Engineering and Technology Journal

Nanocrystalline titania powder was prepared at room temperature via sol-gel method; using TiCl4 as precursor and absolute ethanol solution. After mixing, the gel solution was formed. Then the sol-gel dried and calcined at different temperatures. The size of the prepared nanoparticles was reduced by Nd-YAG Pulse Laser Ablation (PLA). The characterization of the TiO2 Nanoparticles in two phases was carried out by X-ray Diffraction (XRD) to investigate the phase structure. The Transmission Electron Microscope (TEM) result shows the particle size of nanoparticles after laser ablation less than 10 nm. Scanning Electron Microscopy (SEM) to obtain the surface morphological studies Results showed that anatase was the only phase in titanium oxide powders up to 500 °C, when the calcination increased in the region of 900 °C the phase transformation from anatase to rutile occurred in the TiO2 nanopowders. This paper shows a comparison between two phases of TiO2 Nanoparticles (anatase and rutile). Fourier Transform Infra-Red (FTIR) to study the vibrational frequencies between the bonds of atoms for synthesized TiO2 Nanoparticles. The Crystalline size of TiO2 Nanoparticles obtained was between (15 -70) nm for anatase at 500 °C and rutile at 900 °C. In FTIR analysis, all the peaks observed were around (400-700) cm-1 due to stretching and bending vibrations.

Intense Pulsed Light systems employ flash lamps as optical sources to provide the required light intensity with certain temporal profile for use in a large number of medical applications; namely, the aesthetic ones. Driving a flash lamp requires high voltage DC power supply, capacitive energy storage, and flash lamp triggering unit. Single and double-mesh discharge and triggering circuits were designed and built to provide intense light pulses of variable time durations. Variable energy and duration intense light pulses needed in aesthetic medical applications were obtained. The system was treated as circuit with a light pulse profile follows the temporal behavior of the exciting current pulse. Distributing the energy delivered to one lamp on to a number of LC meshes permitted longer current pulses, and consequently, increased the light pulse length and shortened its current rise time

The problem of the time evolution of localized quantum states for electrons in the semiconducting and metallic single wall carbon nanotubes (SWCNT) are studied analytically and numerically. In the long-wave approximation 10≤ka, where a is the interatomic distance of carbon atoms in the graphene lattice, 0k the carrier wave vector of the wave packet, we consider the time evolution of localized quantum states by using a model Hamiltonian. The localized quantum states are interpreted as a superposition of the valence band and the conduction band. The dynamic of the wave packet which is represented by localized quantum states in carbon nanotubes was considered with cylindrical symmetry. The time dependent average values of the angular and axial coordinate operators and its oscillations behavior are calculated. In addition, we taken into account the effect of an external magnetic field which is applied along the axis of carbon nanotube. The evaluations of the frequency and amplitude of zitterbewegung in the carbon nanotube are presented, which can be used for the experimental prospective studies in the nanoelectronic applications.
Heisenberg representation in the present study are used to evaluate the average values of the coordinate operators , furthermore , Schrödinger representation are used for interpreting

In this work preparation and characterization of a zinc metal target in isopropanol liquid at room temperature is carried out by PLAL technique at different laser fluency. The effect of laser fluencies during laser ablation process on the structure properties of the NPs is investigated.
We have use UV-visible spectroscopy, Atomic force microscopy and Energy dispersive X-ray (EDX) was used to evaluate the bulk atomic composition of NPs. The absorption peak of samples prepared in isopropanol solution is seen to be substantially blue shifted relative to that of the bulk zinc oxide due to the strong confinement effect. The technique offers an alternative for preparing the nanoparticles of active metal. The morphological investigation, carried out using (AFM), showed that the root mean square roughness is increased and the grain size of the obtained NPs are found to increase with the laser fluency. The use of isopropanol as solvent yielded spherical nanoparticles of 30–60 nm.

Electronic transport characteristics through a single molecule junction are investigated by using the Keldysh non equilibrium Green function (NEGF) model. The model consists of a molecular bridge (represented by a molecular orbital) attached with two free electron reservoirs (represents two metallic leads) and it is coupled with a vibrational degree of freedom (represents a molecular vibrational mode). The behavior of the electronic transfer through the molecular junction becomes more clearly visible by studying of the conductance-voltage characteristics. The numerical calculations are done based on this model to study the changes in conductance behavior through a single molecule junction in the resonant tunneling regime. According to our results, the conductance-voltage characteristics are influenced by (I) the electron-vibration interaction, (II) the molecular bridge-leads coupling strength, (III) the junction temperature, and (IV) the molecular vibrational mode energy. We conclude that the previous parameters have a significant role in determination of the electron conduction through the single-molecule junctions. Especially, the conductance is very sensitive to the molecular bridge-leads coupling strength and the junction temperature. These features provide important information about the study of the electronic transport phenomena in molecular junctions

Advanced materials are artificial structure materials that exhibit properties not found in nature. Material that has a negative refractive index (left-handed materials) is found to get a lot of interest in the literatures. Controlling the geometry of classical material may lead to have a negative refractive index in a certain frequency range. In this paper, we utilized from fractal geometry in our design. A Sierpinski Carpet fractal model is proposed. Calculations show that this model has a negative refractive index in the frequency range 7.5 GHz – 16.5 GHz. Wide band behavior of this model refers to its fractal shape

In this work, it was examined mechanisms that control internal cooling device (nano-homo junction diode) depending on thermoelectric Peltier effect, resulting in structures that are optimized thermal management. Peltier coefficient for short-length diode is theoretically investigated. It is found that the cooling power is governed by the carrier concentration, current density and the ratio of n-type region width to p-type region width. It has been determined the optimum value of the cooling power at the junction of ZnO in the optimum density at doping symmetrically on a certain value. The cooling power, temperature difference (temperature between the contact and the junction) and dimensionless figure of merit are found in this material for different thicknesses, then comparing between them. It has been simulated the homo junction diode using a MATLAB software with numerically calculated the Peltier coefficient for each layer in these diodes. It has been found that nano-homojunction introduce a significant improvement in the internal cooling performance.

This paper reports our recent studies on the generation of Cu NPs by ablation of metal targets using Q-switch Nd-YAG laser with Second Harmonic Generation(S.H.G) (λ=532nm) immersed in different aqueous media( Double Disteled Deionised Water (DDDW) and 1-Propanol) .Higher productivity and Smallest size have been produced by using 1-propanol solution compared to DDDW, which indicated that the productivity and NPs size were affected by the solution type. Optical properties measurements showed indirect optical energy gap of the produced Cu nanoparticle (3.717 and 4.887) eV , when the solution type change from DDDW to 1-Propanol respectively. The Surface topography studied by Atomic Force Microscopy, and shape were measured by using Scanning Electron Microscope SEM shows spherical shape while the composing of the prepared nanoparticle were determined by X-ray diffraction ,UV-Visible spectroscopy has been employed for the optical properties measurements.

In this paper , Zinc Oxide (ZnO) films were grown on glass substrates by Pulsed Laser Deposition (PLD) technique at room temperature under the vacuum pressure of 3×10−3 mbar. Employing a Nd:YAG pulses laser at wavelength 1064nm was used in this technique .The effect of number of laser pulses (200,500 and 800) at annealing temperature 450 C o on the structural, optical and electrical properties was studied. The
structure of the ZnO thin films was examined by X-Ray diffraction (XRD), it was
found that ZnO thin films are polycrystalline with many peaks, and the results of Atomic
Force Microscopy (AFM) indicated that all films have grain size around 90 nm. The
optical properties concerning the photoluminescence (PL) spectra were studied for the
prepared thin film. From the PL, the optical gap of the ZnO thin film was determined.
The Hall effect measurements confirmed that the ZnO thin films are n-type , While the
number of laser pulses is increasing, the charge carriers concentration (n) increases, and
Hall mobility (μRHR) decreases.

Doped and undoped nano particular silicate dioxide was prepared via sol–gel method under varying conditions. The optical properties of prepared samples were investigated by a variety of techniques, including X-ray diffraction, UV- Visible spectroscopy, FTIR spectroscopy and fluorescence spectroscopy. The peak of the fluorescence spectrum was recorded at the wavelength around to 1048nm, which it is close to known fluorescence peaks of Nd:YAG crystal in NIR region. A Judd-Ofelt analysis is performed to calculate the spectroscopic properties of Nd3+ ions embedded in SiO2 and compare it with spectroscopic properties of Nd:YAG crystal. The conclusions behind this study show that the doped silicate samples have a high peak emission cross-section σp , which gives an acceptable indication in the direction of using Sol-Gel technique to prepare Nd:SiO2 as a solid state laser active medium

Abstract
Transparent and conducting SnO2 thin film has been produced on (quartz and porous silicon) substrates using rapid photothermal oxidation of pure Sn in air at 600 oC oxidation temperature and different oxidation time. The structural properties and scan electron microscope of the prepared films were studied. The photovoltage properties of a Au/n-SnO2/p-PSi/c-Si solar cell are investigated under irradiation of Nd:YAG laser pulses. The porous Si layer is synthesized on a single crystalline p-type Si using electrochemical etching in aqueous hydrofluoric acid at a current density of 25 mA/cm2 for a 30-min etching time. The structure of the porous layer is investigated using scan electron microscope. The photovoltage properties are found to be dependent on the laser fluencies

Carbon nanostructures (CNTs) have been prepared by a Hydrothermal deposition technique based on the polymer Polyethylene glycol (PEG) dissolved in water and Ethanol alcohol of a new carbon sources materials mixed with (PdCl2) as a catalyst mixed with Sodium hydroxide (8gm NaOH) using Parr reactor at temperature (190°C) and forming the hybrid composite material (TiO2/Pd/MWCNTs) by the same way. Thence, deposited heterojunction material (TiO2/Pd/MWCNTs:n-Si) using the Pulsed Laser Deposition Technique (PLD), on the substrate of n-silicon wafer. The obtained (MWCNTs & TiO2/Pd/MWCNTs) are investigated by scanning electron microscope (SEM), X-ray diffraction (XRD) and X-ray Photo-electron Spectroscopy (XPS). Normal MWCNTs are formed multi-walled carbon nanotubes (MWCNTs) and carbon nanosheets (CNSs) but in little bit amount. MWCNTs were obtained as main products with lengths of (1.6–3 μm) and diameters of (30-60 nm) could be synthesized at as low temperature as (190°C). Deconvolution of the (C1s ) peaks which characteristic of C-C bonds, showed a main peak at (284.96 and 285.04 eV) with total amount (74.96 and 30.64 at%) for the product of MWCNTs and TiO2/Pd/MWCNTs composite respectively. Current – voltage characteristics of heterojunction showed that forward bias current change exponentially approximately with applied voltage at dark and this agreement with tunneling–recombination model. Also (I-V) characteristics under illumination of TiO2/Pd/MWCNTs heterojunction deposited on p-Si substrate (η=10.5) efficiency in Solar Cell

The electrospinning technique was used to fabricate 1D nanofibers of Zinc Oxide (ZnO). Polyvinylpyrrolidone (PVP) ̸ zinc acetate Nano fibers electrospun using solution containing PVP dissolved in ethanol and zinc acetate in distilled water were mixed, followed by calcination at 500°C for 3hours to remove the polymer. XRD pattern show the hexagonal wurtzite structure of ZnO NFs without any impurities. FESEM pictures show a network of nanofibers with diameters less than 100 nm and several micrometers in length of ZnO, these nanostructures increase the ratio of surface area to volume and improve the physical properties of the materials. The Photoluminescence (PL) of the films was studied and the energy gap and the optical properties were estimated. A photoconductor device was constructed by electroding the films with silver conducting electrode (IDE) using screen print method, The result shown that the resistance of the nanofiber films decrease dramatically when exposes to UV light. In addition, the change of conductivity with the change of wavelengths was studied also the photoconductivity was examined under different bias voltage

In this paper, Nano crystalline TiO2 and CuO additive TiO2 thin films were successfully deposited on suitably cleaned glass substrate at constant room temperature, and different concentration of CuO (0,5,10,15,20)% wt using pulse laser deposition(PLD) technique at a constant deposition parameter such as : (pulse Nd:YAG laser with λ=1064 nm, constant energy 800 mJ ,with repetition rate 6 Hz and No. of pulse (500).The films were annealed at different annealing temperatures 423K and 523 K. Effect of annealing on the morphological and electrical were studied. Surface morphology of the thin films has been studied by using atomic force microscopes (AFM). AFM measurements confirmed that the films have good crystalline and homogeneous surface. The Root Mean Square (RMS) values of thin films surface roughness are increased with the increase of annealing temperature. Also, The grain size increases with the increasing of concentration of CuO and annealing. The temperature dependence of the electrical conductivity and the activation energy at temperature ranging from (293-473)K of the as-deposited and films annealed at different annealing temperatures have been studied. The results show that as the film concentration of CuO and conductivity increases, while the activation energy(Ea1,Ea2) decreases. Both, the annealing and composition effects on Hall constant, RH, charge carrier concentration (NH), Hall mobility. Hall Effect

Transparent conducting oxides thin films of copper aluminium oxide (CuA1O2) were prepared from mixture of CuCl2 and Al2Cl3 salts by spray pyrolysis technique on a glass substrate at temperature (500oC). The as-deposited film show pure delaffosite phase of CuAlO2 by XRD spectra, also many peaks of CuAlO2 were appeared after annealing at different energy fluence. The optical transmission of thin films was measured by UV-VIS spectrometer and reach to 74% in visible region. The direct and indirect optical band gaps of the films are found in the range of (3.4-3.1) eV, and (2.1-1.5) eV, respectively depending on the annealing energy fluence at (300, 600, 900, 1200) mJ/cm2.

TiO2 thin films have been deposited at room temperature with different concentration of CdO of x= (0.0, 0.05, 0.1, 0.15 and 0.2) wt. % onto glass substrates by
pulsed laser deposition (PLD) technique using Nd-YAG laser with λ=1064nm,
energy=800mJ and number of shots=500. The structural, morphological and optical
characterizations of as- deposited films were carried out using X-ray diffraction
(XRD), atomic force microscopy (AFM), and UV–vis transmittance spectroscopy. The
Effect of CdO content on these properties was investigated. Characterizations by X-ray
diffraction show a polycrystalline film, with tetragonal structure and formation of
Rutile phase and many peaks (110), (101), (111) and (211) were appear. In addition,
AFM investigation shows no cracks in the formed layer. The optical properties
concerning the absorption and transmission spectra were studied for the prepared thin
films using an ultraviolet–visible near-infrared spectrophotometer. The results show
that the transmittance of the TiOR2R film in the visible domain reaches 75%.Optical band
gaps were calculated and found to be (3.62, 3.54, 3.45, 3.3 and 3.21) eV for the
concentration of CdO x= (0.0, 0.05, 0.1, 0.15 and 0.2) wt. % respectively. At 350 nm
the refractive index, extinction coefficient and dielectric constant were determined

Designing Laser Detection and Tracking System (LDTS) needs meeting some certain requirements, one of these requirements is meeting tracking criteria for quadrant photodetector (QPD) at near and far detection range for the target in question through simulating these requirements. A reflecting truncated tetrahedral prism technique design and four separate photodetectors of certain shapes are introduced as a method to avoid tracking failure case.

Abstract
In this research the effect of laser irradiation N2 at 337 nm on the optical properties of the nanocrystalline In2O3 films subjected to laser irradiations with different power average (0.85, 1.70, 2.125 and 2.55mW ) for irradiation time (5min). By, by using UV-VIS spectrophotometer technique, can many of the optical properties account of study change spectral transmittance and absorbance of these membranes, such as the expense of absorption coefficient, and energy gap for direct transitions It was found that the band gap decreases when the thickness increases and the band gap values ranges between 3.5eV to 3.0eV. and calculate the reflectivity and extinction coefficient and refractive index and dielectric constant real and imaginary and optical connectivity. the exposure of the as deposited films to a selected dose of laser irradiation, the optical properties films varies with increase in the power average

NiO thin films have compounded by pulsed laser deposition on glass and silicon (111) substrates, employing Q-switching Nd:YAG laser. Structure, grain size and optical properties have analyzed by using FTIR, AFM and UV-VIS spectroscopy. FTIR spectra conformed of NiO bonding. AFM images show the particle size about ~66nm. The optical transmission results premiered the transparency of the NiO films is greater than 70% in the visible region with optical band gap 3.85eV. The current voltage characterization of NiO/Si heterojunction has good rectifying

Tin Oxide nanoparticles (SnO2-NPs) were prepared by mixing (SnCl4.5H2O) with distilled water at room temperature. The samples were characterized for their crystalline structure, morphology and chemical structure by using X-ray diffraction (XRD), Rietveld refinement, scanning electron microscopy (SEM) and fourier transform infrared spectroscopy (FTIR). The XRD data and Dicvol 91 software analysis the crystal system was found to be tetragonal structure for samples prepared under stirring time for (24,48,72) h with (a=4.745 , c=3.184), (a=4.768 , c=3.255) and (a=4.776 and c=3.257) respectively. The average of crystallite size calculated by using SEM it was 9.45 nm, 14.7 nm and 21.5 nm, for the same times, previously mentioned of stirring. The effect of stirring time on the crystal lattice distortion ratio, specific surface area and dislocation density was discussed. The optical band gap values of SnO2-NPs were calculated to be about 3.4eV, 3.37eV and 3.2eV under stirring time for 24 h, 48 h and 72 h respectively by optical absorption measurement

Iron, copper and stone samples were cleaned by Nd: YAG laser using different number of nano laser pulses at variable intensities. Fundamental (1.06 μm) and frequency doubled (0.53 μm) wavelengths cleaning efficiency was tested by measuring the crust and oxide removal rate. A laboratory environmental chamber was built and utilized to study the effect of processing gas on the cleaning process. Surface ref lectivity, SEM and optical microscope investigations indicated the effectiveness of Nd: YAG laser cleaning without damaging the surface. The use of high laser pulse energies helped achieving reasonably good and fast cleaning, whereas low laser energy required larger number of pulses, but ensured safe cleaning. Optimum results were obtained when using the fundamental laser wavelength under O2 environment