Neutral clusters experimental difficulties

When facing a full collision process, the existence of such a partial electron transfer state is elusive and usually difficult to evidence experimentally. A major difficulty comes from its transient character. A convenient approach to stabilize the electron transfer between two encounters is to consider a complex formed with both of them. This was the case with the Au (H20) complex mentioned above. This is also the case with the neutral van der Waals complexes considered hereafter. In this case, the characterization of the charge-transfer state requires a careful experimental investigation. We review here how spectroscopy of these clusters can characterize partial electron transfers. 

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