Elemental detection of jades with reduced sample damage by target-enhanced orthogonal double-pulse LIBS using surface micro-structured copper target

Reduced sample damage is necessary when sensitive elemental analysis is carried out on precious samples. High analytical sensitivity and reduced sample damage are contradictory in the conventional laser-induced breakdown spectroscopy (LIBS) analysis. To solve this problem, target-enhanced orthogonal double-pulse LIBS (TEODP-LIBS) in a reheating regime was developed in this work. A copper plate fabricated with periodic micro-structures on its surface using electroplating was used as the signal enhancement target. The presence of periodic micro-structures on the copper surface changes the laser–target and laser–plasma interactions, increasing both temperature and electron density of the plasma, thus being able to introduce about 2-folds secondary signal enhancement for the sample elements compared with the flat surface copper target. Xiuyan jade samples were analyzed experimentally. For minor element detection, the same level of signal intensity was detected via reheating TEODP-LIBS as that via single-pulse LIBS, but due to the selection of different pulse energies, a 19.6-fold reduction in sample damage was observed. This work demonstrated the possibility of using a surface micro-structured solid plate as the signal enhancement target in TEODP-LIBS to facilitate more sensitive elemental detection in solid samples. This technique is especially useful for the elemental analysis of precious samples, when reduced sample damage is required.