Abstract The LIBS (Laser-Induced Breakdown Spectroscopy) method has already demonstrated its reliability and its robustness in many situations for the multi-elemental composition determination of samples. However, certain conditions prevent a totally satisfactory determination. For instance, the method is weakly efficient to measure with accuracy the light elements concentration in metallic matrices. Since the laser pulse used to produce the plasma contributes to its heating, using an additional pulse (double pulse configuration) provides the increase in electron temperature and density without additional ablation. A better signal-to-noise ratio and a lower limit of detection can be reached. The present paper reports the results of different experiments performed to quantify the modifications induced (1) on the electron density by the second laser pulse in a preformed aluminum plasma, and (2) on the second laser pulse itself. The related experiments have been done in the case where the plasma is produced by a picosecond laser pulse and the second laser pulse is of the nanosecond type. The electron density reaches a maximum resulting from the total ionization of the aluminum plasma volume irradiated by the second laser pulse.

中文翻译：

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皮秒激光诱导的预制铝等离子体对纳秒激光脉冲的吸收

摘要 LIBS（激光诱导击穿光谱）方法已经证明了其在多种情况下对样品多元素组成测定的可靠性和稳健性。然而，某些条件阻止了完全令人满意的测定。例如，该方法无法准确测量金属基质中的轻元素浓度。由于用于产生等离子体的激光脉冲有助于其加热，因此使用附加脉冲（双脉冲配置）可增加电子温度和密度，而无需额外烧蚀。可以达到更好的信噪比和检测下限。本文报告了不同实验的结果，用于量化 (1) 在预制铝等离子体中第二个激光脉冲对电子密度引起的修改，以及 (2) 对第二个激光脉冲本身的修改。在等离子体由皮秒激光脉冲产生并且第二激光脉冲为纳秒类型的情况下进行了相关实验。由于第二激光脉冲照射的铝等离子体体积的总电离，电子密度达到最大值。