Towards an Improved Understanding of the Evolution of the Size Distribution of Ultrafine Nanoparticles Produced by a Rapidly Quenched Vapor Source

In this study, we explore the evolution of the size distribution of Ag nanoparticles produced by a spark ablation vapor source. The as-prepared Ag nanoparticles exhibit a special bimodal lognormal size distribution, containing both ultrafine (~ 1.5 nm) and larger (3 to 15 nm) particles. Such a size distribution differs from previous investigations of nanoparticles generated by spark ablation, which had larger particles with a lognormal distribution. The 1.5 nm size of the ultrafine Ag nanoparticles in this study is close to the theoretical size of the critical nucleus predicted by classic nucleation theory. By considering the simultaneous precipitation and coagulation of the particles and different coalescence dynamics at different sizes, we established a quantitative model that describes the evolution of the special size distribution of the Ag nanoparticles. The model’s predictions accurately reproduce the as-measured nanoparticle size distribution. This study can provide a new experimental and theoretical basis for understanding the kinetics of the growth of ultrafine nanoparticles produced by a rapidly quenched vapor source.