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A protocol is described for forming reconnectable sub-5 nm nanogaps in single ultralong (>100 μm) gold nanowires fabricated by lithographically patterned nanowire electrodeposition (LPNE). During an initial computer-controlled electromigration process, gold nanowires with a rectangular cross-section were transformed by the formation of a constriction at a single point along the 250 μm length of the nanowire, and within this constriction a nanogap of width <5 nm. After this initial nanogap formation, 42% (19 of 45) of the gaps could be reconnected by applying a voltage ramp, restoring the electrical resistance of the original nanowire to within 10%. The voltage threshold for nanogap reconnection was narrowly distributed across multiple wires and nanogaps and in the range from 2 to 3 V. Using voltage programming, it was possible to cycle between the open and closed states for some nanogaps more than 100 times. We propose that the mechanism for reconnection involves the field evaporation of gold, qualitatively as observed previously for metal transfer from the tip of a scanning tunneling microscope. [ABSTRACT FROM AUTHOR]

Reports on the preparation of metallic molybdenum nanowires by electrodeposition. Uniformity of the hemicylindrical wires; Correlation of the mean wire diameter to the square root of the electrolysis time; Similarity of the conductivity and resiliency of the embedded wires to those of bulk molybdenum.

We describe the fabrication of arrays of nanowires onglass inwhich a gold core nanowire is encapsulated within a hemicylindricalshell of manganese dioxide. Arrays of linear gold (Au) nanowires arefirst prepared on glass using the lithographically patterned nanowireelectrodeposition (LPNE) method. These Au nanowires have a rectangularcross-section with a width and height of ≈200 and 40 nm, respectively,and lengths in the 1 mm to 1 cm range. Au nanowires are then usedto deposit MnO2by potentiostatic electrooxidation fromMn2늉溶⨧, forming a conformal, hemicylindrical shellwith a controllable diameter ranging from 50 to 300 nm surroundingeach Au nanowire. This MnO2shell is δ-phase andmesoporous, as revealed by X-ray diffraction and Raman spectroscopy.Transmission electron microscopy (TEM) analysis reveals that the MnO2shell is mesoporous (mp-MnO2),consisting of a network of ≈2 nm fibrils. The specific capacitance, Csp, of arrays of gold:mp-MnO2nanowires is measured using cyclic voltammetry.For a mp-MnO2shell thickness of 68 ±3 nm, core:shell nanowires produce a Cspof 1020 ± 100 F/g at 5 mV/s and 450 ±70 F/g at 100 mV/s. The cycle stability of this Csp, however, is extremely limited inaqueous electrolyte, decaying by >90% in 100 scans, but after ovendrying and immersion in dry 1.0 M LiClO4, acetonitrile,dramatically improved cycle stability is achieved characterized bythe absence of Cspfadefor 1000 cycles at 100 mV/s. Core:shellnanowires exhibit true hybridenergy storage, as revealed by deconvolution of Cspinto insertion and noninsertion components. [ABSTRACT FROM AUTHOR]

Parallel arrays of either Au or Pd nanowires were fabricated on glass substrates via the electrochemical process of lithographically patterned nanowire electrodeposition (LPNE) and then characterized with scanning electron microscopy (SEM) and a series of optical dithaction measurements at 633 nm. Nanowires with widths varying from 25 to 150 tim were electrodeposited onto nanoscale Ni surfaces created by the undercut etching of a photoresist pattern on a planar substrate. With the use of a simple transmission grating geometry, up to 60 diffraction orders were observed from the nanowire gratings, with separate oscillatory intensity patterns appearing in the even and odd diffraction orders. The presence of these intensity oscillations is attributed to the LPNE array fabrication process, which creates arrays with alternating interwire spacings of distances Δ+A and d -Δ, where d =25 μm and the asymmetry Δ varied from 0 to 3.5 μm. The amount of asymmetry could be controlled by varying the LPNE undercut etching time during the creation of the nanoscale Ni surfaces. The Fourier transform of a mathematical model of the nanowire array was used to predict the diffraction intensity patterns and quantitatively determine A for any grating. Additional sensitivity and an expanded dithaction order range were obtained through the use of external reflection (ER) and total internal reflection (TIR) diffraction geometries. [ABSTRACT FROM AUTHOR]