Plasmonic Supercavitation Enables Nanoparticle Photo-Ejection Across Air/Water Interface.

Area of Science:

• Nanotechnology and Materials Science
• Optical Physics
• Fluid Dynamics

Background:

• Separating miniscule solid particles, such as nanoparticles, from liquids is crucial for diverse applications.
• Capillary forces at the liquid interface pose a significant challenge, preventing easy nanoparticle removal using conventional methods.

Purpose of the Study:

• To demonstrate a novel method for ejecting metallic nanoparticles from liquid media.
• To investigate the underlying physical mechanisms enabling nanoparticle separation from liquids.
• To explore potential applications of this nanoparticle separation technique.

Main Methods:

• Utilized laser excitation to apply optical force, driving nanoparticles towards the liquid surface.
• Induce intense local heating of nanoparticles, forming a nanoparticle-encapsulating nanobubble (supercavitation).
• Employed transient scattering experiments and molecular dynamics simulations to validate the mechanism.

Main Results:

• Successfully demonstrated the expulsion of metallic nanoparticles from liquid using laser-induced supercavitation.
• Confirmed that the nanobubble formation effectively overcomes trapping forces at the liquid/air interface.
• Showcased nanoparticle deposition onto a solid surface for subsequent applications, such as 2D material fabrication.

Conclusions:

• A fundamental mechanism for separating nanoparticles from liquids via laser-induced supercavitation has been revealed.
• The developed technique offers a promising approach for nanoparticle separation, nanomaterial synthesis, and biomedical applications.
• This method effectively addresses the limitations imposed by capillary forces in nanoparticle manipulation.