Analysis of Cu and Zn contents in aluminum alloys by femtosecond laser-ablation spark-induced breakdown spectroscopy

Abstract To enhance the sensitivity of detecting Cu and Zn in aluminum alloys, we incorporated a spark discharge unit into the femtosecond laser-induced breakdown spectroscopy (fs-LIBS) system, forming a femtosecond laser ablation spark-induced breakdown spectroscopy (fs-LA-SIBS) system. We utilized both fs-LA-SIBS and fs-LIBS techniques to detect Cu and Zn in various aluminum alloy samples with different contents. Our results reveal that the spark discharge extends the duration of laser-induced plasma atomic radiation and amplifies the peak intensity of atomic radiation, thereby significantly increasing the time-integrated signal intensity of laser-induced plasma. Under the present experimental conditions, the limits of detection (LoDs) of Cu and Zn in aluminum alloy by fs-LA-SIBS are 16 and 12 ppm, respectively. In contrast, the LoDs of Cu and Zn by fs-LIBS technique under the same laser pulse energy are 96 and 84 ppm, respectively. Hence, for Cu, the LoDs by the fs-LA-SIBS technique are 1/6 of those by the fs-LIBS technique, and for Zn, the LoDs by the fs-LA-SIBS technique are 1/7 of those by the fs-LIBS technique. Our findings demonstrate that the fs-LA-SIBS technique is more sensitive than the fs-LIBS technique in the quantitative analysis of elements and may be a practical approach for elemental analysis in alloys.