Mechanism of Laser‐Induced Self‐Deposition of Nanoparticles Identified by In Situ Observation

Abstract Laser ablation has emerged as a promising technique for fabricating nanoparticles (NPs) on metal surfaces, as demonstrated by extensive experimental and simulation studies. However, the fundamental mechanisms underlying the self‐deposition of laser‐induced NPs remain unclear, owing to the complexity of the process influenced by various factors and their interactions. In contrast to prior research that solely focused on isolated factors, this research proposes an observation system designed to systematically elucidate the mechanisms of laser‐induced self‐deposition of NPs on a copper surface. This system integrates ultrashort exposure observation with the pump–probe method, enabling the capture of dynamically evolving phenomena within the time frame of laser ablation. The proposed probing techniques reveal that the plasma plume consistently aligns with the NP spatter boundary. Additionally, liquid NPs are observed to travel into the plume and evaporate at its boundary, while solid NPs are propelled in opposite directions owing to recoil pressure from jetting vapor, eventually settling around the laser‐irradiated area. This study offers comprehensive insights into the mechanisms of NP self‐deposition through laser ablation, which is critical for optimizing the laser parameters in micro/nanofabrication and advancing the fundamental research in laser manufacturing.