Size and charge-state dependence of detachment energies of polyanionic silver clusters

Abstract

The electronic properties of silver clusters (N up to 800) charged by attachment of up to z = 7 excess electrons are investigated. As an essential preparation step, the technique of in-trap electron attachment to size-selected monoanions within a linear Paul trap is applied. By taking advantage of tunable laser pulses, the photoelectron spectra allow us to evaluate details of the electronic structure of polyanionic metal clusters, giving a multidimensional dataset. The subsequent analysis based on the liquid drop model provides information about the atomic structure and the bulk work function at a hitherto unknown quality.

A versatile setup for studying size and charge-state selected polyanionic nanoparticles

“…By using tunable laser pulses, wavelength-dependent photoelectron spectroscopy is realized, which enables the study for, e.g. Coulomb barriers, 48 detachment energies, 42 sequential multiphoton detachment, as well as the optical response. In contrast to Penning traps, the storage capabilities of rf ion traps give access to much larger clusters.…”

“…This possibly indicates a finite lifetime on the order of the experimental cycle duration due to the metastable nature of Ag 7− 800 . 42 Note that due to multiple collisions and the storage conditions, this experimental lifetime only provides a lower limit with respect to the tunneling lifetime of undisturbed clusters of low internal excitation energies.…”

“…800 . 42 The high binding energy wing provides information of the Coulomb barrier. 48 The spectra have been normalized to their maximum.…”

“…To obtain more specific values, detachment energies have to be determined in single-photon experiments on each z separately to avoid interferences with other charge states. 42 Further, between the successive photon absorption events fragmentation has to be considered as it may compete to detachment. 51 Despite the rough approximation in determining the charging energies, the good agreement of the charging energy with the values obtained in 42 suggests that each absorption of a photon triggers the emission of only a single electron.…”

“…42 Further, between the successive photon absorption events fragmentation has to be considered as it may compete to detachment. 51 Despite the rough approximation in determining the charging energies, the good agreement of the charging energy with the values obtained in 42 suggests that each absorption of a photon triggers the emission of only a single electron. 300 obtained at photon energies of E ph = 3.65 eV (black), 3.76 eV (blue) and 3.87 eV (red).…”