Silver-Poly vinyl alcohol Ag/ PVA nanocomposite films were prepared by casting method at room temperature with different amount of AgNO 3 solution (0.001, 0.0015, and 0.002ml). The prepared nanocomposites were characterized using UV-VIS spectrophotometer and the optical properties were investigated in the wavelength range 300-800 nm. The absorption peaks showed a shift towards higher wavelength with increasing AgNO 3 concentration while the energy band gap and absorption edges shifted towards lower energies with the increase of AgNO 3 concentration.
Transportation of toxic elements from air, water and soil is the main reason for agriculture crops pollution. Therefore, fast detection of heavy metals is very important for ensuring the quality and safety of crops. Laser-induced breakdown spectroscopy (LIBS), coupled with univariate and multivariate analysis, was applied for quantitative analysis of Cr, Pb, Cu and Cd in twelve kinds of rice available in local markets. Qualitative and quantitative analysis of the samples were achieved by using the locally developed LIBS set up equipped with Q-switched Nd: YAG laser and optical spectrum analyzer. Atomic absorption spectrometry (AAS) was used not only to validate the analysis results but also to establish the essential calibration curves. Distribution pattern of detected metals and possible contamination sources were analyzed by radar plot and multivariate statistics including PCA. In this study, harmful metals have been analyzed in all samples. The average content for harmful metals were 0.040 mg/kg for chromium (VI), 0.051 mg/kg for lead, and 0.041 mg/kg for copper and 0.043 mg/kg for cadmium.
In this work, laser-induced breakdown spectroscopy (LIBS) analysis is optimized for direct estimation of elemental composition, thermal conductivity and hardness for Ni-Cr-Nb alloys. These alloys were chosen with a variable elemental content of niobium and chromium. The influence of laser energy and shot numbers on measuring line intensity was investigated. Based on the ratio between two spectral lines, calibration curves were formed to estimate the element concentration and LIBS results were confirmed with related energy-dispersive X-ray spectroscopy (EDS) data. Hardness and thermal conductivity estimation using LIBS were done by measuring the ratio between two spectral lines, plasma excitation temperature and electron density for different samples. Semi-empirical formulas correlated hardness and thermal conductivity with plasma temperature were established.
We investigate the spectral response of nanostructured copper oxides thin film. Gold was doped in two different concentrations (2% and 4%) using the spray method. A novel ammonia gas sensor at various concentrations (0–500 ppm) was fabricated by replacing CuO films with a clad region. In addition, the effect of gold doping on structural, optical, and morphological properties has been demonstrated. The study shows that the spectral intensity increases linearly with ammonia concentration. The 4% Au doped CuO presents higher sensitivity compared with 2% doped and pure copper oxides. Time response characteristics of the sensor are also reported.
In this study, Calibration-free Laser-induced breakdown spectroscopy (CF-LIBS) was applied to quantitatively analyze the elemental composition of Ti-6Al-4V titanium based alloy samples with no need for matrix-matched calibration procedure. Nd:YAG pulsed laser operating at a wavelength of 1064 nm was focused onto the sample to generate plasma. The spectrum of plasma was recorded using spectrophotometer then compared to NIST spectral lines to determine characteristic wavelengths, energy levels and other spectroscopic parameters. The values of plasma temperature obtained using Boltzmann plot for four examined samples ranged from 7439 to 6826 K while the electron density for each element was determined using Boltzmann-Saha equation. The concentration of Ti, Al, V and Fe has been determined and were within the samples nominal concentrations obtained from XRF analysis. The calculated average relative errors of Ti, Al, V and Fe were 0.39%, 4.38%, 4.94 % and 8.2 %, respectively. Finally, there was a direct proportionality relation between the ratio of ionic to neutral emission lines of Ti for four samples and the surface hardness values measured mechanically using Vickers hardness test. The ratio at had the best linear regression value (R2=0.95) which indicates the best correlation with surface hardness.
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