Effect of Substrate Temperature on the Structural and Morphological Properties of Nano-structure ZnO films by Pulsed Laser Deposition

In this work, ZnO thin films were grown on sapphire (0001) substrate by Pulsed Laser Deposition using SHG with Q-switched Nd:YAG pulsed laser operation at 532nm in O2 gas ambient 5×10-2 mbar at different substrate temperatures varying from room temperature to 500°C. The influence of the substrate temperature on the structural and morphological properties of the films were investigated using XRD and SEM. As result, at substrate 400°C, a good quality and crystalline films were deposited that exhibits an average grain size (XRD) of 22.42nm with an average grain size (SEM) of 21.31nm

Thin Films Ablation by Induced Forward Transfer Technique

Laser-Induced Forward Transfer (LIFT) is a technique which enables the controlled transfer of a thin film material from a transparent carrier (donor) to a receiver substrate (acceptor). The receiver substrate is usually placed in parallel and close to the thin film source under air or vacuum conditions. In this work microdeposition of gold (Au) and Copper (Cu) thin films were deposited on glass substrate by Pulsed Laser Deposition (PLD). These thin films were irradiated by a single pulse and transferred to a silver (Ag) and silicon (Si) receiver substrates. The laser source used for this study was a Nd-YAG Q-Switching second harmonic generation (SHG) Pulsed Laser with a wavelength 532nm, repetition rate 1-6 Hz ,and pulse duration 10ns. Deposited size, morphology and adhesion to the receiver substrate as a function of applied laser fluence are investigated

Preparation of NanostructureTiO2 at Different Temperatures by Pulsed Laser Deposition as Solar Cell

Deposition of the Titanium oxide (TiO2) particles on glass and the Si substrates was materialized for a wide range of temperatures (100-400)°C; using PLD technique at constant laser energy 800 mJ of frequency doubled Nd: YAG laser wavelength of 532nm running at 10 Hz rate and 10ns duration pulses. UV-Vis spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), X-ray fluorescence (XRF), Scanning Electron Microscopy (SEM), Atomic Force Microscope(AFM), electrical conductivity (σdc), Hall coefficient (RH) and (I-V) and (C-V) measurements were employed to examine optical, morphological and electrical properties of the deposited films. 85% film transparency was accomplished with optical band gap of (3.25 – 3.64) eV.(I-V) characteristics showedan enhanced TiO2 p-n junction thin film solar cell efficiency by 1.6% at 400°C

Effect of Aperture shape on Visibility of Quantum Cryptography System

The main goal in Quantum Cryptography is high security and this can be achieved by using single photon sources, thus we have studied the entangled photon source and how the coincident count rate and visibility could be affected by the optical elements of the system setup. The present work is a theoretical analysis devoted to investigate the interference pattern of biphoton amplitude generated by spontaneous parametric down conversion (SPDC) in a nonlinear crystal (BBO) pumped by femto-second optical pulses. We have studied the visibility as a function of optical path delay for different parameters, such as the crystal length, aperture diameter, size and shape of the aperture The shape of interference pattern can be enhanced by using different shapes & sizes of aperture. So in the case of continuous wave ( CW )pumping, when using circular aperture the visibility is highest and symmetry shape occurs at lower aperture diameter (b=0.5mm). Asymmetry and wide dip pattern is occurred at larger aperture diameter (b=10mm), when using shifting ring, a negative peak was appeared. In case of pulsed pump asymmetry, patterns occur and increase with increase of crystal length and decreasing aperture diameter. When using slit aperture (vertical and horizontal direction), the coincident count is more symmetric in horizontal with dimension (1x7) mm. All the results of this work are based on several numerical techniques and different programming codes. For example, adaptive Simpson quadrator method have been used to numerically evaluate the double integral in some equations. And adaptive Lobatto quadrator method has been used to numerically evaluate a single integrals. The later method is more efficient when required a high accuracy or a smooth integra

Functionalization and Characterization of Multi-Walled Carbon Nanotubes Using Chemical Oxidation Method

Functionalized MWNTs have been of interest for dispersion enhancement in processing or for chemical modifications. Modification of multiwall carbon nanotubes (MWNTs) by ultrasonication with oxidizing acid mixtures is frequently used to functionalize CNTs. In this work, the functionalization process of MWCNTs involves using a mixture of concentrated sulfuric acid and nitric acid (95% H2SO4: 65%HNO3, 3:1 volume ratio), ultrasonicated at 250C for 30min. The results confirmed by Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), and Scanning Electron Microscopy (SEM). From the FTIR spectrum, the existence of carboxyl group indicates the functionalization of MWCNTs on the outer surface wall. SEM micrographs show the occurrence of surface modification on the MWCNTs structure. Finally, a well dispersed of MWCNTs colloidal was successfully obtained with less MWCNTs structure collapsed

Electrochemical behavior and characterization of grafted polystyrene-acrylonitrile electrodes.

The redox of grafted polymer electrodes GPE (grafted polystyrene-acrylonitrile, GP15%, GP45% and GP50% grafting percentage) in aqueous electrolyte has been studied under various voltammetric conditions. In this work, voltammetric studies were carried out, principally in electrolyte containing potassium chloride. It was observed that GP15% has a good potential window at -2.0 - +2.0V without any current peak, while GP45% has reduction and oxidation current peaks at -175.9 and +210mV respectively. Also GP50% has oxidation and reduction current peaks at +263.1 and -261.9mV respectively. The redox process is irreversible in aqueous electrolyte containing different alkaline cations, such as Na+ , K+ , Rb+ and Cs+ . The shift of redox potential was found to follow the change in the hydration energy in the order: Cs+ >Rb+ > K+ >Na+ . In addition, the redox peaks of the fabricated electrodes from GP were also studied in aqueous electrolytes at different anaions (KCl, KClO4, K2HPO4, KNO3 and K2SO4), which gave good redox peaks in KCl and enhanced the redox current via increasing the concentration. Electrochemical experiments reveal that the grafted polymer electrodes show improved electron-transfer characteristics and exhibit high electrocatalytic activity for grafted percentage in the order of : 15% > 45% > 50%. The applications of these electrodes, especially type 15%, are in the cyclic voltammetric technique when used as a working electrode

Production of a Laccase from Botrytis cinerea (DSMZ 877) and Application for Textile Phenolic Dye Decolorization

AbstractIn this study, the production, partial purification and characterization of a laccase from Botrytis cinerea strain (DSMZ No. 877) was studied. The production of laccase was induced using copper sulphate and Gallic acid as inducers. The maximum laccase activity observed during B. cinerea growth in the presence of 0.1% Gallic acid was 2600 UL−1. Laccase purification was performed by precipitated the enzyme with 90% ammonium sulphate followed by gel filtration chromatography. The optimum pH for the laccase activity was observed at acidic pH values (close to pH 3.5 - 4.6), while the optimum temperature was 70°C. The ability of the produced laccase as well as the laccase from T. versicolor to catalyse the decolorization of a phenolic dye (phenol red) was also investigated using natural and synthetic mediators. The higher decolorization activity was observed with 1–hydroxybenzotriazole (HBT) as mediator at pH 4.5 and temperature 30° C

Analytic Technique For Active Mode-Locked Fiber Lasers

In this work, Aِmplitude modulation mode-locked fiber laser isstudied,by using Ytterbium Doped Fiber Laser, single mode fiber,operating with 1055 nm wavelength with 976 nm optical pump and AMMode-Locked by optical modulators. A grating pair is used to compensatethe normal dispersion. The effect of both normal and anomalous dispersionregimes on output pulses are investigated. Master equation of the Modelockingfiber laser is introduced .Pulse shapes for both dispersion regimesare assumed after modifying (Ginzburg-Landu equation) GLE which isessentially Generalized Nonlinear Schrödinger equation GNLSE and byapplying the moment method ,a set of five rate equations for pulse energy,pulse width ,frequency shift ,temporally shift and chirp ,which solutionsdescribed the pulse from round trip to the next and how they approach tosteady state values. To solve these equations numerically fourth order,Runge-Kutta method is performed through Mat-Lab 7.0 computer program.Result shows that, the output pulse width from the AM mode-Lockedequals to τ=0.8ps in anomalous and τ=1ps in normal regimes. The studyshows the stability of working in anomalous dispersion regime is betterthan normal regime

Synthesis and stabilization of gold nanoparticles by inverse reduction method using sodium citrate and sodium boro hydride as reducing agent

In recent decades, observed focus largely on the preparation of nano metallic elements, including the gold because of its unique properties and many applications. In most of these researches, the Turkevich' method has been adopted. This method is based on the reduction of gold ion Au3+ to the nano gold Au0 by the addition of a reducing agent to the gold salt H[AuCl4].3H2O. In this research, a novel simple and cost-effective technique is enhanced via the addition of the gold ion (Au3+) to the decreasing agent in opposite to the previous method. This is the cause to call it "The inverse method". In this inverse method one can control the amount of gold salt solution that add and stop this addition by observing the formation of the red color, which indicates the formation of gold nanoparticles(GNPs).Many reactions were conducted to prepare stable gold nanoparticles by usingchemical reducing agents such as (sodium tri-citrate, sodium borohydride),The reactions to prepare GNPs using these reducing agents were done at temperature of 60 – 80 °C.The resulted GNPs were characterized by UV- Vis spectra, zeta potential, atomic force microscope(AFM), scanning electron microscope(SEM), and transmission electron microscope(TEM).The absorption spectrum of the red GNPs solution appeared at the range of 520-540 nm. The gold nanoparticles which formed from various reactions have different shapes but the most prominent form is the spherical, and the sizes have also been different and appeared at the range of 14.5- 44 nm, which are consistent with published researches

The Influence of Substrate Temperature on the Structural , Morphology and Optical Properties of ZnS Thin Films Prepared by Pulsed Laser Deposition

Effects of substrate temperature on the microstructure, morphology, and optical properties of ZnS thin films were investigated. ZnS films were deposited on glass substrates by pulsed laser deposition at different substrate temperatures using a pulsed 532 nm Nd:YAG laser is presented . The structure and morphology of the film were studied by X-ray diffraction and atomic force microscopy, the average surface grain size and RMS surface roughness of the films increases with increasing substrate temperature. Optical properties of the films were determined from the transmittance data using Swanepoel model,Transmittances of film were measured by spectrophotometer. Additionally, the increase of the substrate temperatures increase the pores and the transmittance in the films, it was observed that the energy band gap is increased from 3.4 eV to 3.6 eV of the films are decreased with the increase of substrate temperature . Moreover , considerable improvement in blue response of the films was noticed with increasing substrate temperature