Item

Abstract

As opposed to purely molecular systems where electron dynamics proceed only
through intramolecular processes, weakly bound complexes such as He droplets
offer an environment where local excitations can interact with neighbouring
embedded molecules leading to new intermolecular relaxation mechanisms. Here,
we report on a new decay mechanism leading to the double ionization of alkali
dimers attached to He droplets by intermolecular energy transfer. From the
electron spectra, the process is similar to the well-known shake-off mechanism
observed in double Auger decay and single-photon double ionization, however, in
this case, the process is dominant, occurring with efficiencies equal to, or
greater than, single ionization by energy transfer. Although an alkali dimer
attached to a He droplet is a model case, the decay mechanism is relevant for
any system where the excitation energy of one constituent exceeds the double
ionization potential of another neighbouring molecule. The process is, in
particular, relevant for biological systems, where radicals and slow electrons
are known to cause radiation damage