Identifying Eigen-Like Hydrated Protons at Negatively Charged Interfaces

22 August 2019, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


Despite the importance of the hydrogen ion in a wide range of biological, chemical, and physical processes, its molecular structure in solution remains lively debated. Progress has been primarily hampered by the extreme diffuse nature of the vibrational signatures of hydrated protons in bulk solution. Using the inherently surface-specific vibrational sum frequency spectroscopy, we show that at selected negatively charged interfaces, a resolved spectral feature directly linked to the H3O+ core in an Eigen-like species can be readily identified in a biologically compatible pH range. The results offer a new molecular perspective for tracking and understanding the behaviour of hydrated protons at interfaces.


Vibrational Sum Frequency Spectroscopy
hydrated proton
Proton continuum
charged interfaces
Fatty acid Langmuir monolayer
Fatty sulphate
Molecular structure

Supplementary materials

Supplementary Information Eigen like protons at the surface


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