Detection of trace substances adhered to a metal surface by laser-induced breakdown spectroscopy

Abstract

Laser-induced breakdown spectroscopy (LIBS) was applied to inspect trace substances on aluminum alloy surfaces. Silicone oil, which is often used as a release agent, was employed as the adhered substance. Nanosecond laser pulses at UV wavelengths (KrF laser, λ = 248 nm) were employed for the LIBS measurements. Although the absorption of silicone oil at 248 nm was negligible, the Si emission of surface-adhered silicone oil was detected. The intensity ratio of the Si emission at 288 nm to the Al emission at 309 nm increased with increasing surface concentrations in the range 1–35 μg cm⁻², and a linear dependence on the silicone oil surface concentration was observed at low surface concentrations (<5.0 μg cm⁻²). The limit of detection was evaluated to be 1.18 μg cm⁻².