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RESEARCH PRODUCT

Multicollision-induced dissociation of multiply charged gold clusters, Aun2+, n = 7–35, and Aun3+, n = 19–35

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Abstract Multicollision-induced dissociation (MCID) has been applied to gold clusters, Au n 2+ (n = 7–35) and Au n 3+ (n = 19–35) stored in a Penning trap. By application of ion cyclotron resonance excitation and pulses of argon collision gas, fragmentation yields have been measured as a function of the clusters’ kinetic energy. The corresponding dissociation energies have been determined by use of the impulsive collision theory and the quantum Rice–Ramsperger–Kassel (RRK) model for the energy transfer to internal cluster modes and for delayed dissociation, respectively. As compared to earlier measurements of singly charged gold clusters the variation of the stability as a function of cluster size is reduced. The doubly charged clusters show an odd–even effect that is reversed with respect to that of singly charged gold clusters. This is similar to findings by electron impact ionization/dissociation and in line with the expectations for simple metal clusters, where the structure and stability is governed by the number of atomic valence electrons. However, no cluster sizes of particular stability (magic numbers) are observed. In general, the dissociation energy of small clusters is smaller than that of the larger ones because of the influence of the Coulomb force. In contrast to the singly charged gold clusters the odd–even effect of Au n 2+ disappears at small cluster sizes n