Nanometric range depth-resolved analysis of coated-steels using laser-induced breakdown spectrometry with a 308 nm collimated beam

The spatial profile from an XeCl excimer laser was modified using a simple two-lenses telescope to generate a flat energy-profile beam that impinged a layered sample (a Zn-coated steel) without beam conditioning. The irradiance obtained (about 10(7) W cm(-2)) was high enough to vaporize the target, to cause plasma formation and to allow atomic emission spectrometry with acceptable signal-to-noise ratio. Modification in beam energy distribution resulted in flat ablated profiles and improved depth-resolution up to the few nm pulse(-1) range was attained. The net intensity areas were transformed into normalized values leading to plots in excellent agreement with those provided by commercial depth-resolved analysis instruments.