Aerosol generation from laser-ablation-synthesized nanoparticles

The synthesis of nanomaterials through pulsed-laser ablation of a bulk solids can be applied for the generation of reference aerosols for applications in aerosol science, where no reliable source of reference aerosol samples currently exists. To develop aerosol generators based on laser ablation that are capable of reliable aerosol generation with well-defined properties, more data is needed on how the aerosol properties depend on the laser ablation parameters, such as wavelength, power, repetition rate, and surrounding gas. We present an aerosol generation device based on laser ablation from a nanosecond pulsed Nd:YAG laser and report initial data from our systematic study of the effect of ablation parameters on aerosol formation from different metals and graphite. The size and concentration distribution of the resulting laser-ablation-generated aerosols were measured using a scanning mobility particle sizer. The primary nanoparticles formed in the ablation chamber directly as a result of ablation were collected and imaged using scanning electron microscopy and compared to the ensuing aerosols formed after agglomeration of the nanoparticles. We found that the aerosol size and concentration increases with increasing laser irradiance and increasing repetition rate. Different gases were used for the aerosol generation, and our results shed light on how the plasma development and resulting nanoparticle formation depend on the gas environment. Certain metal aerosols formed in a synthetic air environment were larger and more concentrated than in argon and nitrogen. The charge of the aerosols was also monitored using a parallel plate capacitor.