Experimental and molecular dynamics study of laser-induced carbon nanosphere formation using nanosecond-pulsed lasers

In this study, carbon nanospheres (CNSs) were synthesized using a 450 nm wavelength nanosecond-pulsed laser, and their formation mechanism was theoretically elucidated through molecular dynamics simulations. It was observed empirically that the size of the formed particles varied with the fluence. The formation mechanism was verified using molecular dynamics simulations. The simulation results showed that the sp³ hybridisation ratio was the highest within a specific temperature range, which was consistent with the three-dimensional carbon nanosphere formation observed in the experiments. In particular, the highest sp³/sp² ratio was noted at 4200 K, demonstrating that this temperature range is optimal for the stable growth of three-dimensional CNSs. However, at higher temperatures, the number of sp³ and sp² structures decreased, indicating that excessive temperatures hindered nanosphere formation. These results suggest that the size and structure of the CNSs can be controlled by adjusting the laser fluence, providing a fundamental basis for future applications of functional carbon-based nanospheres.