Surface Plasmon Resonances of Cu Nanowire Arrays

Surface plasmon resonances of arrays of parallel copper nanowires, embedded in ion track-etched polycarbonate membranes, were investigated by systematic changes of nanowires’ topology and arrays area density. The extinction spectra exhibit two peaks which are attributed to interband transitions of Cu bulk metal and to a dipolar surface plasmon resonance, respectively. The resonances were investigated as a function of wire diameter and length, mean distance between adjacent wires, and angle of incidence of the light field with respect to the long wire axis. The dipolar peak shifts to larger wavelengths with increasing diameter and length, and diminishing mean distance between adjacent wires. Additionally, the shape effect on the dipolar peak is investigated.

Guiding of Highly Charged Ions through PC Nanocapillaries

Angular distribution and current dependence of the transmitted ion fraction are investigated for 40 keV Xe7+ bombarding on polycarbonate (PC) nanocapillaries. By measuring the angular distribution of the transmitted ion fraction, a strong guiding efect is found in PC nanocapillaries. Furthermore, with increase of the incident current, a turning point of the transmitted ion fraction is found, which is explained qualitatively by the discharge capacity of the nanocapillaries.

Controlled synthesis and diameter-dependent optical properties of Cu nanowire arrays

Using electrochemical deposition, Cu nanowire arrays have been successfully fabricated by home-made polycarbonate ion-track templates. The diameters were well controlled by etching time of templates. The minimum diameter is 15 nm. The morphologies and structures were analyzed by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The wires prefer [1 1 0] growth direction due to H ions absorption. The optical properties of Cu nanowire arrays are studied by an ultraviolet/visible/near-infrared spectrophotometer. Two extinction peaks were observed in spectra. The optical mechanism is discussed based on surface plasmon resonance

Preparation and characterization of CdS nanotubes and nanowires by electrochemical synthesis in ion-track templates

CdS nanotubes and nanowires have been synthesized with controlled dimensions by means of template-electrodeposition method in etched ion-track membranes. The diameters of nanotubes and nanowires are between 20 and I 10 nm, and the lengths are up to tens of micrometers. X-ray diffraction (XRD) and selected area electron diffraction (SAED) pattern investigations demonstrate that CdS nanotubes and nanowires are polycrystalline in nature. The UV-vis absorption spectra of CdS nanotubes and nanowires embedded in polycarbonate (PC) membranes show that the absorption edges of PC films shift towards the shorter wavelength, with decreasing diameters of the deposited nanostructures. The results indicate that nanowires are formed from nanotubes by nanotube-stuffing-growth mechanism.

Preparation of silver nanowires in ion-track membranes

Polycarbonate (PC) membranes were irradiated with swift heavy ions and latent tracks were created along the ions' trajectories. Nanopores, diameters between 100 and 500 nm, were obtained after illuminating the membranes with UV light and etching in NaOH solution. Silver nanowires were produced in the etched ion-track membranes by electrochemical deposition. The morphology and crystallinity of the silver nanowires were studied by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). Under certain conditions (deposition voltage 25 mV, current density 1-2 mA.cm(-2), temperature 50 degrees C, electrolyte 0.1 mol.L-1 AgNO3), single-crystalline silver nanowires with preferred orientation along the [111] direction can be synthesized.

Electrochemical polymerization and characterization of polypyrrole nanowires and nanotubules

Polypyrrole nanostructure arrays, including simultaneously large quantities of nanowires and small quantities of partially filled nanotubules have been electrochemically synthesized in home-made etched ion-track polycarbonate (PC) templates. Diameter of the prepared nanostructures varies from 45 to 320 nm with their lengths up to 30 microns. Morphological studies of these nanostructures were performed by field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM) and Raman spectroscopy. While optical absorption properties were studied by ultraviolet-visible-near infrared spectrophotometry (UV-vis-NIR). It has been observed that the absorption maximum of polypyrrole shifts to the longer wavelength side as the diameter of these nanostructures (nanowires and nanotubules) increases. (C) 2010 Elsevier B.V. All rights reserved.

Effect of Crystallographic Texture on Magnetic Characteristics of Cobalt Nanowires

Cobalt nanowires with controlled diameters have been synthesized using electrochemical deposition in etched ion-track polycarbonate membranes. Structural characterization of these nanowires with diameter 70, 90, 120 nm and length 30 mu m was performed by scanning electron microscopy, high-resolution transmission electron microscopy, and X-ray diffraction techniques. The as-prepared wires show uniform diameter along the whole length and X-ray diffraction analysis reveals that [002] texture of these wires become more pronounced as diameter is reduced. Magnetic characterization of the nanowires shows a clear difference of squareness and coercivity between parallel and perpendicular orientations of the wires with respect to the applied field direction. In case of parallel applied field, the coercivity has been found to be decreasing with increasing diameter of the wires while in perpendicular case; the coercivity observes lower values for larger diameter. The results are explained by taking into account the magnetocrystalline and shape anisotropies with respect to the applied field and domain transformation mechanism when single domain limit is surpassed.

Segmented All-Platinum Nanowires with Controlled Morphology through Manipulation of the Local Electrolyte Distribution in Fluidic Nanochannels during Electrodeposition

Synthesis of segmented all-Pt nanowires is achieved by a template-assisted method. The combination of a suitably chosen electrolyte/template system with pulse-reverse electrodeposition allows the formation of well-defined segments linked to nanowires. Manipulation of the morphology is obtained by controlling the electrokinetie effects on the local electrolyte distribution inside the nanochannels during the nanowire growth process, allowing a deviation from the continuously cylindrical geometry given by the nanoporous template. The length of the segments can be adjusted as a function of the cathodic pulse duration. Applying constant pulses leads to segments with homogeneous shape and dimensions along most of the total wire length. X-ray diffraction demonstrates that the preferred crystallite orientation of the polycrystalline wires varies with the average segment length. The results are explained considering transitions in texture formation with increasing thickness of the electrodeposit. A mechanism of segment formation is proposed based on structural characterizations. Nanowires with controlled segmented morphology are of great technological importance, because of the possibility to precisely control their substructure as a means of tuning their electrical, thermal, and optical properties. The concept we present in this work for electrodeposited platinum and track-etched polycarbonate membranes can be applied to other selected materials as well as templates and constitutes a general method to controlled nanostructuring and synthesis of shape controlled nanostructures.

聚碳酸酯膜的高能Ar离子辐照效应研究

本文简要介绍了PC材料的基本属性、用途和聚合物辐照效应的发展现状，以及荷能离子与固体相互作用的基本理论。重点描述了在兰州重离子加速器上完成的1.4GeV Ar离子辐照PC膜实验和辐照样品的付里叶转换红外谱（FT-IR）、紫外、可见光谱（UV、VIS）、X-射线光电子谱（XPS）和电子自旋共振谱（ESR）分析。分析结果表明：高能Ar离子在PC膜中引起的的主要辐照效应是键的断裂和材料的降解，重要降解发生在能量沉积密度大于8.0 * 10~(22)eV/cm~3或者电子能损大于1.4keV/nm时。这也表明了材料中的自由基增多，可蚀刻性增大。随辐照剂量和电子能损的增大，材料逐渐碳化，同时有类苯环物质和炔基生成。炔基的生成有一个剂量阈值为5.5 * 10~(11)ions/cm~3，有一个电子能损阈值为0.61keV/nm。在紫外、可见谱中，380nm、450nm和500nm波长处的吸光度变化随电子能损按平方规律变化，随剂量按线性规律变化。

Aliphatic Poly(ester-carbonate)s Bearing Amino Groups and Its RGD Peptide Grafting

This article deals with (1) synthesis of novel cyclic carbonate monomer (2-oxo [1,3]dioxan-5-yl)carbamic acid benzyl ester (CAB) containing protected amino groups; (2) ring-opening copolymerization of the cyclic monomer with L-lactide (LA) to provide novel degradable poly(ester-carbonate)s with functional groups; (3) removal of the protective benzyloxycarbonyl (Cbz) groups by catalytic hydrogenation to afford the corresponding poly(ester-co-carbonate)s with free amino groups; (4) grafting of oligopeptide Gly-Arg-Gly-Asp-Ser-Tyr (GRGDSY, abbreviated as RGD) onto the copolymer pendant amino groups in the presence of 1,1'-carbonyldiimidazole (CDI).