Hydrated Electron

When high-energy radiation — from X-rays, nuclear reactions, or even ultraviolet light — strikes liquid water, it can knock electrons free from individual molecules. These free electrons don't attach to a single water molecule (because the water anion is not stable); instead, they burrow into a tiny pocket in the liquid, an electron without a nucleus, stabilized by the hydrogen bonds of the surrounding water molecules. This curious species, called the hydrated electron, is one of the strongest reducing agents known in chemistry and plays a central role in radiation-induced DNA damage and corrosion in nuclear reactors. Despite decades of study, fundamental questions about its structure and reactivity are still unresolved.

We are using ab  initio molecular dynamics simulations to explore both what the hydrated electron looks like at the atomic scale and how it reacts with molecules dissolved in water. One longstanding puzzle is that the hydrated electron's reactions don't follow Marcus theory — the standard framework that chemists use to predict electron-transfer rates — and we are working to understand why. We have also studied how the electron changes the volume of the water solution (its partial molar volume), which connects to experimental measurements and reveals details about the structure of the solvating water molecules. More recently, we have investigated reactions of the hydrated electron with molecules like carbon dioxide and acetone, uncovering reaction pathways and the unusual temperature-independence of some of these rates.