Application of electric field-assisted LIBS (EF-LIBS) for ultra-trace detection of chromium in aluminum alloys

Laser-Induced Breakdown Spectroscopy (LIBS) is a rapid, nondestructive technique for elemental analysis, but its sensitivity is often limited for ultra-trace detection in metallic matrices. In this study, electric field-assisted LIBS (EF-LIBS) was employed to enhance chromium (Cr) detection in aluminum alloys containing 10–50 ppm Cr. A Q-switched Nd: YAG laser (532 nm) was used, and an external electric field of 49–120 V/mm was applied across the plasma plume. The influence of the electric field on emission intensity, signal stability, plasma temperature, and electron number density was systematically investigated. EF-LIBS produced mean enhancement factors of 3.98 ± 0.36 for neutral lines and 14.56 ± 1.05 for ionic lines, while the relative standard deviation decreased from