Cross-sectional Observation of Micro- and Nanobubbles Formed In-situ in a Scanning Electron Microscope

Abstract

Surface micro- and nanobubbles were formed in situ using a conventional scanning electron microscope by radiolysis of water confined in liquid cells with electron-transparent windows. The shapes and contact angles of the bubbles formed at the window corner were directly measured using a scanning electron microscope. All the observed contact angles were close to 90°, regardless of the size, indicating that the corner bubbles had shapes that almost maximized the Laplace pressure. Bubble formation far from the electron irradiation site was also analyzed using a Monte Carlo simulation.