A hitherto unrecognized source of low-energy electrons in water

Most of the low-energy electrons emitted from a material when it is subjected to ionization radiation are believed to be directly ionized secondary electrons. Coincidence measurements of the electrons ejected from water clusters suggests many are produced by a quantitatively new mechanism, known as...

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Bibliographic Details
Published in:Nature physics 2010-02, Vol.6 (2), p.143-146
Main Authors: Mucke, Melanie, Braune, Markus, Barth, Silko, Förstel, Marko, Lischke, Toralf, Ulrich, Volker, Arion, Tiberiu, Becker, Uwe, Bradshaw, Alex, Hergenhahn, Uwe
Format: Article
Language:English
Subjects:
Aggregates
Aqueous solutions
Atomic
Biophysics
Classical and Continuum Physics
Complex Systems
Condensed Matter Physics
Decay
Electrons
Energy
Ionization
Ionizing radiation
letter
Mathematical and Computational Physics
Molecular
Neon
Optical and Plasma Physics
Physics
Physics and Astronomy
Theoretical
Ultraviolet radiation
Water
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Summary:Most of the low-energy electrons emitted from a material when it is subjected to ionization radiation are believed to be directly ionized secondary electrons. Coincidence measurements of the electrons ejected from water clusters suggests many are produced by a quantitatively new mechanism, known as intermolecular Coulombic decay. Low-energy electrons are the most abundant product of ionizing radiation in condensed matter. The origin of these electrons is most commonly understood to be secondary electrons 1 ionized from core or valence levels by incident radiation and slowed by multiple inelastic scattering events. Here, we investigate the production of low-energy electrons in amorphous medium-sized water clusters, which simulate water molecules in an aqueous environment. We identify a hitherto unrecognized extra source of low-energy electrons produced by a non-local autoionization process called intermolecular coulombic decay 2 (ICD). The unequivocal signature of this process is observed in coincidence measurements of low-energy electrons and photoelectrons generated from inner-valence states with vacuum-ultraviolet light. As ICD is expected to take place universally in weakly bound aggregates containing light atoms between carbon and neon in the periodic table 2 , 3 , these results could have implications for our understanding of ionization damage in living tissues.
ISSN:1745-2473
1745-2481
DOI:10.1038/nphys1500