The application of laser-induced plasma emission spectrometry to the depth profile measurement of coatings on steel is examined. The effects of key experimental parameters, such as laser energy and sample position relative to the laser focal point, on depth profile performance were characterized for a Zn/Ni coating on steel. With preferred operating conditions, linear calibrations against coating thickness for Zn/Ni (2.7 to 7.2 μm) and Sn (0.38 to 1.48 μm) on steel were achieved with good precision (3.5% relative standard deviation). An ultra-thin coating of Cr (20 nm) on steel was also detected by the technique. The depth profile performance and rapid measurement times, typically less than 60 s, indicate that the technique may be useful in industrial applications.
David R. Anderson, Cameron W. McLeod, Tim English, and A. Trevor Smith, "Depth Profile Studies Using Laser-Induced Plasma Emission Spectrometry," Appl. Spectrosc. 49, 691-701 (1995)