Determination of chlorine in concrete by laser-induced breakdown spectroscopy in air

Abstract

The destruction of concrete is often associated with local chloride corrosion. The ability to determine by laser-induced breakdown spectroscopy (LIBS) the level of chlorine in concrete below that resulting in destructive material changes was demonstrated. The intensity of the analytical line Cl I 837.60 nm increased significantly with the use of double-pulse LIBS. The effects of the interpulse delay and the plasma observation time after the second pulse were studied in order to combine the second harmonics of Q-switched Nd:YAG and Nd:YALO lasers (532 nm + 540 nm). The optimal temporal parameters of double-pulse LIBS determination of chlorine were 4.0 and 0.5 μs, respectively. Under these conditions, the detection limit of chlorine was 50 ppm.