Preferred sizes and ordering in surface nanobubble populations.

Area of Science:

• Surface science
• Nanotechnology
• Statistical physics

Background:

• Surface nanobubbles are critical in various physical and chemical processes.
• Understanding their formation and arrangement is key to controlling interfacial phenomena.

Purpose of the Study:

• To statistically analyze the size and spatial distribution of two distinct nanobubble populations.
• To investigate the influence of formation methods on nanobubble arrangement and identify potential structuring effects.

Main Methods:

• Statistical analysis of nanobubble size (R) and radial distribution functions.
• Comparison with Monte Carlo simulations of hard disk packings.

Main Results:

• Case A (droplet deposition): Generalized gamma distribution for bubble size with a preferred radius (R*=20 nm) and preferred spacing (~5.5R*).
• Case B (ethanol-water exchange): Bimodal size distribution with two preferred radii and less significant local ordering.
• Simulations of random packings did not replicate the observed structuring effects.

Conclusions:

• Nanobubble formation methods significantly influence their size distribution and spatial organization.
• Evidence suggests a structuring effect during nanobubble formation, not solely driven by random packing.