Autoionization Mediated by Electron Transfer

Abstract

Electron-electron coincidence spectra of Ar-Kr clusters after photoionization have been measured. An electron with the kinetic energy range from 0 to approximately 1 eV is found in coincidence with the Ar 3s cluster photoelectron. The low kinetic energy electron can be attributed to an Ar + Kr+ + Kr+ final state which forms after electron transfer mediated decay. This autoionization mechanism results from a concerted transition involving three different atoms in a van der Waals cluster; it was predicted theoretically, but hitherto not observed.

Efficient Pathway to Neutralization of Multiply Charged Ions Produced in Auger Processes

“…In ETMD (see Fig. 1) a neighbor donates an electron to the ion, while the released energy is simultaneously transferred either to the donor or to another neighboring species ionizing an additional electron [18][19][20]. Therefore, the neutralization of ions via ETMD is accompanied by an increase in the charge state of the complete system.…”

Tracing Ultrafast Electron Dynamics by Modern Propagator Approaches

“…ICD processes involve a virtual photon exchange, and therefore occur on a much shorter time scale than ETMD, where a particle must be transferred from one site to a neighboring site. For Ar/Kr clusters, an ETMD process could now be experimentally observed [36] in accord with theoretical predictions [37], whereas for the Ar/Xe system the situation is much less clear-cut, as demonstrated in studies conducted by Faßhauer [38]. Before discussing any recent results for the Ar/Xe system, however, a brief report of the findings for the Ar/Kr trimer might be applicable.…”

Interatomic Coulombic decay in mixed NeKr clusters

“…5 This recently commissioned device has been described in detail by Mucke et al 42 and has been successfully used for photoelectron spectroscopy of Ar clusters 18,19 and of a fast beam of anions (OH − and O − ) produced by an optical laser. 43,44 In short, the experimental setup makes use of an inhomogeneous magnetic field to extract and parallelize the electrons emerging from the ionization processes and a homogeneous magnetic field to guide the electrons to a microchannel plate (MCP) detector. In our set-up, the total length of the drift tube is at 60 cm.…”

“…It is referred to as Interatomic (or Intermolecular) Coulombic Decay (ICD); more recently, a related process, termed Electron Transfer Mediated Decay (ETMD) has also been discovered. 9,10 In order for ICD to take place, a "minimum energy criterion" has to be fulfilled, namely, the binding energy of the inner valence electron, the emission of which starts the process, must exceed the double ionization potential (DIP) of the system. For the final states in question, the relevant limit is the sum of the binding energies of both outer valence electrons taking part in the decay, to which the Coulomb repulsion energy of the two vacancies in the final state needs to be added.…”