Explosive Formation and Dynamics of Vapor Nanobubbles around a Continuously Heated Gold Nanosphere

TL;DR

This study investigates the rapid formation, dynamics, and stability of vapor nanobubbles around a heated gold nanoparticle, revealing echo signatures and potential applications in optical modulation and photoacoustic imaging.

Contribution

It demonstrates controlled formation and stability of vapor nanobubbles with echo signatures, advancing understanding of their dynamics and potential technological uses.

Findings

Vapor nanobubbles form rapidly around heated gold nanoparticles.

Echo signatures from sound waves are observed and can trigger new explosions.

Stable nanobubbles with vapor shells can be maintained with proper heating profiles.

Abstract

We form sub-micrometer-sized vapor bubbles around a single laser heating gold nanoparticle in a liquid and monitor them through optical scattering of a probe laser. The fast, inertia-governed expansion is followed by a slower contraction and disappearance after some tens of nanoseconds. In a narrow range of illumination powers, bubble time traces show a clear echo signature. We attribute it to sound waves released upon the initial explosion and reflected by flat interfaces, hundreds of microns away from the particle. Echoes can trigger new explosions. A steady state of nanobubble with a vapor shell surrounding the heated nanoparticle can be reached by a proper time profile of the heating intensity. Stable nanobubbles could have original applications for light modulation and for enhanced optical-acoustic coupling in photoacoustic microscopy.