Anomalously low dielectric constant of confined water

Research output: Contribution to journalArticle

  • External authors:
  • A. Esfandiar
  • R. Fabregas
  • Sheng Hu
  • T Taniguchi
  • K Watanabe
  • G Gomila
  • Konstantin Novoselov
  • Andre Geim


The dielectric constant ε of interfacial water has been predicted to be smaller than that of bulk water (ε ≈ 80) because the rotational freedom of water dipoles is expected to decrease near surfaces, yet experimental evidence is lacking. We report local capacitance measurements for water confined between two atomically flat walls separated by various distances down to 1 nanometer. Our experiments reveal the presence of an interfacial layer with vanishingly small polarization such that its out-of-plane ε is only ~2. The electrically dead layer is found to be two to three molecules thick. These results provide much-needed feedback for theories describing water-mediated surface interactions and the behavior of interfacial water, and show a way to investigate the dielectric properties of other fluids and solids under extreme confinement.

Bibliographical metadata

Original languageEnglish
Pages (from-to)1339-1342
Number of pages4
Issue number6395
Early online date22 Jun 2018
Publication statusPublished - 22 Jun 2018

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