Synergistic influence of external electric field on laser ablation in liquid: correlating nanoparticle synthesis and cavitation bubble dynamics

Abstract

The present study aims to investigate the changes in the properties of nanoparticles (NPs) and cavitation bubble dynamics on applying an external electric field during laser ablation in liquid (LAL). Investigating electric field assisted laser ablation in liquid (EFLAL) is crucial since phenomena such as plasma charging effect and electrostatic pressure have important role in determining the size, shape, and crystallinity. of the NPs. With this motivation, the present study has been conducted with different electric fields of 0, 100, 500 and 1000 V/cm to probe the effect of an external electric field on the dynamics of EFLAL. The charging effect observed on NPs during cavitation bubble dynamics was also investigated at these field intensities. The size of NPs witnesses a reduction from ~30 nm without electric field to ~19 nm in presence of electric field. Also, a significant narrowing of the size distribution by over 4 times was observed in the presence of electric field. This clearly demonstrates that EFLAL can be used to obtain NPs with uniform size distribution. Moreover, NPs of different shapes have also been observed by varying the electric field intensities (100 and 1000 V/cm). The effect of the external electric field on the dynamics of the cavitation bubble produced during EFLAL has been probed using shadowgraphy technique. It has been observed that the bubble size increases with the presence of an electric field. The estimation of the bubble pressure in the presence of an electric field has revealed that the implosion bubble pressure is significantly lower than pressure in the absence of the field. The results obtained for NPs have been correlated to the changes in bubble parameters in this work.