Scientists 'see' nanoscale forces, providing evidence of electric fields at the air‑water interface
Bubbles are round, and we know surface tension does that. But squeeze that gas-liquid boundary into a space only a few tens of nanometers wide—could other forces be at work?
Scientists have observed electric fields at the air-water interface at the nanoscale, providing evidence for forces that were previously debated. This discovery could explain why reactions in tiny droplets occur faster than in bulk water. Researchers from Kyushu University, Nankai University, Stanford University, and the University of Alberta used 3D transmission electron microscopy (3D TEM) combined with force analysis to study the interface.
By confining air and water inside a carbon nanotube just 50 nanometers wide, they were able to directly observe the interface's irregular, twisting shape and deduce the repulsive force holding the thin films together, reaching up to 10 megapascals. The intense electric field from molecular alignment is believed to be the missing piece, as classical theories could not explain the observed forces.
The team also found gold nanoparticles spontaneously forming within 2 nanometers of the interface, demonstrating that chemical reactions occur at these tiny scales. This methodology could be applied to other materials, liquids, and reactions, offering a reference for designing nanoscale systems, including those used in fuel cells and water electrolysis for carbon-neutral energy production.
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