5
(=) when the potential of the constriction was kept at more negative
potential than -900 mV vs. Ag/AgCl in pH=3.7. Comparable feature also appeared
at more positive potential when lower pH solution was used. We have revealed
that Ni mono atomic contact or mono atomic wire can be stabilized in solution
at room temperature under the hydrogen evolution.Comment: 4 pages, 3 figures; to appear in Appl. Phys. Let
Simulating a Simple Real Business Cycle Model Using Excel
Simulating the real business cycle models is a popular topic in first-year graduate courses on macroeconomics. Usually, Maple and Matlab are used for this purpose, mainly because they can be used both for solving and for simulating the models. Strulik (2004) demonstrates that Excel can be used both for solving and for simulating a standard RBC model. In this paper, we propose a more elementary approach that might be suitable for undergraduate courses. We illustrate (i) how to solve a simple RBC model by hand and (ii) how to use Excel to simulate the solution.
Conductance of a single molecule anchored by an isocyanide substituent to gold electrodes
The effect of anchoring group on the electrical conductance of a single
molecule bridging two Au electrodes was studied using di-substituted
(isocyanide (CN-), thiol (S-) or cyanide (NC-)) benzene. The conductance of a
single Au/1,4-diisocyanobenzene/Au junction anchored by isocyanide via a C atom
(junction with the Au-CN bond) was (). The
value was comparable to of a single
Au/1,4-benzenedithiol/Au junction with the Au-S bond. The
Au/1,4-dicyanobenzene/Au molecular junction with the Au-NC bond did not show
well-defined conductance values. The metal-molecule bond strength was estimated
by the distance over which the molecular junction was stretched before
breakdown. The stretched length of the molecular junction with the Au-CN bond
was comparable to that of the Au junction, indicating that the Au-CN bond was
stronger than the Au-Au bond.Comment: 3 figures, to be appear in Appl. Phys. Let
Three reversible states controlled on a gold monoatomic contact by the electrochemical potential
Conductance of an Au mono atomic contact was investigated under the
electrochemical potential control. The Au contact showed three different
behaviors depending on the potential: 1 ( = ), 0.5
and not-well defined values below 1 were shown when the
potential of the contact was kept at -0.6 V (double layer potential), -1.0 V
(hydrogen evolution potential), and 0.8 V (oxide formation potential) versus
Ag/AgCl in 0.1 M NaSO solution, respectively. These three
reversible states and their respective conductances could be fully controlled
by the electrochemical potential. These changes in the conductance values are
discussed based on the proposed structure models of hydrogen adsorbed and
oxygen incorporated on an Au mono atomic contact.Comment: 8 pages, 4 figures, to be appeared in Physical Review
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