Photoelectron Spectroscopy of Clusters and Adsorbates on Clusters

The electronic and geometric structure of free metal cluster anions is studied by photodetachment. The cluster anions are produced in a PACIS (Pulsed Arc Cluster Ion Source). From mass separated bunches of anions electrons are detached by a UV‐laser pulse. Photoelectron spectra of the detached electrons are measured with a “magnetic bottle” type time of flight spectrometer. First data on Ga   n −clusters are presented and compared to similar measurements on Al   n −clusters. At the high resolution (∽ 30 meV) accessible with this experimental set up comparison of the data with calculations delivers new insights into the geometric structure of the particles. A first application of this technique to molecules adsorbed on metal clusters is presented.