Abstract Laser ablation - spark discharge - optical emission spectroscopy (LA-SD-OES) and Laser-induced breakdown spectroscopy (LIBS) are applied for the analysis of minor elements Manganese (Mn) and Chromium (Cr) in steel and for the chemical imaging of micro-patterned photoresist layers. In LA-SD-OES a weak laser pulse (typical energy 50 μJ to 5 mJ) triggers an electric discharge between a high voltage electrode and the laser ablated spot on the sample surface. Intense emission lines of neutral and singly-ionized atoms are observed with both spectroscopic techniques. However, lines of doubly-ionized atoms are detected with LA-SD-OES only. The line intensities of C III and Al III increase with decreasing laser pulse energy, surprisingly. The appearance of intense doubly-ionized lines indicates that the mechanisms of plasma excitation are different in LA-SD-OES compared to LIBS and that the combined plasma is not in local thermodynamic equilibrium at low laser energy. The calibration curves of Mn and Cr in industrial steel reveal steeper slope (higher sensitivity) for the Mn II and Cr II lines measured with LA-SD-OES and for the Mn I and Cr I lines measured with LIBS. Chemical imaging of the photoresist layer with LA-SD-OES at the atomic lines of C I and C III and the molecular band of CN reveals all details of the sample. Similar images are obtained for C I and CN using LIBS, however, no image contrast is obtained at the C III line. The very low pulse energy in LA-SD-OES enables soft sampling and may be beneficial also for the analysis and imaging of sensitive material.

中文翻译：

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通过激光烧蚀-火花放电-光发射光谱 (LA-SD-OES) 和激光诱导击穿光谱 (LIBS) 分析钢中的微量元素和微图案聚合物的化学成像

摘要 激光烧蚀 - 火花放电 - 光发射光谱 (LA-SD-OES) 和激光诱导击穿光谱 (LIBS) 用于分析钢中的微量元素锰 (Mn) 和铬 (Cr) 以及用于化学成像微图案光刻胶层。在 LA-SD-OES 中，弱激光脉冲（典型能量为 50 μJ 至 5 mJ）触发高压电极和样品表面的激光烧蚀点之间的放电。两种光谱技术都可以观察到中性原子和单电离原子的强发射线。然而，双电离原子线只能用 LA-SD-OES 检测。令人惊讶的是，C III 和 Al III 的线强度随着激光脉冲能量的降低而增加。强烈双电离线的出现表明，与 LIBS 相比，LA-SD-OES 中的等离子体激发机制不同，并且组合等离子体在低激光能量下不处于局部热力学平衡。工业钢中 Mn 和 Cr 的校准曲线显示，使用 LA-SD-OES 测量的 Mn II 和 Cr II 谱线以及使用 LIBS 测量的 Mn I 和 Cr I 谱线具有更陡峭的斜率（更高的灵敏度）。使用 LA-SD-OES 在 CI 和 C III 原子线以及 CN 分子带处对光刻胶层进行化学成像，揭示了样品的所有细节。使用 LIBS 为 CI 和 CN 获得了类似的图像，但是，在 C III 线上没有获得图像对比度。LA-SD-OES 中的脉冲能量非常低，可实现软采样，也可能有益于敏感材料的分析和成像。