Determining the radial distribution function of water using electron scattering: A key to solution phase chemistry

High energy electron scattering of liquid water (H₂O) at near-ambient temperature and pressure was performed in a transmission electron microscope (TEM) to determine the radial distribution of water, which provides information on intra- and intermolecular spatial correlations. A recently developed environmental liquid cell enables formation of a stable water layer, the thickness of which is readily controlled by pressure and flow rate adjustments of a humid air stream passing between two silicon nitride (Si₃N₄) membranes. The analysis of the scattering data is adapted from the x-ray methodology to account for multiple scattering in the H₂O:Si₃N₄ sandwich layer. For the H₂O layer, we obtain oxygen-oxygen (O-O) and oxygen-hydrogen (O-H) peaks at 2.84 Å and 1.83 Å, respectively, in good agreement with values in the literature. This demonstrates the potential of our approach toward future studies of water-based physics and chemistry in TEMs or electron probes of structural dynamics.