Cavity formation dynamics in gold nanoparticles (10–50 nm) upon femtosecond laser irradiation

Abstract The geometric parameters of nanoparticles can be modified and controlled through irradiation with femtosecond laser pulses at the localized surface plasmon resonance (LSPR). Previous work has shown that under specific conditions of laser fluence, pulse duration, particle size, and the thermal properties of the solvent, hollow gold nanospheres can form when solid gold nanospheres are irradiated. In this article, we explore these conditions for a range of nanoparticle sizes (10–50 nm) of practical interest towards applications in an aqueous solvent using molecular dynamics simulations. Laser energy deposition is simulated by heating the particle from 300 K to 3000 K, followed by cooling to room temperature using a Langevin thermostat, which mimics an implicit solvent. We investigate the structural dynamics of the particle during both heating and cooling processes upon irradiation with a single femtosecond laser pulse. Our results indicate that an in silico methodology can be established to guide the synthesis of nanoparticles with tailored geometric properties. We analyse the aspect ratio, cavity size, and relative size changes both at the final state and throughout the dynamic process. Our findings contribute to efforts towards supporting applications in energy, environmental, and biomedical fields.