Effects of substrate heating on surface-enhanced laser-induced breakdown spectroscopy using porous silicon with low-energy laser.

Abstract

Surface-enhanced laser-induced breakdown spectroscopy (LIBS) using porous silicon (Si) has attracted attention as a technique for analyzing microvolume liquid samples with high sensitivity and precision. However, there remains a challenge in detection sensitivity for on-site applications of various samples. In this study, we combined a substrate heating method with LIBS using porous Si, and the resultant spectra were compared with those obtained without heating. A substrate with a dry residue of 100 ppm (mg L-1) copper (Cu) solution was analyzed using a nanosecond laser with a low energy of 1.0 mJ. The Cu signal intensity was enhanced over 3 times by substrate heating from 298 K to 573 K. This indicates that substrate heating is effective for further enhancing the LIBS signal in addition to the enhancement effect by porous structure. Plasma characteristics including plasma temperature, electron density, and emission region were also investigated to discuss the effects of substrate heating. The combination of porous Si and substrate heating would be an easily implemented technique for sensitivity improvement in surface-enhanced LIBS.

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