Optimal laser fluence for pulsed laser ablation synthesis of silicon nanoparticles in liquid

In this study, we identified the optimal laser fluence range for the synthesis of optically relevant silicon nanoparticles (SiNPs) via femtosecond pulsed laser ablation in liquid (fs-PLAL). We used optimization via minimization to extract total nanoparticle population and concentration from UV-Vis absorption spectrum, and compared them to both single- and multiple-pulse ablation crater volumes. The optimal fluence between 20-30 J/cm² is found to maximize SiNP yield and minimize beam loss caused by persistent bubbles. A systematic analysis of ablation volumes showed that while single-pulsed crater volume increased with fluence, both multi-pulsed ablation volumes and measurable SiNP volumes peak near 25 J/cm² before decreasing. This drop is due to the formation of persistent cavitation bubbles that scatter incoming pulses and reduce ablation efficiency. The peak nanoparticle synthesis yield was ∼ 0.311 <i>μ</i>g/min, which is comparable to the literature values. Importantly, this yield value is expected to be further improved by using high-speed scanning systems (e.g., galvo mirrors) to reduce pulse overlap and avoid cavitation bubble interference. These findings offer practical guidance for tuning PLAL parameters in future high-throughput, optically tuned SiNP production.