Investigation of silver plasma and surface morphology from a nanosecond laser ablation

Silver was irradiated both in air at normal atmospheric pressure as well as in vacuum (∼10−6 Torr) with a Q-switched Nd:YAG laser of wavelength 1.064 μm, pulse energy 10 mJ and pulse duration 9–14 ns. The silver plasma plume dynamics was investigated using CCD camera. Harmonic generation of Nd:YAG laser and Bremsstrahlung radiations from silver plasma were studied. The surface morphology of the irradiated specimens was examined using metallurgical microscope. The damages produced on the target surface due to interaction of laser pulses were in the form of sputtering, ejection of particles, craters and ripple formation. It was observed that in air collisional sputtering, crater formation, ripples and bubble formation were dominant, while in vacuum hydrodynamic sputtering and exfoliational sputtering were playing their role.