From Local Covalent Bonding to Extended Electric Field Interactions in Proton Hydration

Maria Ekimova, Carlo Kleine, Jan Ludwig, Miguel Ochmann, Thomas E.G. Agrenius, Eve Kozari, Dina Pines, Ehud Pines, Nils Huse, Philippe Wernet, Michael Odelius, Erik T.J. Nibbering

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


Seemingly simple yet surprisingly difficult to probe, excess protons in water constitute complex quantum objects with strong interactions with the extended and dynamically changing hydrogen-bonding network of the liquid. Proton hydration plays pivotal roles in energy transport in hydrogen fuel cells and signal transduction in transmembrane proteins. While geometries and stoichiometry have been widely addressed in both experiment and theory, the electronic structure of these specific hydrated proton complexes has remained elusive. Here we show, layer by layer, how utilizing novel flatjet technology for accurate x-ray spectroscopic measurements and combining infrared spectral analysis and calculations, we find orbital-specific markers that distinguish two main electronic-structure effects: Local orbital interactions determine covalent bonding between the proton and neigbouring water molecules, while orbital-energy shifts measure the strength of the extended electric field of the proton.

Original languageEnglish
Article numbere202211066
JournalAngewandte Chemie - International Edition
Issue number46
StatePublished - 14 Nov 2022


  • Eigen Cation
  • Electronic Structure
  • Hydrated Proton
  • Soft X-Ray Absorption Spectroscopy
  • Zundel Cation

ASJC Scopus subject areas

  • General Chemistry
  • Catalysis


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