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The ablation of Cd has been performed by employing Q-switched Nd: YAG 10 ns laser pulses with a central wavelength of 1064 nm for a pulsed energy of 200 mJ under various ambient environments of argon, air and helium. The optical emission spectroscopy of Cd plasma has been studied under different filling pressures of shield gases ranging from 5 torr to 760 torr using LIBS spectrometer system. The effect of different gases and their pressures on the intensity of spectral emission, electron temperature and density of the laser-produced plasma has been investigated. SEM analysis has been performed to investigate the dependence of surface morphological changes of an irradiated target on the nature and pressure of an ambient gas. A strong correlation has revealed the vital role of electron temperature and density of laser-induced plasma for the surface modification of Cd. These results strongly indicate that the nature and pressure of the ambient atmosphere is one of the controlling factors of the plasma characteristics, as well as the factors related to the laser energy absorption for surface modification.

The effect of different gases and their pressures on the intensity of spectral emission, electron temperature and density of laser-produced plasma has been investigated. For this purpose, Cu targets were ablated by employing Q-switched Nd:YAG laser pulses (λ∼1064 nm, τ∼10 ns, pulsed energy of 200 mJ) under various filling pressures of the background gases argon, air and helium. The optical emission spectroscopy of Cu plasma has been studied using the laser-induced breakdown spectroscopy system. The results obtained strongly indicate that the nature and pressure of the ambient atmosphere are one of the controlling factors of the plasma characteristics. A scanning electron microscopy analysis has been performed to investigate the dependence of surface morphological changes of an irradiated target on the nature and pressure of an ambient gas. The basic aim of this study is to improve the understanding of ablation mechanisms and plasma parameters (optical emission intensity, electron temperature and density) under various ambient conditions. The optimization of experimental conditions (the nature and pressure of the ambient environment) is very important for temperatures and densities of ablated species, which are consequently crucial for pulsed laser deposition of thin films and nanostructuring of materials.

The effects of laser treatment on the mechanical response of polycrystalline titanium (99.99%) have been investigated using the laser gas nitriding technique. Samples were subjected to irradiation by a 532 nm pulsed Nd:YAG laser for 100–400 shots. Laser pulses of energy 370 mJ with 10 Hz repetition rate were used to irradiate the surface of specimens and to activate the reaction between the irradiated surface and nitrogen. The effects of multiple laser pulses on the microstructure, yield stress (YS), ultimate tensile stress (UTS) and microhardness of the specimens were examined. Characterization of both the unirradiated and the irradiated specimens was carried out using a scanning electron microscope, an x-ray diffractometer and an energy dispersive x-ray spectrometer. The results show that irradiation of the specimens resulted in the growth of grains in the beginning and then their segregation as the number of laser shots was increased. An incorporation of nitrogen ions into the surface is also observed. The microhardness was found to increase with increasing laser shots, whereas changes in YS and UTS with laser shots were found to be anomalous.

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