DIFFRACTION EFFECTS IN THE PHOTOIONIZATION OF CLUSTERS

In many atomic or molecular clusters an electron cloud exists which is delocalized over a volume of well defined shape. It is shown that the total and partial photoionization cross sections of those clusters os cillate on a scale of energy typically reached by synchrotron radiatio n. The frequencies of the oscillations are related to geometrical prop erties of the electron cloud, such as its thickness and the diameter o f the cluster. These properties can in principle be extracted from the experimental photo cross section. As specific examples we discuss an alkali-metal cluster (Na-40) and the fullerene C-60. (C) 1997 Publishe d by Elsevier Science B.V.