In this work the surface of (4 0 0) p-type Si wafers is bombarded with 29 keV nitrogen ions at various ion beam fluency varied from 1016 to 1018 ions/cm2 and the results are investigated. Si3N4 film with orthorhombic structure is formed on silicon surface with cubic structure while the lattice parameter of the generated layer is not affected by change of nitrogen ion beam dose. RMS roughness of implanted samples increases by increasing the nitrogen dose, specially when the dose is more than 3×1017 ions/cm2. Surface resistivity of samples is increased by increasing the dose of ion beam. Although changes in the transmission of implanted samples does not differ very much in comparison with row sample but reflection of implanted samples decrease about 60% for the electromagnetic wave in the range of 200 to 1500 nm. Absorption coefficient of samples is obtained and the band gap energy of samples is calculated. It is observed that formation of defect levels changes the magnitude of band gap energy.

This experimental work deals with the exposition of Pinus Pinaster wood samples to a DBD afterglow. Electrical parameters like duty cycle and injected energy in the gas are being varied and the modifications induced by the afterglow on the wood are analysed by several macroscopic and microscopic ways like wettability, XPS analyses and also soaking tests of treated wood in a commercial fungicide solution. Soaking tests show that plasma treatment could enhance the absorption of fungicide into the wood. The wettability results point out that the plasma treatment can inflict on the wood different surface properties, making it hydrophilic or hydrophobic, when varying electrical parameters. XPS analyses reveal several chemical modifications like an increase of the O/C ratio and the presence of carboxyl groups on the surface after plasma treatments.

We report on the effect of thickness on the structural and electrical properties of permalloy thin films Ni81Fe19 (Py). Permalloy films were deposited onto Si(100) substrates at room temperature using a KrF (wavelength of 248 nm, pulse duration of 30 ns) excimer laser at a fluence of 3 J/cm2. The thickness ranges from 25 nm to 250 nm. The micrographs reveal the formation of irregular droplets with dimensions between 4.6 μm and 0.24 μm. We show that all samples presented a strong $ \langle 100 \rangle$ texture. The lattice constant (a) monotonously increases with increasing thickness. Also, we note that for thickness below 127 nm, the lattice constant (a) is lower than the bulk value, however, for thickness more than 127 nm, (a) is higher than $a_{\rm bulk} $ . The grain size increases from 30 nm to 54 nm as the thickness increases from 45 nm to 250 nm. The different contributions to the electrical resistivity are investigated as a function of the Py thickness.

We have studied the enhancement of radiative emission rate of CdSe/ZnS core-shell quantum dots on semi-continuous gold films which have been prepared by using sputtering technique. The photoluminescence intensity and the decay rate of CdSe/ZnS quantum dots are affected by the semi-continuous gold films. Both the photoluminescence intensity and the decay rate of the quantum dots are greatly enhanced by the semi-continuous gold films near the conductive percolation threshold and that are caused by the enhanced local electric field due to the surface plasmon resonance on the semi-continuous gold films.

PbS quantum dots (bare and silica coated) have been synthesized in PVA matrix with average size 10 nm and 9 nm. The capacitance-voltage (C − V) and current –voltage (I − V) response of both bare and coated quantum dots have been recorded in different frequency range (Hz–MHz). Both the samples show frequency dependent response except in case of C − V characteristics at MHz range. The I − V responses at low frequency range exhibit step like structures which could be attributed to 'Coulomb blockade'.

This paper presents an experimental analysis of the electrical and optical behaviour of positive point-plane corona discharges. The measurements of the instantaneous corona current and the current-voltage characteristics are used with the imagery analyses (CCD and streak camera) to determine the streamer properties such as the streamer morphology and velocity with the primary and secondary streamer developments. These analyses are performed first in synthetic air as a function of operating parameters such the applied voltage. Then the effect of gas mixtures (several proportions of N2, O2 with or without CO2) is analysed. When the gas concentration is varied the discharge morphology, the shape and amplitude of the corona current are significantly affected due to the variation of the gas electronegativity following its composition and concentration.

Successful structural reinforcement of polymer matrices by carbon nanotube has been broadly applied where significant improvement of mechanical properties was achieved at a low carbon nanotube loading rate. The notion of the mechanical properties of aligned composites are better than random ones has been proofed and demonstrated whereas the concept is not easy to implement through carbon nanotube polymer composites by the conventional techniques. Here, we introduce a novel practice to actively align and network the multi-wall carbon nanotubes (MWCNTs) in hot melting high density polyester (HDPE) matrix. In this process, MWCNTs were aligned via AC electric field which induced dipolar interactions among the nanotubes in a hot melting matrix and followed by immobilization by cooling curing matrix under continued application of the anisotropic electric field. In situ SEM verified the electrostatic stabilization of the MWCNTs in the dispersion while the orientation and agglomeration are caused by the dielectrophoretic force. Alignment of MWCNTs was controlled as a function of magnitude, frequency, and application time of the applied dielectrophoresis. In the present work, MWCNTs are not only aligned along the field, but also migrate laterally to form thickness. Eventually, the actively aligned MWCNTs would amplify the hardness and wear-resisting property.

Using electron energy loss spectroscopy in a 100 kV VG scanning transmission electron microscope we study nitrogen doped carbon nanotubes grown via electron cyclotron resonance (ECR) microwave plasma techniques. The process is controlled by direct current (dc) biasing the grid separating the ECR source and the substrate. We show that plasma induced sputtering of the ECR source wall (stainless steel) can lead to significant iron and chromium contamination of growth samples. We identify various Fe, Cr, Ni nitride phases, and propose a growth model based on nitridation-induced metal segregation of steel based FeCrN alloys. Trace Cr doping of nanotube catalysts appears a promising route for introducing large nitrogen concentrations into both single and multi-walled nanotubes and may accelerate nanotube growth rates.

We report single transverse and longitudinal mode operation of an all solid-state orange laser pumped at 821 nm. Oscillation at 607 nm by avalanche upconversion in Pr, Yb:BaY2F8 pumped by a Ti-Sapphire laser at 821 nm is obtained with a threshold as low as 570 mW. A maximum output power of 12 mW is obtained for a pump power of 2.5 W.

This paper deals with the optical study of a DBD plasma afterglow generated in nitrogen at atmospheric pressure. Spectroscopic analyses allow identifying active species of this afterglow like molecular species in different energy levels: N2, NO and N2O(1S).By using the NO titration method, the N and O(1S) densities have been estimated to be respectively, 5.9 × 1014 cm−3 and 2 × 1010 cm−3, in an afterglow guided in a quartz tube of 1 cm in diameter.

Single-walled carbon nanotubes can be used as electron sources in the process of field emission, and have great potential for practical application of the field emission display (FED) panels with large screen size. We fabricated a FED using the single-walled carbon nanotubes (SWNTs) as the cathode by the screen-printing process. Test showed that the SWNTs emitters exhibit excellent macroscopic emission properties. It has low turn-on voltage (2.7 V/μm) and high brightness, with a high current density of good uniformity and stability. It was observed that the field emission qualitatively follows the conventional Fowler–Nordheim (F–N) theory, and aging treatment played an important role in improving the image uniformity and stability. Compared to other complicated processes, the simple fabrication using screen-printing process seems to be advantageous for practical application.

Magnetic thin films of Co80Cr16Ta4 were sputtered onto identical CrMo seed-layers at –200 V bias and 3 different substrate temperatures (150, 200, and 250 °C). Energy-filtered transmission electron microscopy (EFTEM) was performed to analyze Cr levels at the grain boundaries as well as inside the grains. These quantitative Cr measurements were used to estimate the local values of magnetocrystalline anisotropy (K u ) and, together with grain size distributions, calculate the product of K u and the grain volume (K uV ), a quantity which is a measure of thermal stability. The results show that the coercivity as well as the fraction of stable grains increased with increasing substrate temperature. The increase in the fraction of stable grains is produced by the enhancement in the K u value due to Cr depletion of the grain interiors and the magnetic decoupling between the grains from Cr grain-boundary segregation.

It is difficult for brittle materials to acquire high machined surface quality as they have low fracture strength. But in the case of nanometric cutting technology, nanometer level machined surface is often acquired by means of ductile material remove mode. In order to investigate physical essence of ductile machining process, this paper carries out molecular dynamics (MD) analysis of nanometric cutting single crystal silicon. The result shows that huge hydrostatic pressure induced in the local area which lead to the silicon atom transform from classical diamond structure (α silicon) to metal structure (β silicon). At the same time, the stress concentration is avoided by uniformly distributed pressure in the cutting area. These two important factors together result in the ductile machining of silicon and then acquire super-smooth surface.

We report on the synthesis of our work on the analysis of active spectro-polarimetric imaging concept of real-world scenes. These synthesis extend from the investigation of depolarization mechanisms up to image analysis and processing. We show in particular that depolarization effects are wavelength dependent and strongly correlated with light absorption of materials. Multi-wavelength images of degree of polarization are recorded and analyzed, evidencing that the polarimetric image must be interpreted in conjunction with its counterpart intensity image in order to extract, the most relevant information from the scene. For real field operation, the noise characteristics of polarimetric images are also investigated under coherent laser illumination. The potential increase of target detection performance brought by properly processing the active polarimetric image is illustrated on a very low contrast scene.

Using ethanol as a solvent p-aminoazobenzene (p-AAZB), an organic nonlinear optical crystal having good optical quality was grown by slow evaporation solution technique. Structural and optical properties were studied by applying XRD and UV-Vis spectroscopy. The measurement of the second harmonic generation was performed using the fundamental Nd:YAG 10 ns laser beam with wavelength 1.064 μm. Dependence of the second order susceptibilities for the two principal second order susceptibility tensor components d 14 and d 25 with the simultaneously applied dc- and UV-laser fields were investigated and discussed.

Polypyrrole/ polyaniline (PPy/PAn) composite films have been prepared by direct electrochemical polymerization of pyrrole in an aqueous solution of PAn. Spectroscopic results demonstrated that the polyanion, PAn, was incorporated into the PPy matrix as a dopant. The composite films exhibited a higher thermal stability than that of pure PPy. Scanning electron microscopic images revealed that the composite film had smooth and compact morphology.

Polycrystalline, smooth, and hard thin films of TiN are successfully deposited on AISI-304 substrates using a 1.5 kJ Mather-type dense plasma focus device charged at 18 kV. The purpose of this study is to investigate the structural and mechanical properties of the TiN thin films in terms of ion dose and substrate position to establish the optimum deposition conditions. The films are analyzed using XRD, SEM, electron microprobe and micro-hardness testing. XRD confirms the deposition of a polycrystalline TiN thin film together with the emergence of an iron chromium nickel phase. The surface hardness-in comparison to the unexposed substrate-is found to increase up to 250% when a film is deposited using 30 focus shots at an axial distance of 6 cm. SEM micrographs show that the quality of the film is improved with an increasing number of focus shots. The constituent elements of the film are also confirmed by electron microprobe.

We have developed an alignment tool for optical lattices with arbitrary beam angles, allowing for optical potentials with a range of geometries and topographies. A calibration procedure has been introduced, giving a precision of 10 mrad in the chosen beam angle, and a high degree of flexibility. The tool has been tested in simplified experiments on the confinement and expansion of cold atoms in one-dimensional and two-dimensional optical lattices, and has proved to work well.

A diode-pumped GaAs-passively-Q-switched intracavity-frequency-doubled Nd:YVO4/YVO4 green laser with a MgO-PPLN is presented. The characteristics of the passively Q-switched green laser pulses have been investigated. At the maximum incident pump power of 5.19 W, the minimum green-light pulse width of 26.4 ns has been obtained at a repetition rate of 134 kHz. The rate equations are presented to simulate the process of the green laser, and the numerical solutions of the coupled rate equations accord with the experimental results.

This paper addresses a multiscale strategy for the prediction of anhysteretic magneto-elastic behavior and its application to the definition of a magneto-elastic constitutive law for Terfenol-D. The multiscale modeling is based on an energetic procedure at the single crystal scale. Localization and homogenization procedures are then applied to deduce the constitutive law of polycrystalline media from the behavior of the corresponding single crystal. The method is applied first to define the magneto-elastic behavior of single crystals, and the application to polycrystalline samples is then considered. Modeling results are compared to experimental data.