الفهرس 
THEORETICAL BACKGROUND AND UTERATURE REVIEWOnly 14 pages are availabe for public view
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Abstract
Synthesis of CdSe and ZnSe nanoparticles were performed using the modified chemical recipe. The structural nature and optical properties of the as-synthesized nanoparticles were characterized by using: X-ray diffraction (XRD), energy dispersive X-rays analysis (EDX), transmission electron microscopy (TEM), and Fourier transform infrared (FT-IR). The crystal structure of the CdSe quantum dots was solved and refined from X-ray powder diffraction data by full-profile Rietveld method. The structure is
wurtzite hexagonal, space group P63mc, a = 4.2569(3), c = 7.0022(5) A,
with Cd at (1/3, 2/3,0) and Se at (1/3, 2/3, 0.37904(36)). High-resolution TEM (HRTEM) was employed to characterize the particle size, shape and morphology of the CdSe nanocrystals. HRTEM showed monodispersed spherical nanocrystalline CdSe with diameters of less than 8 om, and lattice fringe measurements corresponded to d-space values of planes within the hexagonal wurtzite CdSe that consistent with the value in the standard card ((JCPDS: 77-2307]. The UV-Vis absorption and PL spectra showed the well-dispersed CdSe nanocrystals in toluene were recorded at room temperature (RT). It can be seen that the line width of the luminescence spectrum was symmetric and narrow, which obviously revealed that the as prepared CdSe QDs were nearly monodisperse and homogenous with peak position at 566.36 nrn, (2.19 eV) and full width at half maximum (FWHM),
33.26 ±1om.
A saturated solution of QD- C<46Ses4 and QD- Zn49Ses1 has been prepared in a toluene solvent. The thin film coated on a pre-cleaned glass substrates using a spin coater unit rotated by 1000 RPM, with rate of dropping 14 drop/10 sec, then waited for 15 s and re-dropping in the same