Molecular Layer of Gaslike Domains at a Hydrophobic–Water Interface Observed by Frequency-Modulation Atomic Force Microscopy

It was numerically predicted that dissolved gas particles could enrich and adsorb at hydrophobic–liquid interfaces. Here we observe nucleation and growth of bright patches of ∼0.45 nm high on the graphite surface in pure water with frequency-modulation atomic force microscopy when the dissolved gas concentration is below the saturation level. The bright patches, suspected to be caused by adsorption of nitrogen molecules at the graphite–water interface, are composed of domains of a rowlike structure with the row separation of 4.2 ± 0.3 nm. The observation of this ordered adlayer might underline the gas segregation at various water interfaces.