School of Chemistry F11, University of Sydney, NSW, 2006, Australia.
Phys. Rev. Lett. 80, 5357-5360 (1998).
Abstract
Atomic force microscopy on hydrophobic microspheres in water
reveals a strong attraction with a range of 20--200 nm,
following an initial steep repulsion
at long range.
The data are consistent with a single
sub-microscopic bubble between the surfaces,
with the attraction due to its attachment and lateral spread,
and the repulsion dependent on film drainage
and the electric double layer.
The results provide direct experimental evidence
of the existence of long-lived sub-micron bubbles,
and of their bridging as the cause of the measured long-range attractions
between macroscopic hydrophobic surfaces.
PACS:
07.79.Lh Atomic force microscopes
61.16.Ch Scanning probe microscopy: scanning tunneling, atomic force,
scanning optical, magnetic force, etc
68.10.Cr Surface energy (surface tension, interface tension,
angle of contact, etc.)
68.15.+e Liquid thin films
68.35.Md Surface energy; thermodynamic properties
82.65.Dp Thermodynamics of surfaces and interfaces
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