INVESTIGATION OF LASER INDUCED PLASMA OF LAYERED TARGETS

Abstract

Laser-induced breakdown spectroscopy (LIBS) is a relatively novel technique that is being applied to the characterization of interfaces in layered materials as an alternative to other classic surface analytical techniques. The composition of each individual layer, particularly at the interface, which is available from a depth profile, is much more informative than the composition of one layer in addition to the exact location of the interface. In the present work the change of laser irradiance at its fundamental wavelength {A = 1064 nm) by changing the working distance (WD), which is the difference between the lens­ to-sample distance and the focal length of the lens, has been found to be a very critical parameter. The effect of changing WD on the intersection point, the ablation rate and crater depth of Au, Ag and Zn thin films onto Cu substrates has been studied by using 50rnJ, Nd: YAG laser pulses. The experimental findings, obtained with fixed experimental set-up, showed that lowering the irradiance, the intersection point (number of laser pulses that needed to reach the interface), while the average ablation rate and the crater depth are decreasing. Moreover the possibility of employing relatively high energy laser pulses for depth profiling analysis has been demonstrated. Optical microscopic studies for the produced craters of the layered targets were examined. The plasma parameters (electron temperature and electron density) also have been studied.