The photoionization of antimony clusters has been studied in the energy range 20–120 eV, probing the inner-valence 4d-np tranistions as well as the shape resonance 4d-ɛf. When the cluster size is varied the photoionization efficiency presents a quite surprising behavior: For all clusters, except the ${\mathrm{Sb}}_{4\mathit{p}}$ group with p>1, the photoionization pattern is similar to that which is known for the bulk. On the other hand, the shape resonance collapses completely for ${\mathrm{Sb}}_{4\mathit{p}}$. It is further shown that this dramatic change of the resonance intensity is itself dependent on the nucleation conditions, which could indicate the influence of the molecular architecture.

• Received 31 May 1991

DOI:https://doi.org/10.1103/PhysRevLett.67.1222