Issue
EPL
Volume 81, Number 6, March 2008
Article Number 64006
Number of page(s) 5
Section Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics, and Fluid Dynamics
DOI http://dx.doi.org/10.1209/0295-5075/81/64006
Published online 28 February 2008
EPL, 81 (2008) 64006
DOI: 10.1209/0295-5075/81/64006

Correlation between geometry and nanobubble distribution on HOPG surface

S. Yang1, 2, E. S. Kooij2, B. Poelsema2, D. Lohse1 and H. J. W. Zandvliet2

1  Physics of Fluids Group, Faculty of Science and Technology, MESA+ Institute for Nanotechnology, University of Twente - 7500 AE Enschede, The Netherlands
2  Solid State Physics Group, Faculty of Science and Technology, MESA+ Institute for Nanotechnology, University of Twente - 7500 AE Enschede, The Netherlands


received 12 September 2007; accepted in final form 30 January 2008; published March 2008
published online 28 February 2008

Abstract
We show that the distribution of nanobubbles is inhomogeneous on the (under-water) surface of highly orientated pyrolytic graphite (HOPG), reflecting the atomic steps: The formation of nanobubbles is strongly enhanced at the upper side of the atomic steps, i.e., the most hydrophobic area on the surface. In contrast, no nanobubbles are formed at the lower side of the steps, i.e., the most hydrophilic area. The width of this nanobubble-free zone is approximately 20 nm. We thus establish a correlation between surface topography and nanobubble formation. In addition, we show that the profile of nanobubbles is sensitive to the applied AFM tip-force, demonstrating the deformability of nanobubbles.

PACS
47.55.db - Drop and bubble formation.
68.08.-p - Liquid-solid interfaces.
68.37.Ps - Atomic force microscopy (AFM).

© EPLA 2008