title: Interatomic Coulombic decay following photoionization of the helium dimer: observation of vibrational structure.
abstract: Using synchrotron radiation we simultaneously ionize and excite one helium atom of a helium dimer (He2) in a shakeup process. The populated states of the dimer ion [i.e., He(*+)(n = 2, 3) - He] are found to deexcite via interatomic Coulombic decay. This leads to the emission of a second electron from the neutral site and a subsequent Coulomb explosion. In this Letter we present a measurement of the momenta of fragments that are created during this reaction. The electron energy distribution and the kinetic energy release of the two He+ ions show pronounced oscillations which we attribute to the structure of the vibrational wave function of the dimer ion.
authors.affiliation: Institut für Kernphysik, J. W. Goethe Universität, Max-von-Laue-Strasse 1, 60438 Frankfurt, Germany.
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authors.lastname: Havermeier
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authors.lastname: Grisenti
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authors.lastname: Dörner