When a solid material is immersed in a liquid, the liquid immediately next to its surface differs from that of the bulk liquid at the molecular level. This interfacial layer is critical to our understanding of a diverse set of phenomena from biology to materials science. When the solid surface is charged, just like an electrode in a working battery, it can drive further changes in the interfacial liquid. However, elucidating the molecular structure at the solid-liquid interface under these conditions has proven difficult.
Now, for the first time, researchers at the US Department of Energy's (DOE) Lawrence Berkeley National Laboratory (Berkeley Lab) have observed the molecular structure of liquid water at a gold surface under different charging conditions.