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In this work, optical properties including absorption coefficient (α), linear refractive index (n) as well as the energy gap (Eg) of crystal violet dye was estimated in two phases. The first phase: when the dye was dissolved in water at different concentrations (1 × 10-1, 1 × 10-2, 1 × 10-3, 1 × 10-4, 1 × 10-5ml). The second phase is the deposition of polyvinyl alcohol for different thicknesses (2, 4, 6, 8 and 10 µm) and with fixed concentration (1 × 10-3 ml) as thin films. It was found that the linear optical properties increased with increasing thicknesses while the energy gap is increasing from 3.9 to around 4.1 eV with increasing CV concentrations resulting from the indirect transitions. [ABSTRACT FROM AUTHOR]

Aluminum Oxide (Al2O3) nanocrystalline have been deposited at varying deposition time of 1h, 2h and 3h on glass substrate via chemical deposition (CD) technique. Morphological, structural and optical properties were obtained to study the influence of the deposition time on the Al2O3 films. The surface morphology and crystallinity show that the particle size decreased from 56.32 nm to 35.89 nm when the deposition time increased from 1h to 3h. Also, the average diameter decreased from 80.78 nm to 71.88 nm with increasing time from 1h to 3h respectively. The optical properties were carried out using UV-Vis spectroscopy measurements and the result indicated that the transmittance spectral decreased when the deposition time increasing. In addition, the energy gap (Eg) decreased from 3.88 to 3.69 eV when the deposition time increasing from 1h and 3h respectively. The results indicated that the optical characterizations depend stronger on the deposition time. [ABSTRACT FROM AUTHOR]