Zinc oxide photocatalyst was synthesized through a low‐temperature co‐precipitation process using zinc sulfate as precursor for the degradation of Acid Red 57 (AR57) under UV irradiation. The activities of the prepared photocatalyst at different calcination temperatures (400, 500, and 600 °C) were investigated. The synthesized zinc oxides were characterized by different techniques such as X‐ray diffraction, scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, N2 adsorption–desorption, and pH titration for the determination of the zero‐point charge (pHZPC). The efficiency of photocatalytic degradation of ZnO prepared at the calcination temperatures of 400, 500, and 600 °C was 90.03, 77.67, and 72.71%, respectively, after 190 min. The kinetics and scavengers of the reactive species during the degradation were also investigated. It was found that the degradation of AR57 fitted first‐order kinetics and the OH• radicals were the main species. During irradiation, the formation of OH• free radicals was ascertained by photoluminescence studies using terephthalic acid as the probe molecule.
The interaction of 20 ns, 3 J laser pulses with solid boron nitride targets is studied spectroscopically in the wavelength range from 30 to 300 Å, and by taking pinhole pictures at short wavelengths. The experiments were carried out for different angles of incidence of the laser beam and as a function of the depth of the hole in the target. Typical temperatures are from 22 to 45 eV. It is observed that the heating of the plasma occurs at the bottom of the hole and that the hole is along the axis of the direction of the laser beam.
Spectroscopic investigations are made on expanding plasma plumes created by a 20 ns, 3 J laser pulse impinging perpendicularly onto targets of boron, boron carbide and boron nitride. The characterization of the plasma plumes is carried out spectroscopically in the wavelength range from 30 to 330 Å, and by taking pinhole pictures at shorter wavelengths. The experimental results are compared with the plasma plume produced from different targets under the same experimental conditions. The calculated plasma temperatures are 50 eV and 30 eV at 1 mm from the target in the cases of boron and boron carbide targets, respectively. Electron temperature measurements were made as a function of laser irradiance, distance from the target surface and time elapsed after the maximum of the laser pulse.
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