Photoelectron spectroscopy on Pt atoms and clusters deposited on C(0001)

An experimental photoelectron spectroscopy study is presented highlighting several aspects of importance for the study of deposited metal clusters and particles with photoemission. It is shown that the Fermi level is the correct energy reference for the core level binding energies. The choice of different deposition conditions, well within the range of soft landing, has a strong impact on the outcome of the spectroscopic experiments. Single adatoms as well as clusters deposited with some excess energy display relatively narrow core level spectra at much lower binding energies than previously reported, even when atomic mass selection is not performed. In contrast, single sized Pt19 clusters, deposited onto a thin Ar film before being exposed to the graphite surface show spectral broadening and shifts to higher binding energies. We discuss our results in terms of the cluster substrate interaction and the influence of deposition conditions on the metal adsorbate structure.