Search

In this work, the optical emission spectrum technique was used to analyze the optical emission spectrum of (CdO: Fe) plasma produced by laser Nd: YAG with a wavelength of (532) nm, a period of 10 ns, and a focal length of 10 cm in the energy range of (200-500) mJ. The electron temperature (Te) was determined using the method of line intensities ratio. Using the Saha-Boltzmann equation, the electron density (ne) was determined. Other plasma parameters such as plasma frequency (fp), Debye length (λD) and Debye number (ND) were also measured. The CdO: Fe (at a mixing ratio of X= 0.5.) plasma spectrum was observed for different energies. As a function of the laser energies, the changes in electron temperature and densities were studied. The value of the electron temperature, at X=0.5, was (0.420 - 1.160) eV for laser energy (200-500) mJ, respectively.

This study shows the effects of copper material electrode, applied voltage, and different pressure values on electrical discharge plasma. The purpose of the work is the application of the spectral analysis method to obtain accurate results of nitrogen plasma parameters. By using the optical emission spectroscopy (OES), many N2 molecular spectra peaks appeared in the range from 300 to 480 nm. Also, some additional peaks were recorded, corresponding to atomic and ionic lines for nitrogen, target material, and hydrogen, in all samples. The electron density (ne) was calculated from the measurement of Stark broadening effect, which was found to decrease with increasing pressure from 0.1 mbar to 0.8 mbar. The higher emission intensities occurred at 0.2 mbar working pressure and were reduced with higher pressure. The vibrational temperature (Tvib) for N2 increased from 0.17 to 0.33 eV with increasing the pressure from 0.15 mbar to 0.2 mbar, then decreased to 0.25 eV with increasing the pressure to 0.8 mbar. Other plasma parameters were studied, which are electron temperature (Te), plasma frequency of electron ( ), and Debye length (λD).

The present work aims to achieve pulsed laser deposition ofTiO2 nanostructures and investigate their nonlinear properties using z-scan technique.The second harmonic Q-switched Nd: YAG laser at repetition rate of 1Hz and wavelength of 532 nm with three different laser fluencies in the range of 0.77-1.1 J/cm2 was utilized to irradiate the TiO2 target. The products of laser-induced plasma were characterized by utilizing UV-Vis absorption spectroscopy, x-ray diffraction (XRD), atomic force Microscope (AFM),and Fourier transform infrared (FTIR). A reasonable agreement was found among the data obtained usingX-Ray diffraction, UV-Vis and Raman spectroscopy. The XRD results showed that the prepared TiO2 thin films were all crystallite structure with no impurity peaks of other elements. Also, their peak intensities were increased with increasing the ablating laser fluency. AFM measurements indicated that,during pulsed laser deposition, as the laser fluency was increased, the average diameter of the prepared TiO2 nanoparticles (TiO2 NPs)was decreased from 86 to 57 nm, althoughthe differences were increased with the increase in the laser fluency. The multiphoton absorption was investigated using ultra-fast femtosecond laser with the z-scan method.The impact of thickness of the prepared films on the non-linear absorption coefficient was studied as well.

The current study was achieved on the effects of laser energy and annealing temperature on x-ray structural and optical properties, such as the UV-Visible spectra of cadmium sulfide (CdS). The films were prepared using pules laser deposition technique (PLD) under vacuum at a pressure of 2.5×10-2 mbar with different laser energies (500-800 mJ) and annealing at a temperature of 473K. X-ray diffraction patterns and intensity curves for the CdS showed that the formation of CdS multi-crystallization films at all laser energies. The optical properties of the films were studied and the variables affecting them were investigated in relation to laser energy and changes in temperature.