Direct evidence of two interatomic relaxation mechanisms in argon dimers ionized by electron impact

• Published in: Nature communications 2016-03, Vol.7 (1), p.11093-11093, Article 11093
• Main Authors: Ren, Xueguang, Jabbour Al Maalouf, Elias, Dorn, Alexander, Denifl, Stephan
• Format: Article
• Language: English
• Subjects: 639/638/440/947; 639/638/440/948; 639/766/36/1120; Humanities and Social Sciences; multidisciplinary; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms11093

In weakly bound systems like liquids and clusters electronically excited states can relax in inter-particle reactions via the interplay of electronic and nuclear dynamics. Here we report on the identification of two prominent examples, interatomic Coulombic decay (ICD) and radiative charge transfer (RCT), which are induced in argon dimers by electron collisions. After initial ionization of one dimer constituent ICD and RCT lead to the ionization of its neighbour either by energy transfer to or by electron transfer from the neighbour, respectively. By full quintuple-coincidence measurements, we unambiguously identify ICD and RCT, and trace the relaxation dynamics as function of the collisional excited state energies. Such interatomic processes multiply the number of electrons and shift their energies down to the critical 1–10 eV range, which can efficiently cause chemical degradation of biomolecules. Therefore, the observed relaxation channels might contribute to cause efficient radiation damage in biological systems. Inter-particle reactions in weakly bound systems are often difficult to pinpoint by detecting exclusively the kinetic energy of the produced ions. Here the authors present a full-coincidence experiment, where inter-particle reaction channels are determined by the measurement of all outgoing particles.