Observation of intermolecular Coulombic decay in liquid water

TL;DR

This study reports the first experimental observation of intermolecular Coulombic decay in liquid water, highlighting its role in generating low-energy electrons that contribute to radiation damage in aqueous environments.

Contribution

It provides the first direct experimental evidence of ICD in liquid water using advanced coincidence spectroscopy techniques.

Findings

ICD observed in liquid water after inner-valence ionization

Quantitative data on electron velocity distribution from ICD

ICD contributes significantly to low-energy electron production in water

Abstract

We report the first observation of intermolecular Coulombic decay (ICD) in liquid water following inner-valence ionization. By combining a monochromatized table-top high-harmonic source with a liquid micro-jet, we recorded electron-electron coincidence spectra at two photon energies that identify the ICD electrons, together with the photoelectrons originating from the 2a1 inner-valence band of liquid water. Our results confirm the importance of ICD as a source of low-energy electrons in bulk liquid water and provide quantitative results for modeling the velocity distribution of the slow electrons that are thought to dominate radiation damage in aqueous environments.