Superparamagnetic microbeads play an important role in a number of scientific and biotechnology applications including single-molecule force measurements, affinity separation, and in vivo and in vitro diagnostics. Magneto-optically active nanorods composed of single-crystalline Au and polycrystalline Fe segments were synthesized with diameters of 60 or 295 nm using templated electrodeposition. The Fe section was magnetically soft and had a saturation magnetization of approximately 200 emu/g, resulting in a 10-fold increase in magnetization relative to that iron oxide nanoparticles. The strong plasmonic response of the Au segment of the rod in both the longitudinal and transverse directions made it possible to detect the orientation of a single rod in a polarized light microscope with nanometer resolution. These nanorods provide significantly improved physical properties over iron oxide superparamagnetic beads, making it possible to simultaneously manipulate and monitor the orientation of biomolecules with well-defined forces at the nanometer scale.

Two powerful synchrotron x-ray scattering techniques for residual strain depth-profiling and tomography-like scatter-intensity profiling of materials are presented. The techniques utilize energy dispersive x-ray scattering, from a fixed microvolume, with microscanning of the specimen being used to profile its interior. The tomography-like profiles exploit scattering-cross-section variations, and can be contrast enhanced by separately monitoring scattering from different crystal structures. The strain profiling technique is shown to finely chronicle the internal strain variation over several mm of steel. Detailed strain profiling for a cantilever spring demonstrates the interplay of residual and external stresses in elastic/plastic deformation. Since surface compression, by shot peening, is a classic method to fortify against fatigue failure, the strain profile for a shot-peened, surface-toughened material is determined and discussed in terms of a simple elastic–plastic stress/strain model. Finally the lattice strains in a WC/Co coated steel composite material are discussed.

Vertical arrays of Pd nanowire electrodes with controllable and reproducible diameters and lengths are fabricated using a porous anodic alumina (PAA) template supported on a metallized Si substrate. The process described here employs a hydrogen plasma to penetrate the alumina pore barrier oxide prior to electrodeposition, enabling direct electrical contact with the back electrode metallization, thereby eliminating the need for electrochemical processing with high current or voltage pulsing that can lead to delamination or voiding. Electrical characteristics reveal Ohmic contact between the Pd nanowires and the underlying Ti conductive layer for samples with a range of pore diameters from 30to130nm. This process enables both the fabrication of vertical nanowire arrays on prefunctionalized substrates, as well as the in situ fabrication of contacts to semiconductor nanodevices using a thin-film nanowire array. The hydrogen plasma step is particularly well suited to the fabrication of carbon nanotube arrays in PAA by plasma-enhanced chemical vapor deposition.

A procedure to fabricate a highly ordered electrodeposited nanowire array in a porous anodic alumina template with nanowires of uniform length and exposed tips for establishing low‐resistance ohmic contacts has been demonstrated. In this work, contacts to Au nanowire arrays have been investigated as a model system. The structural, topographical and electrical characteristics of the nanowire array have been studied using field emission scanning electron microscopy and conductive atomic force microscopy. Measurements showed that an electrical contact between the conducting AFM probe and the exposed Au nanowire tips was initiated only after a force of 14.4 ± 2 nN was applied. The I –V characteristics were linear up to the maximum applied current density of 1.5 × 1012 A/m2, and the resistivity of the individual Au nanowires in the template was estimated to be between 1.4 and 7 times the resistivity of large grained bulk Au. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

A nanocapacitor with ultra high capacitance (718 ± 0.2 pF) has been fabricated using electro-deposited Au nanowires manipulated between two Au microelectrodes by the dielectrophoresis technique. A high dc resistance value (∼100 M ) and nonlinear current-voltage characteristics indicate the formation of a dielectric interface between the nanowires. From frequency dependent conductivity, it is seen that the interface exhibits a giant dielectric permittivity (ε ∼ 1.8 × 10 7 ), which shows no frequency dispersion over the range from 30 Hz to 1 MHz. The enhancement of this permittivity value is attributed to the formation of a disordered interface containing gold atoms disrupted from the surface of the Au nanowires.