With NASA’s Perseverance rover and CNSA’s Zhurong rover working on Mars, Laser-induced breakdown spectroscopy (LIBS), as the future superstar of analytical atomic spectrometry, gets more and more attention worldwide. It has been applied in many fields, including metallurgy, energy, environment monitoring, advanced manufacturing, biomedicine, and Mars exploration due to its advantages of simple sample preparation, in-situ, rapid, and multi-elemental detection.
At present, the good quantitative accuracy of LIBS generally dependsonthestandard samples. However, it is challenging to meet this requirement for samples of unknown composition, such as cultural relics and biological tissues. The only solution istheCF-LIBS technology, which requires no standard sample and can directly determine elemental concentrations using the Boltzmann-Saha distribution relationship in the laser-induced plasma. However, the quantitative accuracy of CF-LIBS is often affected by the self-absorption effect. Researchers usually adopt various self-absorption correction algorithms to compensate for the self-absorption to improve the accuracy of CF-LIBS.
A new CF-LIBS method based on exploiting self-absorption (CF-LIBS with CD-SRL) was recently proposed by Prof. Lianbo Guo’s groupfrom Wuhan National Laboratory for Optoelectronics (WNLO), which combined the optical depth method for plasma diagnosis with CF-LIBS based on the standard reference line. In this method, the Columnar Density Saha-Boltzmann plot was used to evaluate the plasma temperature accurately. Elemental absolute concentration in samples could be calculated by columnar densities of self-absorbed lines and intensities of selected standard reference lines. The quantitative results of typical alloy samples showed that the proposed method has higher quantitative accuracy, manoeuvrability and execution efficiency than the traditional CF-LIBS based on the Boltzmann plot. This method maintains the advantages of the traditional CF-LIBS method without the need for standard samples. It does not require the self-absorption iterative correction algorithm and can directly use the self-absorbed line in the LIBS spectrum to perform calibration-free analysis. Its high execution efficiency and good quantitative performance are expected to promote LIBS’s further popularization and practical application.
Fig.1. The main principle of the proposed method and the improvements of quantitative analysis
This research was recently published in Analytica Chimica Acta. The first author is Zhenlin Hu as a PhD candidate. The co-corresponding authors are Prof. Lianbo Guofrom Wuhan National Laboratory for Optoelectronics (WNLO) and Ass. Prof. Yun Tangfrom Hunan University of Science and Technology. Feng Chen, Deng Zhang, Yanwu Chu, and Weiliang Wang participated in relevant work as co-authors. The first affiliation is WNLO, Huazhong University of Science and Technology. This research was financially supported by the National Natural Science Foundation of China (No. 62075069, 62005078, and 61575073).
Paperlink:https://doi.org/10.1016/j.aca.2021.339008
Reference:Z. Hu, F. Chen, D. Zhang, Y. Chu, W. Wang, Y. Tang *, L. Guo *, "A method for improving the accuracy of calibration-free laser-induced breakdown spectroscopy by exploiting self-absorption", Analytica Chimica Acta, 1183, 339008 (2021)
