Observation of interatomic Coulombic decay and electron-transfer-mediated decay in high-energy electron-impact ionization of Ar2

We measured the kinetic energy distributions of the fragment ions of doubly and quadruply ionized argon dimers using 3000 eV electron impact. For the dissociation of (Ar2)(2+), the peak that indicates radiative charge transfer is observed, where the outer-shell ionization (dominant in highly charged ion collision) and the inner-shell ionization (preferential in x-ray experiments) have approximately equal contributions. For the dissociation of (Ar2)(4+), the interatomicCoulombic decay and electron-transfer-mediated decay are first observed in the electron-impact process.