Transport spin polarization of Ni_xFe_{1-x}: electronic kinematics and band structure
We present measurements of the transport spin polarization of Ni_xFe_{1-x} (0
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When Gold Is Not Noble: Nanoscale Gold Catalysts
While inert as bulk material, nanoscale gold particles dispersed on oxide supports exhibit a remarkable catalytic activity. Temperature-programmed reaction studies of the catalyzed combustion of CO on size-selected small monodispersed Au n ( n ≤ 20) gold clusters supported on magnesia, and first-principle simulations,…
Elaboration, characterization and aging effects of porous silicon microcavities formed on lightly p-type doped substrates
In this paper we present and discuss the realization and optical characterization of porous silicon microcavities formed on p - -type doped substrates. We produce porous silicon microcavities with a very narrow bandwidth (5.5 nm) and a good ratio of the peak to background emission, reaching at the same time a high emi…
Evolution of density fluctuations to lamellar crystals in linear polyethylene
Structure formation during the isothermal crystallization of a linear polyethylene (Mw=32 100 g/mol, Mw/Mn=1.1) has been monitored by simultaneous real time small-angle x-ray scattering (SAXS) and wide angle x-ray scattering (WAXS) with synchrotron radiation. Changes in the crystalline and amorphous scattering in WAXS…
T= 0 partition functions for Potts antiferromagnets on square lattice strips with (twisted) periodic boundary conditions
We present exact calculations of the zero-temperature partition function for the q -state Potts antiferromagnet (or, equivalently, the chromatic polynomial) for two families of arbitrarily long strip graphs of the square lattice with periodic boundary conditions in the transverse direction and (i) periodic and (ii) tw…
Selective-area and lateral overgrowth of chromium dioxide (CrO2) films by chemical vapor deposition
Selective-area growth has been utilized to deposit chromium dioxide (CrO2) films in specific regions of a prepatterned surface using atmospheric pressure chemical vapor deposition from CrO3 precursor. For films deposited on single crystal TiO2 substrates covered with patterned SiO2 thin film, epitaxial growth occurs s…
Energy levels in metal oxide semiconductor quantum dots in water-based colloids
The three-dimensional Schrödinger and Poisson’s equations are used to calculate the conduction band profile, energy levels, and Fermi energy of negatively charged semiconductor quantum dots. The calculation is carried out self-consistently within the frame of the finite-difference method. Assuming the effective mass o…
Molecular N2 chemisorption—specific adsorption on step defect sites on Pt surfaces
Infrared reflection-absorption spectroscopy and density functional theory, within the generalized gradient approximation, were used to investigate both experimentally and theoretically N2 chemisorption on stepped and smooth Pt surfaces. N2 chemisorption was observed to occur only on the edge atoms of step defect sites…
Synthesis and characterization of amorphous carbon nanowires
By heating a pressed tablet of graphite powder mixed with nickel in a quartz tube mounted inside a high-temperature tube furnace at 1200 °C, amorphous carbon nanowires were formed on the inner wall of the quartz tube near a copper cooling finger. Bright-field images of transmission electron microscopy show that the di…
Single-wall carbon nanotube circuits assembled with an atomic force microscope
We have developed a method to assemble single-wall carbon nanotube (SWNT) circuits using a tapping mode atomic force microscope. Nanotubes can be controllably translated, rotated, cut, and placed on top of one another by varying the tip–sample force, and the tip speed. These operations let us construct complex nanotub…
Nanometer-Scale Surface Patterns with Long-Range Order Created by Crystallization of Diblock Copolymers
We report experimental observations on the ordered surface patterns resulting from the crystallization of annealed thin films of microphase-separated low-molecular-weight hydrogenated poly(butadiene- $b$-ethyleneoxide) diblock copolymers. For crystal growth rates higher than about 1 nm $/$sec the resulting orientation…
Low-Cycle Fatigue of TiNi Shape Memory Alloy and Formulation of Fatigue Life
The low-cycle fatigue of a TiNi shape memory alloy was investigated by the rotating-bending fatigue tests in air, in water and in silicone oil. (1) The influence of corrosion fatigue in water does not appear in the region of low-cycle fatigue. (2) The temperature rise measured through an infrared thermograph during th…
Correlated Fermions in a One-Dimensional Quasiperiodic Potential
We study analytically one-dimensional interacting spinless fermions in a Fibonacci potential. We show that the effects of the quasiperiodic modulation are intermediate between those of a commensurate potential and a disordered one. The system exhibits a metal-insulator transition whose position depends both on the str…
In situ resistance measurements of strained carbon nanotubes
We investigate the response of multiwalled carbon nanotubes to mechanical strain applied with an atomic force microscope probe. We find in some samples, changes in the contact resistance dominate the measured resistance change. In others, strain large enough to fracture the tube can be applied without a significant ch…
Understanding Depletion Forces beyond Entropy
The effective interaction energy of a colloidal sphere in a suspension containing small amounts of nonionic polymers and a flat glass surface has been measured and calculated using total internal reflection microscopy and a novel approach within density functional theory, respectively. Quantitative agreement between e…
Dual Chemical Role of Ag as an Additive in Chalcogenide Glasses
Ternary $({\mathrm{Ge}}_{x}{\mathrm{Se}}_{1\ensuremath{-}x}{)}_{1\ensuremath{-}y}{\mathrm{Ag}}_{y}$ bulk glasses in the Se-rich region $(x<\frac{1}{3})$ are shown to be intrinsically phase separated into an ${\mathrm{Ag}}_{2}\mathrm{Se}$-rich glass and a residual ${\mathrm{Ge}}_{t}{\mathrm{Se}}_{1\ensuremath{-}t}$…
Giant magnetic-field-induced strains in Heusler alloy NiMnGa with modified composition
A giant magnetic-field-induced strain (MFIS) of −3100 ppm has been obtained in Heusler alloy Ni52Mn22.2Ga25.8 single crystal in the [001] direction at a temperature from 23 to 31 °C. This MFIS reaches saturation in an applied field about 6 kOe, and exhibits the same amplitude with an opposite sign while the field is p…
Field-emission characteristics of SiC nanowires prepared by chemical-vapor deposition
Silicon carbide (SiC) nanowires on a silicon substrate were prepared using hot-filament-assisted chemical-vapor deposition with a solid silicon and carbon source. The SiC nanowires show good field-emitting properties as revealed by the current–voltage characteristics. Together with its ease of preparation, these SiC n…
Diffuse Phase Transition and Phase Separation in Cr-DopedNd1/2Ca1/2MnO3: A Relaxor Ferromagnet
We have investigated the diffuse phase transition accompanying the formation of submicrometric ferromagnetic-metallic (FM) domains embedded in the antiferromagnetic charge-ordered state in ${\mathrm{Nd}}_{1/2}{\mathrm{Ca}}_{1/2}{\mathrm{MnO}}_{3}$ crystals, which is caused by quenched random field originating from Cr…
Viscoelasticity and generalized Stokes–Einstein relations of colloidal dispersions
The linear viscoelastic and diffusional properties of colloidal model dispersions are investigated and possible relations between the (dynamic) shear viscosity and various diffusion coefficients are analyzed. Results are presented for hard sphere and charge-stabilized dispersions with long-range screened Coulomb inter…