The observation of unusual resonance channels in the electron attachment to mixed argon-oxygen clusters

An additional electron attachment resonance peak, not observable in pure oxygen cluster anions, has been found at an energy of about 11.5 eV for both the stoichiometric Ar m (O 2) n − and the nonstoichiometric Ar m (O 2) n−1 O − cluster anions (produced by electron attachment to mixed argon-oxygen clusters). Two possible competing mechanisms are proposed to explain the appearance of these resonance peaks, i.e. the multiple-collision electron-scavenging mechanism and the core-excited resonance attachment mechanism. From the peak-width analysis it follows that in Ar m (O 2) 2 − the first mechanism is dominant, while in Ar m (O 2) n−1 O − the second mechanism seems to be the only one occurring.