Investigation of the laser-induced breakdown plasma, acoustic vibrations and dissociation processes of water molecules caused by laser breakdown of colloidal solutions containing Ni nanoparticles

In this work the process of optical breakdown under laser irradiation by nanosecond pulses with an energy of 650 mJ of aqueous solutions of Ni nanoparticles is investigated. A monotonic change in the number of breakdowns, the average distance between closest breakdowns, the average plasma size of an individual breakdown, the luminosity of a plasma flash, the intensity of acoustic signals, and the rate of formation of dissociation products-O-2, H-2, OH center dot, and H2O2 with an increase in the irradiation time was established. With an increase in the concentration of nanoparticles, the measured values change non-monotonically. The maximum luminosity of a plasma flash is observed at a nanoparticle concentration of 10(9) NP ml(-1) and 10(10) NP ml(-1) and reaches 350 cd m(-2). The maximum pressure at the shock front is 1.5-2 MPa at a nanoparticle concentration of 10(10) NP ml(-1). The maximum rates of generation of O-2, H-2, OH center dot and H2O2 are observed at concentrations of 10(9) NP ml(-1) and 10(10) NP ml(-1). Correlation analysis of the studied physicochemical phenomena shows that the formation of molecular gases is associated with acoustic processes, and the formation of radical products and hydrogen peroxide correlates with the physicochemical properties of plasma.

Automated summary

The study investigates the optical breakdown process under laser irradiation by nanosecond pulses with energy of 650 mJ in aqueous solutions of Ni nanoparticles. It was found that various parameters such as the number of breakdowns, plasma size, luminosity, acoustic signals, and formation rates of dissociation products change monotonically with irradiation time. Additionally, the measured values change non-monotonically with an increase in nanoparticle concentration.