Multiframe Imaging of Micron and Nanoscale Bubble Dynamics.

Area of Science:

• Physics
• Materials Science
• Nanotechnology

Background:

• Laser-induced cavitation is a key phenomenon in various scientific fields.
• Understanding bubble dynamics at the nanoscale is crucial for many applications.
• Previous studies often relied on indirect methods to observe bubble collapse.

Purpose of the Study:

• To directly image the dynamic process of laser-induced cavitation of micron and nanoscale bubbles.
• To investigate the growth and collapse timescales of these bubbles.
• To observe the influence of bubble proximity on cavitation dynamics.

Main Methods:

• Utilized Movie-Mode Dynamic Transmission Electron Microscopy (MM-DTEM) for high-speed imaging.
• Employed a 532 nm laser pulse to excite gold nanoparticles in a thin water layer.
• Captured sequential images using nine electron pulses with inter-pulse timings as short as 40 ns.

Main Results:

• Observed isolated nanobubbles collapsing in less than 50 ns.
• Documented larger bubbles (2-3 μm) growing and collapsing in under 200 ns.
• Noted asymmetric temporal profiles suggesting faster bubble growth than collapse.
• Observed complex interactions between nearby bubbles, leading to extended lifetimes and rebound.

Conclusions:

• MM-DTEM provides direct, high-resolution visualization of laser-induced bubble cavitation.
• Bubble collapse dynamics are rapid, with timescales consistent with theoretical models.
• Interactions between bubbles significantly alter their collapse and rebound behavior.