Investigation of the exuberant cavitation bubble and shock wave dynamics in pulsed laser ablation of copper in distilled water

Pulsed laser ablation in liquid is a very efficient technique for the synthesis of nanoparticles in colloidal form. In order to maximize the applicability of this technique, it is imperative to understand the dynamics of the underlying phenomena like the generation of cavitation bubbles and shock waves. Hence, in the present work, the dynamics of the cavitation bubbles and shock waves produced during pulsed laser ablation of copper in distilled water is investigated. Two techniques, the shadowgraphy and the beam deflection have been used to characterize these phenomena. The shadowgraphs reveal that in the initial stage, the bubble grows upto a maximum size after which it compresses. It is also observed that the bubbles exhibit secondary oscillations at higher laser fluence. The results obtained for the cavitation bubbles using the beam deflection technique matches well with those obtained by the shadowgraphy technique. Two fluid dynamical models, the modified Rayleigh-Plesset and the Gilmore model have been applied to the temporal evolution data of the bubble obtained from the shadowgraphs to analytically derive the thermodynamical properties of the bubble. Again, the beam deflection technique is applied to study the dynamics of the shock waves and the associated thermodynamics is evaluated by considering its propagation. The extreme high values of pressure and temperature derived at the interface of copper and distilled water can be applied to understand the nucleation of nanoparticles.