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为了改善激光诱导击穿光谱的质量,提高激光诱导击穿光谱(LIBS)技术对土壤样品中痕量元素的检测能力,研究了碳质空腔距离样品表面的高度变化对等离子体辐射强度的影响.结果表明,当有空腔约束等离子体时,其辐射强度比没有空腔约束时明显增强;随着空腔距离样品表面高度的加大,等离子体辐射强度逐渐升高,并在11 mm处达到最强,随后减弱.计算可知,样品中元素Fe,Mn,K和Ti在空腔距离靶面11 mm处的谱线强度和光谱信噪比与无空腔约束时相比,都有较大提高.最后,用Boltzmann图方法和光谱线Stark展宽法测量了等离子体的电子温度和电子密度,对等离子体辐射增强的机理进行了讨论.
In order to improve the quality of laser-induced breakdown spectroscopy and improve the ability of laser-induced breakdown spectroscopy (LIBS) to detect trace elements in soil samples, the influence of the height of the carbonaceous cavity on the surface of the plasma was studied. The results show that when the cavity confines the plasma, its radiation intensity is obviously enhanced than that without the cavity constraint. As the cavity height increases, the plasma radiation intensity gradually increases, and at 11 mm Calculated and then weakened.According to the calculation, it can be seen that the spectral line intensities and spectral signal-to-noise ratios of the elements Fe, Mn, K and Ti in the sample at a distance of 11 mm from the target surface are higher than those without a cavity constraint Finally, the plasma electron temperature and electron density were measured by Boltzmann plot method and spectral line Stark broadening method, and the mechanism of plasma enhanced radiation was discussed.