This publication reports the use of cryo-electron microscopy (cryo-EM) to visualize nanobubbles in solution, which, in contrast to nanobubbles on surfaces have been notoriously difficult to detect. The authors, a group of scientists from the University of Washington in Seattle and Revalesio, successfully tested the technique with nitrogen nanobubbles generated by a chemical reaction between two carbon films. The cryo-EM images of the nanobubbles bubbles showed the same features as predicted by theory.

Link to the paper: Cryo-EM Visualization of Nanobubbles in Aqueous Solutions | Langmuir (acs.org)