An Investigation of Enhanced Laser-Induced Spark Emission and Material Ablation Following Sequential Laser PulseExcitation

南卡罗来纳大学的Stanley Angel教授与意大利巴里大学的A.DeGiacomo博士合作，得到了分析和表面化学项目的支持。通过实验和理论，该团队正在研究一种原子分析方法-激光诱导击穿光谱(LIBS)的机理，以改进LIBS作为一种能够在不准备样品的情况下分析固体的技术。特别是，双脉冲序列已经导致LIBS增强了100倍，但增强的机制、更大的等离子体体积、更低的连续本底和更高的电子温度尚不清楚。将进行系统的研究，以检验这种影响是由于样品上方的等离子体重新加热和预电离造成的假设。例如，该团队将尝试通过使用辉光放电创建预电离区来复制双脉冲结果。将以三种样品基质(玻璃、钢和纯金属)中的四种元素Al、Fe、Cu和Cr作为模型系统进行研究，应用范围包括环境、健康、法医、地质和工业分析。这项工作将使学生能够与国际科学家以及劳伦斯·利弗莫尔国家实验室的工作人员互动。

Professor Stanley Angel of the University of South Carolina is supported by the Analytical and Surface Chemistry program in a collaboration with Dr. A. DeGiacomo of the University of Bari, Italy. Through experiments and theory, the team is studying the mechanism of an atomic analytical method, laser-induced breakdown spectroscopy (LIBS), in order to improve LIBS as a technique capable of analyzing solids without sample preparation. Particularly, a dual pulse sequence has resulted in 100-fold enhanced LIBS, but the mechanism for the enhancement, larger plasma volume, lower continuum background and increased electron temperature are not known. Systematic studies will be conducted to test the hypothesis that the effects are due to plasma re-heating and pre-ionization above the sample. For example, the team will attempt to duplicate dual-pulse results by creating a pre-ionized region using glow discharge. Four elements, Al, Fe, Cu and Cr, in three sample matrices (glass, steel and pure metals) will be studied as model systems.Applications include environmental, health, forensic, geological and industrial analysis. The work will enable students to interact with international scientists as well as staff at the Lawrence Livermore National Laboratory.