Abstract Stability of acoustic levitated water droplets, for laser induced breakdown spectroscopy (LIBS), is required in order to obtain shot-to-shot reproducibility and low limits of detection. Although stabilization is possible by increasing the TinyLev levitator's operational voltage, at high voltages liquid droplets shatter when inserted at the nodes of the acoustic levitator. An alternative for stabilization, it is the use of a four beam laser arrangement, similar to an optical trap. In this case, we have found adequate not to use focusing lenses, since the goal is just to exert certain lateral pressure to counteract the lateral pressure instabilities generated by the acoustic levitator and simplify the optical arrangement. For an operational voltage of 8.5 V, a reduction on the droplet's horizontal deviation of 42% is attained at 650 mW laser power. At these experimental conditions, LIBS measurements were conducted on water samples doped with different metals. It is shown that, at this droplet's deviation, it is possible to analyze liquid samples despite a complete liquid evaporation is not reached. For Al samples a limit of detection (LoD) of 0.22 ppm is calculated from a calibration curve, and LoD of 1.18, 0.15, 0.94 and 0.7 ppm for Cu, Mn, Pb and Ni respectively, are estimated by signal to noise ratios values. These results show that even though, the final size of the liquid droplets is large, there is not a reduction on the lowest detectable concentration obtained, compared to other LIBS works on liquid samples. Leading up to conclude that pre-concentration effect takes more relevance than residual liquid's detrimental effect.

中文翻译：

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用于激光诱导击穿光谱的 TinyLev 声学悬浮器悬浮的水滴稳定性评估

摘要 对于激光诱导击穿光谱 (LIBS)，声学悬浮水滴的稳定性是必需的，以获得逐次重复性和低检测限。虽然可以通过增加 TinyLev 悬浮器的工作电压来实现稳定，但在高电压下，当液滴插入声悬浮器的节点时会破碎。另一种稳定的方法是使用四光束激光器排列，类似于光阱。在这种情况下，我们发现不使用聚焦透镜就足够了，因为目标只是施加一定的侧向压力来抵消声悬浮器产生的侧向压力不稳定性并简化光学布置。对于 8.5 V 的工作电压，液滴的减少 在 650 mW 激光功率下达到 42% 的水平偏差。在这些实验条件下，LIBS 测量是在掺杂不同金属的水样上进行的。结果表明，在这个液滴的偏差下，尽管没有达到完全的液体蒸发，也可以分析液体样品。对于 Al 样品，根据校准曲线计算出的检测限 (LoD) 为 0.22 ppm，而 Cu、Mn、Pb 和 Ni 的 LoD 分别为 1.18、0.15、0.94 和 0.7 ppm，通过信噪比值估计。这些结果表明，尽管液滴的最终尺寸很大，但与其他 LIBS 对液体样品的研究相比，获得的最低可检测浓度并没有减少。得出的结论是，预浓缩效应比残留液体更具相关性”