Wei Bingyu, Yang Chen, Wu Shujia, Xiang Yulin, Wang Zexuan, Sun Shaohua, Hu Bitao, Liu Zuoye
Frontiers Science Center for Rare Isotopes, Lanzhou University, Lanzhou, 730000, China; School of Nuclear Science and Technology, Lanzhou University, Lanzhou, 730000, China.
Frontiers Science Center for Rare Isotopes, Lanzhou University, Lanzhou, 730000, China.
Anal Chim Acta. 2024 Nov 1;1328:343183. doi: 10.1016/j.aca.2024.343183. Epub 2024 Aug 30.
Laser-induced breakdown spectroscopy (LIBS) is a versatile analytical technique for element determination in solids, liquids, and gases. However, LIBS suffers from low detection sensitivity and high relative standard deviation (RSD), restricting its large-scale applications. the process of a physical sampling can, in some cases, compromise the mechanical strength of the component under examination. It should be considered that too large laser energy is bound to cause damage to samples which cannot be tolerated in the process of safe production in the nuclear industry. It is necessary to find a method to obtain high elemental signal intensity in low energy laser.
Here, we present a novel approach by integrating microwave plasma torch (MPT) with LIBS, referred to as MPT-LIBS, which effectively addresses the limitations associated with traditional LIBS. The MPT-LIBS technique is evaluated using Cu samples with a low laser pulse energy of 0.55 mJ. A remarkable enhancement factor of over 70 for Cu I 521.82 nm line is demonstrated, while that of Cu I 324.75 nm and 327.40 nm lines exceeding two orders of magnitude. Furthermore, the RSDs of all Cu spectral lines are reduced, especially for Cu I 521.82 nm, which is decreased from 11.48 % to 1.36 %. This indicates a significant improvement in signal stability. Characterization of the tested samples using con-focal microscopy reveals that the ablation area of MPT-LIBS is only 1.36 times of that of LIBS. The limit of detection of Cu I 324.75 nm line is reduced from 52.8 ppk to 319 ppm.
This study not only offers valuable guidance for improving signal stability and the limit of detection in LIBS, but also demonstrates minimal sample damage due to its low ablation amount. Consequently, the proposed methodology has the potential to significantly advance LIBS technology, expanding its applicability in industrial applications.
激光诱导击穿光谱技术（LIBS）是一种用于测定固体、液体和气体中元素的通用分析技术。然而，LIBS存在检测灵敏度低和相对标准偏差（RSD）高的问题，限制了其大规模应用。在某些情况下，物理采样过程可能会损害被检测部件的机械强度。还应考虑到，过大的激光能量必然会对样品造成损害，这在核工业安全生产过程中是无法容忍的。因此，有必要找到一种在低能量激光下获得高元素信号强度的方法。
在此，我们提出了一种将微波等离子体炬（MPT）与LIBS相结合的新方法，称为MPT-LIBS，它有效地解决了传统LIBS的局限性。使用低激光脉冲能量为0.55 mJ的铜样品对MPT-LIBS技术进行了评估。结果表明，Cu I 521.82 nm谱线的增强因子超过70，而Cu I 324.75 nm和327.40 nm谱线的增强因子超过两个数量级。此外，所有铜光谱线的RSD均降低，特别是Cu I 521.82 nm谱线，从11.48%降至1.36%。这表明信号稳定性有了显著提高。使用共聚焦显微镜对测试样品进行表征，结果表明MPT-LIBS的烧蚀面积仅为LIBS的1.36倍。Cu I 324.75 nm谱线的检测限从52.8 ppk降至319 ppm。
本研究不仅为提高LIBS的信号稳定性和检测限提供了有价值的指导，而且由于其低烧蚀量，样品损伤最小。因此，所提出的方法有可能显著推动LIBS技术的发展，扩大其在工业应用中的适用性。
