Adsorption Dynamics of CO on Silica-Supported Cu Clusters: A Molecular Beam Scattering Study

The adsorption kinetics and dynamics of CO on silica-supported Cu clusters were studied with thermal desorption spectroscopy and molecular beam scattering. In addition, the electronic properties of the Cu clusters and sample cleanliness were characterized with X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). Physical vapor deposition was used to deposit the clusters; according to XPS, the Cu clusters remain metallic. The CO impact energy, surface temperature, and Cu coverage dependence of the adsorption dynamics can be discussed in the framework of the capture zone model. The XPS/AES and thermal desorption spectroscopy (TDS) data are consistent with a standard growth mode of Cu on silica: a nucleation phase is followed by a cluster growth phase until thick and rather smooth Cu films are formed.