الفهرس 
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Abstract
New laser dyes 2-(6-Acryloyloxy-3-oxo-3H-xanthen-9-yl)-benzoic acid ethyl ester (AXOBE) and 2-(6-Allyl-3-oxo-3H-xanthen-9-yl)-benzoic acid ethyl ester (AXBE) were prepared and their chemical structures were confirmed by 1H NMR, 13C NMR, mass spectra and elemental analysis.The absorption spectra of the new laser dyes in THF were measured at different concentrations. Kinetic studies of their free-radical copolymerisation were evaluated with methyl methacrylate as standard monomer. Effects of different solvents on the rate of free-radical copolymerization with MMA were also studied. DMF was found to be the most suitable solvent for this copolymerization process. Effects of the initiator concentrations as well as the temperature on the rate of free radical copolymerisation of the new monomers with MMA were studied. It was found that, the activation energy of polymerisation of AXBE with MMA is higher than that in case of AXOBE. To study some of the optical properties, bulk free radical polymerization of the new laser dyes (AXOBE) & (AXBE) were carried out with methyl methacrylate (MMA) & 2-hydroxyethyl methacrylate (HEMA) Electronic spectra of the fluorescein, AXOBE and AXBE in solutions and polymer hosts were measured. Absorption and emission spectra of the new laser dyes in both solutions and polymer hosts have significant higher intensities than in fluorescein. Superradiance efficiencies for AXOBE and AXBE in polymeric hosts were obtained using third harmonic Nd-YG laser (at 355 nm) and they were found to be 0.85% and 0.92% respectively.The threshold pump energy for AXOBE and AXBE are found to be 5.24 mJ and 5.03 mJ respectively. Lifetime of excited state of new laser dyes was measured by using the setup shown in figure (3.3). The fluorescence lifetime values of the new laser dyes were calculated and found to be 5-6nS which agrees with the range of the other standard laser dyes(4-15nS) depending upon the host type of the laser dye (liquid, glass, sol-gel, polymer,…etc). Some photophysical parameters such as radiative-decay rate constant (kr), nonradiative-decay rate constant (knr), radiative lifetime (τ0) and fluorescence quantum yield (Φf) are calculated to explore the efficiency of the new laser dyes in polymer host as solid-state laser source. Photostability of the new laser dyes AXOBE and AXBE were also measured by two different methods. The first one depends upon exposing the polymeric laser dye to uv-radiation and studying the change in their absorption and emission spectra corresponding to photodegradation of dyes. The second method depends on studying the output energy of laser dyes as a function of number of pulses of third harmonic Nd-YG laser (5.4 mJ) with pulse repetition rate of 5Hz. It was found that, after 150 and 170 pulses, the output energy of the polymeric dyes AXOBE and AXBE respectively decrease to their half initial output energy.