Direct measurement of sub-debye-length attraction between oppositely charged surfaces

Nir Kampf, Dan Ben-Yaakov, David Andelman, S. A. Safran, Jacob Klein

Research output: Contribution to journalArticlepeer-review

Abstract

Using a surface force balance with fast video analysis, we have measured directly the attractive forces between oppositely charged solid surfaces (charge densities σ+, σ-) across water over the entire range of interaction, in particular, at surface separations D below the Debye screening length λS. At very low salt concentration we find a long-ranged attraction between the surfaces (onset ca. 100 nm), whose variation at D<λS agrees well with predictions based on solving the Poisson-Boltzmann theory, when due account is taken of the independently- determined surface charge asymmetry (σ+≠ σ-).

Original languageEnglish
Article number118304
JournalPhysical Review Letters
Volume103
Issue number11
DOIs
StatePublished - 11 Sep 2009

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