Home About us Contact
|
Home About us Contact | ||
|
|
||
Nm Thickness (nm + thickness)
Selected AbstractsMultistep Anchoring Route of Luminescent (5-Amino-1,10-phenanthroline)tris(dibenzoylmethane)europium(III) on Si(100)EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 26 2010Guglielmo G. Condorelli Abstract A multistep route for the covalent anchoring of (5-amino-1,10-phenanthroline)tris(dibenzoylmethane)europium(III)molecules on silicon (100) has been developed. The anchoring route consists of Si functionalization with N -hydroxysuccinimide (NHS) activated carboxylic acid, followed by nucleophilic substitution at the carboxylic acid sites. Characterization of the resulting Si based hybrid materials was achieved by using several complementary techniques: X-ray photoelectron spectroscopy (XPS), attenuated total reflection FTIR spectroscopy (ATR-FTIR), AFM and fluorescence spectroscopy. Comparison of results obtained for NHS activated Si surfaces with those of inert alkyl functionalized Si surfaces proved the covalent anchoring of the Eu complex and ruled out the presence of physisorbed Eu species. The 1.8 nm thickness of the grafted layer, estimated by atomic-force lithography, is compatible with the presence of the anchored complex on the surface. Fluorescence measurements proved that luminescence properties are retained in the grafted complex. [source] Nitrided Amorphous Stainless Steel Coatings Deposited by Reactive Magnetron Sputtering from an Austenitic Stainless Steel TargetADVANCED ENGINEERING MATERIALS, Issue 1-2 2009Salvatore Cusenza Abstract Stainless steel films were reactively magnetron sputtered in argon/nitrogen gas flow onto oxidized silicon wafers using austenitic AISI 316 stainless-steel targets. The deposited films of about 300,nm thickness were characterized by conversion electron Mö-i;ssbauer spectroscopy, magneto-optical Kerr-effect, X-ray diffraction, Rutherford backscattering spectrometry, and resonant nuclear reaction analysis. These complementary methods were used for a detailed examination of the nitriding effects for the sputtered stainless-steel films. The formation of an amorphous and soft ferromagnetic phase in a wide range of the processing parameters was found. Further, the influence of postvacuum-annealing was examined by perturbed angular correlation to achieve a comprehensive understanding of the nitriding process and phase formation. The amorphous phase is not very stable and crystallization can be observed at 973,K. [source] Induced SER-Activity in Nanostructured Ag,Silica,Au Supports via Long-Range Plasmon CouplingADVANCED FUNCTIONAL MATERIALS, Issue 12 2010Jiu-Ju Feng Abstract A novel Ag,silica,Au hybrid device is developed that displays a long-range plasmon transfer of Ag to Au leading to enhanced Raman scattering of molecules largely separated from the optically excited Ag surface. A nanoscopically rough Ag surface is coated by a silica spacer of variable thickness from ,1 to 21,nm and a thin Au film of ,25,nm thickness. The outer Au surface is further functionalized by a self-assembled monolayer (SAM) for electrostatic binding of the heme protein cytochrome c (Cyt c) that serves as a Raman probe and model enzyme. High-quality surface-enhanced resonance Raman (SERR) spectra are obtained with 413,nm excitation, demonstrating that the enhancement results exclusively from excitation of Ag surface plasmons. The enhancement factor is estimated to be 2,×,104,8,×,103 for a separation of Cyt c from the Ag surface by 28,47,nm, corresponding to an attenuation of the enhancement by a factor of only 2,6 compared to Cyt c adsorbed directly on a SAM-coated Ag electrode. Upon immobilization of Cyt c on the functionalized Ag,silica,Au device, the native structure and redox properties are preserved as demonstrated by time- and potential-dependent SERR spectroscopy. [source] Adhesive, Flexible, and Robust Polysaccharide Nanosheets Integrated for Tissue-Defect RepairADVANCED FUNCTIONAL MATERIALS, Issue 16 2009Toshinori Fujie Abstract Recent developments in nanotechnology have led to a method for producing free-standing polymer nanosheets as a macromolecular organization. Compared with bulk films, the large aspect ratio of such nanosheets leads to unique physical properties, such as transparency, noncovalent adhesion, and high flexibility. Here, a biomedical application of polymer nanosheets consisting of biocompatible and biodegradable polysaccharides is reported. Micro-scratch and bulge tests indicate that the nanosheets with a thickness of tens of nanometers have sufficient physical adhesiveness and mechanical strength for clinical use. A nanosheet of 75,nm thickness, a critical load of 9.1,×,104,N m,1, and an elastic modulus of 9.6,GPa is used for the minimally invasive repair of a visceral pleural defect in beagle dogs without any pleural adhesion caused by wound repair. For the first time, clinical benefits of sheet-type nano-biomaterials based on molecular organization are demonstrated, suggesting that novel therapeutic tools for overlapping tissue wounds will be possible without the need for conventional surgical interventions. [source] Atomic Layer Deposition of UV-Absorbing ZnO Films on SiO2 and TiO2 Nanoparticles Using a Fluidized Bed Reactor,ADVANCED FUNCTIONAL MATERIALS, Issue 4 2008David M. King Atomic layer deposition (ALD) was used to apply conformal, nanothick ZnO coatings on particle substrates using a fluidized bed reactor. Diethylzinc (DEZ) and water were used as precursors at 177,°C. Observed growth rates were ca. 2.0 Å/cycle on primary particles as verified by HRTEM. ICP-AES and XPS were used to quantify Zn:substrate ratios. Layers of 6, 18, and 30 nm were deposited on 550 nm SiO2 spheres for UV blocking cosmetics particles. TiO2 nanoparticles were coated in the second part of this work by ZnO shells of 2, 5, and 10 nm thickness as novel inorganic sunscreen particles. The specific surface area of powders changed appropriately after nanothick film deposition using optimized conditions, signifying that high SA particles can be functionalized without agglomeration. The ZnO layers were polycrystalline as deposited and narrowing of the FWHM occurred upon annealing. Annealing the ZnO-TiO2 nanocomposite powder to 600,°C caused the formation of zinc titanate (Zn2TiO4) in both oxygen-rich and oxygen-deficient environments. The non-ideal surface behavior of the DEZ precursor became problematic for the much longer times required for high surface area nanoparticle processing and results in Zn-rich films at this growth temperature. In situ mass spectrometry provides process control capability to functionalize bulk quantities of nano- and ultrafine particles without significant precursor waste or process overruns. ZnO overlayers can be efficiently deposited on the surfaces of primary particles using ALD processing in a scalable fluidized bed reactor. [source] Super-resolution bright-field optical microscopy based on nanometer topographic contrastMICROSCOPY RESEARCH AND TECHNIQUE, Issue 4-5 2004Shu-Wei Huang Abstract By using an expectation-maximization maximum likelihood estimation algorithm to improve the lateral resolution of a recently developed non-interferometric wide-field optical profilometer, we obtain super-resolution bright-field optical images of nanometer features on a flat surface. The optical profilometer employs a 365-nm light source and an ordinary objective lens of a 0.95 numerical aperture. For objects of 100 nm thickness, lateral features about ,/7 can be resolved in the restored images without fluorescence labeling. Current image acquisition rate is 0.1 frame/sec, which is limited by the brightness of the light source. With a brighter light source, the imaging speed can be fast enough for real-time observation of dynamic activities in the nanometer scale. Microsc. Res. Tech. 65:180,185, 2004. © 2005 Wiley-Liss, Inc. [source] A comparative study of laser- and electric-field-induced effects on the crystallinity, surface morphology and plasmon resonance of indium and gold thin filmsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 4 2010Prashant Kumar Abstract The effects of post-deposition treatment of In and Au thin films by excimer laser and electric field are reported. The films were subjected to an electric field in the range of 0.1,3.3,kV/cm and laser irradiation in the range from 0.01 to 0.1,J/cm2. The effect of this treatment on the morphology and crystallinity of indium and gold thin films (10,100,nm thickness) is investigated. Indium films exhibited a three-fold grain growth at an electric field of 3.3,kV/cm. Gold thin film, on the other hand, showed significant grain growth at a much lower field of 0.6,kV/cm. The as-deposited thin films of indium and gold were amorphous but turned nanocrystalline with average crystallite sizes of 57,nm at 3.33,kV/cm and 35,nm at 0.66,kV/cm, respectively. When indium thin films were laser irradiated, flat disc-shaped grains for as-deposited thin films were transformed to spherical grains at a laser fluence of 0.02,J/cm2 and cubical grains at 0.05,J/cm2. At 0.05,J/cm2, as-deposited amorphous indium and gold thin films turned nanocrystalline with crystallite sizes of 50,nm and 10,nm, respectively. Significantly, laser treatment causes the grain-size distribution to become narrower with a shift in mean size to larger values. Electric-field treatment on the other hand leads to a shifting of the mean grain size to larger values without affecting the distribution. [source] Soft X-ray emission spectroscopy of low-dimensional SiO2/Si interfaces after Si+ ion implantation and ion beam mixingPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 3 2010D. A. Zatsepin Abstract An X-ray Si L2,3 -emission spectroscopy study of a SiO2/n-Si heterostructure containing a thin oxide layer of d,=,20,nm thickness implanted by Si+ ions with an energy 12,keV is reported. The maximum concentration of implanted Si+ ions is located close to the SiO2,Si interface at a depth of 18,nm leading to an ion-beam mixed SiO2/Si interface layer in this region, consisting of a non-stoichiometric SiOx matrix. The possible mechanisms of these processes are discussed by atomic collision cascades (knocking-off and knocking-on processes) during ion implantation, associated by partial phase separation into silicon precipitates and SiO2. [source] Growth and characterization of gallium oxide thin films by radiofrequency magnetron sputteringPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 8 2008P. Marie Abstract Undoped and Neodymium-doped gallium oxide (Ga2O3) thin films of about 500 nm thickness were successfully grown at different temperatures ranging from 100 up to 600 °C by radiofrequency magnetron sputtering. Post-annealing treatments were carried out at 900 °C and 1000 °C. The obtained films were (400) textured and a grain size of a few tens of nanometres was found. Optical and electrical characterizations led to a figure of merit of about 1.9 × 10,4. These films were successfully doped with Neodymium by a co-sputtering method. The photoluminescence experiments for the Nd-doped ,-Ga2O3 films clearly showed the rare-earth emitting signature. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Changes in optical properties of MnAs thin films on GaAs(001) induced by ,- to ,-phase transitionPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 4 2008B. Gallas Abstract MnAs layers with 45 nm thickness were grown epitaxially on GaAs(001) substrates. Ellipsometry measurements were made in the spectral range 0.045 eV to 6 eV as a function of temperature (between ,10 °C and 50 °C) at 70° of incidence. In this way the transition from the hexagonal ,-phase to the orthorhombic ,-phase could be monitored. Non-zero off-diagonal elements of the Jones matrix for an azimuth of 38° off the [10] axis of the substrate indicate that the optical functions of MnAs are anisotropic in both phases. The optical conductivity exhibits low-energy interband transitions around 0.3 eV, more clearly seen in the ,-phase than in the ,-phase. Extrapolation of the optical conductivity to zero frequency confirms that the ,-phase is about two times more conducting than the ,-phase. A broad structure is observed in the visible range around 3 eV. The ,-phase is characterised by an anisotropy induced energy difference of this structure with a maximum at 2.8 eV for the extraordinary index and at 3.15 eV for the ordinary index. This difference vanishes in the ,-phase in which anisotropy mainly induces changes in amplitude of the 3 eV structure. The assignment of the structures will be discussed. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] s-polarization Brewster's angle of stratified metal,dielectric metamaterial in optical regimePHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 12 2008Ryosuke Watanabe Abstract We demonstrate that the optical reflectivity for s-polarized light vanishes at a certain angle in a stratified metal,dielectric metamaterial numerically and experimentally. The metamaterial consists of a unit cell where a Ag layer of 30 nm thickness is sandwiched by Al2O3 layers of 60 nm thickness. In order to understand the phenomenon in terms of effective permittivity and permeability, we extended a field-sampling method. The permeability is found to be significantly different from unity, which is the origin of Brewster's angle for s-polarization. The microscopic field distribution is readily coarse grained with the effective optical parameters. The present result is a manifestation of the magnetic response in the optical regime. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Large enhancement of GaN-UV light emission using silver mirror resonatorPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2006N. M. Ahmed Abstract In this paper we used new microcavity resonator design of extracting light with high efficiency from a high index material (GaN), n > 2 for use in light emitting diode (LED) and laser diode (LD). A GaN/sapphire structure as an active layer was sandwiched between two silver mirrors. For the study two types of microcavity were fabricated: (air/GaN/sapphire/silver) and (silver/GaN/sapphire/silver). Via photo-luminescence measurements we observed 2-fold intensity enhancement in the UV region (364 nm) at room temperature by using 400 nm silver back mirror compared with uncoated sample. The amplitude of the photoluminescence is enhanced 10-times when we used 400 nm back coated together with 50 nm silver as front mirror. Further, a tremendous enhancement was obtained when a small hole was made in the front mirror with 50 nm thickness. The large increment of GaN/sapphire light emission in this microcavity could be caused by few important factors: increasing absorption in the cavity, optical field enhancement due to the resonator and coupling of plasmon in the metallic layer with the UV light. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Some properties of very thin Bi2Te3 layers prepared by laser ablationPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3 2003R. Zeipl Abstract Thin layers of Bi2Te3 60,nm thickness were prepared by laser ablation in vacuum using KrF excimer laser. The energy of laser varied from 300 to 680,mJ and the laser energy density from 2 to 10,J,cm,2. The substrate temperature varied for different depositions in the interval of 20,500,°C. The influence of preparation conditions on Hall mobility, concentration of charge carriers and conductivity at room temperature is presented. Information about morphology and composition of prepared layers is given. [source] Preparation and characteristics of nitrile rubber (NBR) nanocomposites based on organophilic layered clayPOLYMER INTERNATIONAL, Issue 7 2003Jin-tae Kim Abstract The effect of clay modification on organo-montmorillonite/NBR nanocomposites has been studied. Organo-montmorillonite/NBR nanocomposites were prepared through a melt intercalation process. NBR nanocomposites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic mechanical thermal analysis (DMTA) and a universal testing machine (UTM). XRD showed that the basal spacing in the clay increased, which means that the NBR matrix was intercalated in the clay layer galleries. On TEM images, organo-montmorillonite (MMT) particles were clearly observed, having been exfoliated into nanoscale layers of about 10,20 nm thickness from their original 40 µm particle size. These layers were uniformly dispersed in the NBR matrix. The DMTA test showed that for these nanocomposites the plateau modulus and glass transition temperature (Tg) increased with respect to the corresponding values of pure NBR (without clay). UTM test showed that the nanocomposites had superior mechanical properties, ie strength and modulus. These improved properties are due to the nanoscale effects and strong interactions between the NBR matrix and the clay interface. Copyright © 2003 Society of Chemical Industry [source] Preparation and mechanical properties of well-aligned and well-oriented poly(vinyl alcohol) nanoribbonPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 3 2009Mai Iwashita Abstract We report a novel, economical method of preparing well-aligned and well-oriented nanoribbons made of poly(vinyl alcohol) (PVA). The method requires no special equipment and easily produces nanoribbon. The structure of uniaxially drawn nanoribbon was investigated by polarized microscopy, polarized FT-IR, and X-ray diffraction, which showed high molecular and crystallite orientations. The well-aligned PVA nanoribbon, measuring several tens of micrometer width and around 400,nm thickness, had a Young's modulus of 9,GPa and a tensile strength of 350,MPa. Copyright © 2008 John Wiley & Sons, Ltd. [source] | |||||||||||||