Identifying Eigen-like hydrated protons at negatively charged interfaces

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 technique, 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. Centered at ~2540 cm−1, the band is seen to shift to ~1875 cm−1 when forming D3O+ upon isotopic substitution. The results offer the possibility of tracking and understanding from a molecular perspective the behavior of hydrated protons at charged interfaces.

Nature of hydrated proton vibrations revealed by nonlinear spectroscopy of acid water nanodroplets

Using polarization-resolved pump–probe spectroscopy we find that hydrated protons have two different OH-stretch vibrations, which are due to asymmetry of the hydration structure.

Identifying Eigen-Like Hydrated Protons at Negatively Charged Interfaces

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.

Identifying Eigen-Like Hydrated Protons at Negatively Charged Interfaces

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.

Interconversion of hydrated protons at the interface between liquid water and platinum

The free energy barriers for hydrogen transfer at the H2O/Pt(111) interface calculated usingab initiomolecular dynamics and umbrella sampling.