Decay pathways and dissociation energies of copper clusters, Cun+ (2⩽n⩽25), Cun2+ (15⩽n⩽25)

The fragmentation pathways and dissociation energies of copper cluster cations, Cun+ and Cun2+, are determined by multiple-collision induced dissociation. For singly charged clusters, an odd–even staggering is observed throughout the investigated size range, 2⩽n⩽25, where the odd-size clusters have a higher dissociation energy than the average value of their even-size neighbors. The odd–even effect decreases with increasing cluster size. In small clusters it manifests itself by dimer evaporation of the odd-size clusters with n=3,5,11 and possibly n=7, while for all other cluster sizes dissociation by neutral monomer evaporation is observed. The clusters of size n=3, 9, 15, and 21 show particularly high dissociation energies and thus indicate electronic shell closures for n=2, 8, 14, and 20 atomic valence electrons. These results are compared with recent density functional theory calculations. The investigations on singly charged clusters are complemented by studies on doubly charged Cun2+, n=15–25. These ...