thin films of se:2.5% as were deposited on a glass substates by thermal coevaporation techniqi=ue under high vacuum at different thikness

A nanocrystalline CdS thin film with 100 nm thickness has been prepared by thermal evaporation technique on glass substrate with substrate temperature of about 423 K. The films annealed under vacuum at different annealing temperature 473, 523 and 573 K. The X-ray diffraction studies show that CdS thin films have a hexagonal polycrystalline structure with preferred orientation at (002) direction. Our investigation showed the grain size of thin films increased from 9.1 to 18.9 nm with increasing the annealing temperature. The optical measurements showed that CdS thin films have direct energy band gap, which decreases with increasing the annealing temperature within the range 3.2- 2.85 eV. The absorbance edge is blue shifted. The absorption

Effect of [Cu/In] ratio on the optical properties of CuInS2 thin films prepared by chemical spray pyrolysis on glass slides at 300oC was studied. The optical characteristics of the prepared thin films have been investigated using UV-VIS spectrophotometer in the wavelength range (300-1100 nm). The films have a direct allow electronic transition with optical energy gap (Eg) decreased from 1.51 eV to 1.30 eV with increasing of [Cu/In] ratio and as well as we notice that films have different behavior when annealed the films in the temperature 100oC (1h,2h), 200oC (1h,2h) for [Cu/In]=1.4 . Also the extinction coefficient (k), refractive index (n) and the real and imaginary dielectric constants (ε1, ε2) have been investigated

Indexing manuscripts is one of the important technical operations carried out by the indexer because of the descriptive or bibliographic data it provides

مشكلة البحث والحاجة إليه.

     من المشاكل الشائعة والمألوفة بين طلبتنا هي قلق الامتحان، ذلك القلق الذي يبقى طبيعيا مادام في مستواه الطبيعي وهو يختلف من طالب الى آخر في صور ظهوره المختلفة فقد يبدو واضح الأعراض لدى بعض الطلبة؛ فقد يؤثر على تذكرهم للمادة العلمية أو الإجابة على بعض الأسئلة أو يؤثر على تركيزهم وتشتت انتباههم وتفكيرهم والتوتر وسرعة الانفعال. (11: بلا)

وكل

عاش البيروني في القرن الرابع الهجري الذي كان يمثل مثاراً للصراعات السياسية والفكرية، ومن خلال هذه الأوضاع المتأزمة برز البيروني كعلم من اعلام هذا القرن، ومن أبرز مفكري الحضارة العربية الاسلامية فنجده كتب في الرياضيات

    Indexing manuscripts is one of the important technical operations carried out by the indexer because of the descriptive or bibliographic data it provides.

              In the present work, poly methyl methacrylate (PMMA) doped with Rhodamine 6G was prepared. The spectral properties (absorption and fluorescence) of the films were studied at different concentrations (1x10^-5, 2x10^-5, 5x10^-5, 7x10^-5, and 1x10^-4mol/l). The investigated samples were made in the form of thin films. This was achieved by dissolving a certain weight of PMMA in a fixed volume of chloroform, composite films was with thickness (25.8μm) at room temperature. The achieved results were pointed out that absorption and fluorescence spectra have taken a wide spectral rang so when increased the concentratio

Sb2S3 thin films have been prepared by chemical bath deposition on a glas sub Absorbance and transmittance spectra were recorded in the wavelength range (30-900) nm. The effects of thickness on absorption coefficient, reflectance, refractive index, extinction coefficient, real and imaginary parts of dielectric constant were estimated. It was found that the reflectivity, absorption coefficient , extinction coefficient, real part of dielectric constant and refractive index, all these parameters decrease as the thickness increased, while the imaginary part of the dielectric constant increase as the thickness incre