Decay processes and radiative cooling of small anionic copper clusters

Abstract

The decay of copper clusters ${\mathrm{Cu}}_{n}^{\ensuremath{-}}$ with size $n=4\ensuremath{-}7$, produced in a metal ion sputter source, was studied in an electrostatic ion-beam trap. The neutral products after electron emission and fragmentation were monitored for ion storage times of up to a second. The observations indicated the presence of radiative cooling. The energy distributions of the remaining clusters were probed by laser irradiation up to several further seconds of storage time. This defined excitation lead to photoinduced decay signals which, again, showed signs of radiative cooling for ${\mathrm{Cu}}_{6,7}^{\ensuremath{-}}$, not, however, for ${\mathrm{Cu}}_{4,5}^{\ensuremath{-}}$.