激光诱导击穿光谱技术以其无需样品预处理、 分析速度快、 能实现多元素同时检测和远程分析等优点已经被广泛应用于诸多领域的物质成分定性或定量分析。 该技术的理论基础是激光诱导等离子体。 对等离子体光谱参数(如光谱谱线强度、 等离子体温度等)的准确测量是利用该技术进行定性或定量分析的前提条件。 实际的实验系统中, 由于仪器本身固有的性能限制, 会造成采集光谱信号的失真, 从而限制等离子体光谱参数的精确测量或计算。 为了克服仪器固有性能的影响, 分析了实验系统所用中阶梯光栅光谱仪和传输光纤的固有性能缺点对光谱信号背景噪声和元素谱线绝对强度的影响, 然后采用剥峰法对光谱信号中存在的锯齿状背景噪声进行扣除, 利用辐射定标光源的标准光谱数据对谱线绝对强度进行校正, 并对比了背景扣除和强度校正对等离子体谱线强度和等离子体温度的影响, 实验表明谱线强度校正对合金钢等离子体380 nm以下的光谱信号具有较大影响, 通过背景扣除和强度校正后, 等离子体温度由13 401.75 K降低至8 980.72 K, 玻尔兹曼平面法求解等离子体温度的拟合决定系数由0.60提高至0.91。 因此在光谱数据处理之前对测量光谱进行背景扣除和强度校正是十分必要的, 为提供可靠地光谱数据进行物质成分定性或定量分析奠定了基础。

Laser-Induced Breakdown Spectroscopy (LIBS) has been widely used in more and more fields as a method for qualitative or quantitative analysisas a result of its unique advantages, such as no sample preparation, fast analysis speed, multi-element detection simultaneously, remote analysis, etc.. The theoretical basis of this technique is laser-induced plasma. Accurate measurement of spectral parameters of the plasma (such as spectral line intensity and plasma temperature) is a prerequisite for qualitative or quantitative analysis by LIBS. However, due to the inherent performance of the instrument in practical experiments, the distortion of the acquired spectral signal can be caused, which limits the precise measurement or calculation of the plasma spectral parameters. In order to overcome the impact of instrument performance, the influences of the inherent shortcomings of the Echelle spectrograph and the transmission fiber used in the experiment on the background noise and the absolute intensity of the spectral line were analyzed. Then, the spectral background noise was deducted by the peak clipping algorithms, and the absolute intensity of the spectral line was corrected by using the standard spectral data of the radiometric calibration sources. The spectral line intensity and plasma temperature were compared. It has been shown that the intensity correction has a great influence on the spectral signal with the wavelength less than 380nm forthe alloy steel sample. After the background subtraction and intensity correction, the plasma temperature was reduced from 13 401.75 to 8 980.72 K, and the fitting coefficient of Boltzmann plot for the plasma temperature was increased from 0.60 to 0.91. Therefore, it is necessary to take the spectral pretreatment before spectral data processing. It provides the basis to obtain the reliable spectral data for the qualitative or quantitative analysis of the material composition.