Tracking the Complex Dynamics of Electron-Transfer-Mediated Decay in Real Space and Time

When an electronically excited atom or molecule is embedded in a chemical environment as, e.g., in a liquid or a loosely bound cluster, it can de-excite through mechanisms where neighboring atoms or molecules are actively participating in the decay: either by donating or accepting energy or electrons. For such nonlocal decay channels, nuclear dynamics play a crucial role as they have a direct impact on the decay efficiency itself. Here, we present a detailed study of the electron-transfer-mediated decay in a loosely bound triatomic prototype system, combining experimental results from a 5-fold coincidence measurement and theoretical modeling of the decay process. Depending on the decay time, we find that certain classes of molecular geometries are favored for this type of decay. Our findings provide an intuitive picture of how electron-transfer-mediated decay proceeds. In particular, our results confirm a roaming-like behavior of the atoms of the trimer prior to its decay. Our combined theoretical and experimental approach enables a comprehensive tracing of the real-space properties of the decaying system in the time domain.