Investigation On Laser Induced Breakdown Spectroscopy Of Al Element In Tiauid Matrix

Elemental analysis based on the emission spectrum from the plasma generated by focusing a high power density laser beam on the sample surface is known as Laser-Induced Breakdown Spectroscopy (LIBS). L IBS technology as a new quantitative analysis method is fast, the samples less destructive. It can realize online, remote monitoring and also can be applied in the field that can not be reached by the traditional chemical analysis technique. LIBS technology applied in the high temperature, remote monitoring of toxic, shows its unique advantage. The application of LIBS in the development of superconducting thin films preparation, nano materials, environmental science, medicine, archaeology, metallurgy and other fields has a broad prospect. When the power density of laser on the sample surface is high enough, the sample is vaporized, and then the neutral and ionic species are formed at excited states. The spectral lines emitted from these species can be used to determine the sample composition and the trace concentration quantitatively. So this technique can be used to detect the trace element contained in gaseous, droplet, and liquid samples. LIBS is at its development period compared to the other developed analysis techniques, but its potential advantages make it be a wide concerned research field.In chapter1, the characteristic, development of LIBS were introduced. The basic theory of LIBS such as the property of the laser induced plasma, the microcosmic mechanism of LIBS, and the foundation of LIBS as a quantitative analysis method were presented. The experiment setup and the sample preparation were described in chapter3in detail.In the fourth chapter, the influence of ICCD gate width, ICCD gate delay, and the pulse laser energy on LIBS signal intensity were explored for the single laser pulse ablation. The optimum experiment parameters and LIBS limit of detection of Al396.15nm spectral line were obtained. Experimental results show that the optimization of experimental parameters for laser energy of50mJ, ICCD gate width150ns and signal acquisition delay1200ns. In the optimized conditions, spectral line intensity of Al I at394.40nm and396.10nm with different concentrations in experiments were measured, and the detection limit of Al element in water solution and mixed solution were26.79ppm,28.85ppm respectivly.In the fifth chapter, the influence of inter-pulse delay on the Al396.15nm line intensity, the relevant comparison of two regimes in the same conditions and the detection limit of Al element in solution were discussed with double pulses laser case. The experiment result showed that the optimum value of the experimental parameters of inter-pulse delay at1000ns, signal acquisition delay at1100ns. In the optimized conditions, spectral line intensity of Al I at394.40nm and396.15nm with different concentrations in experiments were detected, and the detection limit of Al element in water solution and mixed solution were11.93ppm and14.46ppm respectively. An improvement of the limit of detection of about3folds was achieved using DP-LIBS when compared to SP-LIBS case.In the last part of this thesis, a general discussion of our work and some suggestions on the future research are presented.