Laser-induced breakdown spectroscopy using a porous silicon substrate produced by metal-assisted etching: microanalysis of a strontium chloride aqueous solution as an example

• Published in: Journal of analytical atomic spectrometry Vol. 35; no. 1; pp. 2239 - 2247
• Main Authors: Matsumoto, Ayumu, Shimazu, Yusuke, Yoshizumi, Sakiko, Nakano, Haruka, Yae, Shinji
• Format: Journal Article
• Language: English
• Published: London Royal Society of Chemistry 2020
• Subjects: Aqueous solutions; Chlorides; Etching; Laser induced breakdown spectroscopy; Lasers; Nanoparticles; Porous silicon; Residues; Silicon substrates; Spectroscopy; Spectrum analysis
• ISSN: 0267-9477; 1364-5544
• DOI: 10.1039/d0ja00144a

Laser-induced breakdown spectroscopy (LIBS) of dry residues on a solid substrate is a promising method for microanalysis of liquid samples. In this work, a hydrophilized porous silicon (Si) substrate loaded with gold nanoparticles was applied in LIBS of dry residues for signal enhancement. The porous Si substrate was prepared by a simple wet process, i.e. metal-assisted etching. A 5 μL strontium chloride aqueous solution was dried on the porous Si substrate and the dry residue was analyzed by a single-pulse scheme with a laser energy of 1.5 mJ per pulse. We successfully enhanced the strontium signal intensity over 150 times by using the porous Si substrate instead of a flat Si substrate. We also demonstrated that the signal intensity changed depending on the pore depth of the porous Si. The porous Si has great potential as a substrate for LIBS of dry residues. The LIBS signal of the dry residue from a small amount of liquid sample is significantly enhanced by using a porous silicon substrate produced by gold-nanoparticle-assisted etching.