Dynamic Characterization of Nanomaterials Using Acoustic Levitator

Acoustic levitation provides a platform to trap and hold a small amount of material by using standing pressure waves and obviates the need of a container. The technique has a potential to be used for experiments that utilize a combination of laser and x-ray beams; x-ray scattering and laser distortion from the container can be avoided, sample consumption can be minimized, and unwanted chemistry that may occur at the container interface can be avoided. In an effort to integrate acoustic levitator into small angle X-ray scattering (SAXS) experiment at Advanced Photon Source (APS), a solution of gold nanoparticles has been dispensed and trapped into acoustic levitator for the time-resolved characterization of the nanoparticles. Results showed good reproducibility and a cumulative damage mechanism, likely due to the laser removal of the ligands from the nanoparticles. In another experiment, gold nanoparticles have been synthesized in the acoustically levitated droplets. Two microdispensers were employed to inject the solutions, a gold precursor (HAuCl₄) and a reducing agent (NaBH₄), into the levitator for mixing and synthesis of nanoparticles. SAXS was used for real-time characterization of nanoparticles formation.