الفهرس 
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Abstract
Composites films of polyvinyl alcohol PVA and PVA doping with coumarin are prepared by solution casting method with different concentrations of coumarin (30 ppm, 70 ppm, 110 ppm, 150 ppm). The prepared films were exposed to 2nd harmonic of Nd:YAG laser at 532 nm of power 250 m Watt, at room temperature i.e, with intensity 3.75Kj/cm2, 7.50kj/cm2, 11.25kj/cm2. The composites films are characterized by UV-visible, FT-Raman spectroscopy before and after irradiation. Optical absorption showed gradual increase with coumarin concentration before irradiation. On the other hand the absorption was found to decrease with laser irradiation intensity. FT-Raman spectroscopy showed a remarkable increase in the intensity of main vibrational bands after irradiation. This effect might be related with photo-ablation of coumarin particulates leading to a reduction on particulates size which correspondingly is related with surface enhancement of Raman bands.
In addition, Composite films are investigated before irradiation by Fourier transform infrared (FT-IR), Atomic force microscopy, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). FT-IR analysis of samples showed that no drastic changes were seen in the spectra due to the addition of coumarin to PVA. The RMS roughness of the surface for prepared films decrease as the coumarin concentration is increased. DSC analysis showed that the (Tg) glass transition decrease in temperature with increase in coumarin concentration.