Photoemission from tin and lead cluster anions

Abstract

Photoelectrons from mass-identified jet-cooled tin and lead cluster anions (Sn n , Pb n ) are detached by ultraviolet laser light (hngr=3.68 eV). The photoelectron energy spectra give the detachment energies of ground state cluster anions (electron affinities) as well as excitation energies of neutral clusters in the geometry of the anions. The energy spectra for Sn n are dominated by flat thresholds with ann-dependence similar to that of other group IV clusters. In contrast, for Pb n we find pronounced narrow lines close to threshold, generally followed by a 0.3 1.4 eV gap which indicates closed-shell behaviour of Pb n for nearly alln.