Stability and Electron Affinities of Negatively Charged Aluminium Clusters: A Computational Study

A computational study on the stability of neutral, singly and doubly negatively charged aluminium clusters Aln z, with n = {13, 18, 23, 39, 55}, and z = {0, -1, -2} is presented.Estimates of electron affinities (EA) were computed with(i) all-electron quantum-mechanical calculations with fullgeometry optimization on Aln z, with n = {13, 18, 23, 39,55}, and z = {0, -1, -2}, using the Perdew-Burke-Ernzerhof(PBE) gradient-corrected functional within Density FunctionalTheory (DFT) and (ii) Charged Conducting-Sphere Model with and without Coulomb barrier and tunnelling corrections. If a positive value for the second electron affinity of the cluster is considered to be the sole criterion for the production and experimental observation of dianionic aluminium clusters, then the predicted minimum cluster size (i.e. the number of atoms) is n ∼ 23 and n ∼ 32 from the all-electron computations and the charged conducting-sphere model, respectively.

Long-term monitoring of the internal energy distribution of isolated cluster systems

A method is presented to monitor the internal energy distribution of cluster anions via delayed electron detachment by pulsed photoexcitation and demonstrated on Co$_4{}^-$ in an electrostatic ion beam trap. In cryogenic operation, we calibrate the detachment delay to internal energy. By laser frequency scans, at room temperature, we reconstruct the time-dependent internal energy distribution of the clusters. The mean energies of ensembles from a cold and a hot ion source both approach thermal equilibrium. Our data yield a radiative emission law and the absorptivity of the cluster for thermal radiation.Comment: Manuscript LaTeX with 6 pages, 4 figures, plus LaTeX supplement with 9 pages, 4 figures and 2 tables. This article has been accepted by Physical Review Letter

Polyanionic metal clusters: How to make 'em and to break 'em

Synopsis Polyanionic metal clusters are produced by electron attachment in both Paul and Penning traps. After size and charge-state selection, the cluster properties are further investigated by various methods including photo-dissociation. Depending on the particular cluster species various decay modes are observed