Efficient Fluorescence Quenching by Distant Production of a Free Electron.

Energy and charge transfer processes play an important role in many fundamental reactions in chemistry, biochemistry, and even technology. If an entity that is part of a larger system is photoexcited, its energy will dissipate, for example, by rearrangement of electron density in a large molecule or by photon emission (fluorescence). Here, we report the experimental observation of free electrons from a heterogeneous van der Waals cluster, in which some sites act as electron emitters receiving their energy efficiently from other "antenna" sites that are resonantly excited in the UV range. By complementing electron spectroscopy with fluorescence detection, we can directly observe that electron emission via this mechanism completely quenches fluorescence once the channel opens. We suggest this mechanism to be important for both quenching of fluorescence as well as resonantly enhancing free electron production in a variety of systems.