激光诱导击穿样品产生的等离子体寿命通常在微秒量级,对其时间演化过程进行了解有利于优化信号采集。定标曲线是定量分析的基础,并且与测量灵敏度和准确度密切相关。采用聚焦的脉冲激光束击穿样品形成等离子体,其发射光谱由中阶梯光栅光谱仪分光,并由增强型电荷耦合器件(ICCD)进行光电探测采集。为了实现对金属元素的激光诱导击穿光谱(LIBS)测量,在石墨中分别加入Ca,Al,Na,K等元素制作成片状实验样品,利用实验装置进行了系统的激光击穿光谱探测研究。应用ICCD100 ns光学门宽的时间分辨率,通过实验得到了等离子体的时间演化特性曲线,分析了激光击穿固体样品后各待测元素的演化过程。根据含有不同浓度的同种元素样品的LIBS实验结果,归纳出各元素浓度与谱线强度的定标曲线,且大多数定标曲线的线性拟合相关度较高。同一元素不同波长的谱线,其定标曲线的斜率不同,对其差异进行了分析。

The life of laser-induced plasma is usually in the μs region,and it is necessary to study the temporal evolution of the plasma in order to optimize the signal detection. Calibration curve is the basis of quantitative analysis,which closely relates to the sensitivity and accuracy. The plasmas were induced by a focused,pulsed laser. The emission spectra of plasmas were then dispersed by an Echelle spectrograph and detected by an intensified charge-coupled device (ICCD). Graphite was the major constituent of the sample,and Ca,Al,Na,K elements were added to pellet the sample respectively. The spectra including the emission lines of Ca,Al,Na,K elements were presented. The temporal evolution curves of the plasmas were obtained via the experimental system of using the gating periods of 100 ns of ICCD. The calibration curves of the lines intensities were obtained. The calibration curves were also analyzed,whose slope are different for the spectra line of the same element of the sample at different wavelength.