Single-shot dynamic TEM imaging of nanobubble formation and collapse

How can laser-induced bubble dynamics be explored under TEM?

Garth Egan, Edmond Lau, and Eric Schwegler from Lawrence Livermore National Laboratory published used their Hummingbird Scientific in-situ liquid flow TEM sample holder to investigate laser-induced bubble dynamics in water. The high frame rate of Movie-Mode Dynamic Transmission Electron Microscopy (MM-DTEM) was used to image bubbles created by exciting gold nanoparticles with a laser, which form and collapse in 10s to 100s of nanoseconds.

a) Example results from an experiment imaging three indicated bubbles. Each frame is labeled with respect to the peak of the initiating laser pulse. b) Diameters of the three bubbles, as labeled in (a), with time measured from average line profiles in the (c-e) average line profiles. f) DTEM data for isolated bubbled shifted so that t=0 occurs at the estimated maximum diameter, to normalize temporally around growth vs. collapse. Modeling results are shown in underlying color map. g) Bubble collapse times vs. bubble diameter for both isolated and interacting bubbles, shown with respect to the modeling results and Rayleigh relationship. Copyright © 2022 American Chemical Society

Au nanoparticles are excited using a 532 nm laser pulse (~12 ns) which nucleates bubbles. The beam-sensitive bubbles are imaged using a series of nine e-beam pulses (~10 ns), allowing time-resolved characterization of the growth and collapse dynamics. Asymmetric temporal profiles were consistent with modeling and literature data and indicated faster growth than collapse dynamics. The study reveals deeper insight into the complex interactions and behavior of bubbles forming in proximity to each other, combining liquid cell TEM with the high frame rates of DTEM in a novel experimental technique.

Reference: Garth Egan, Edmond Lau, and Eric Schwegler, Nano Letters 22 (3) 1053–1058 (2025) DOI: 10.1021/acs.nanolett.1c04101

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