Design and capabilities of an experimental setup based on magnetron sputtering for formation and deposition of size-selected metal clusters on ultra-clean surfaces Rev. Sci. Instrum. 83, 073304 (2012); 10.1063/1.4732821 The effect of graphite surface condition on the composition of Al 2 O 3 by atomic layer deposition Appl. Phys. Lett. 97, 082901 (2010); 10.1063/1.3479908 Metastable ordered arrays of size-selected Ag clusters on graphite Appl. Phys. Lett. 82, 2595 (2003); 10.1063/1.1568165 Characterization of size-selected metal clusters implanted below the surface of graphiteThe effect of 4 keV Ar þ ions on size-selected (MoO 3 ) n and (WO 3 ) n clusters, where n ¼ 30 6 1, deposited on highly ordered pyrolytic graphite was studied by x-ray photoelectron spectroscopy and atomic force microscopy. During deposition, both metal oxide clusters collected preferentially at step edges at low coverages, with larger cluster aggregates nucleating on the terraces at higher coverages. Under the influence of 4 keV Ar þ ion bombardment, both clusters initially experienced oxygen loss and corresponding reduction of the transition metal before the remaining species were sputtered from the surface. However, MoO 3 was only partially reduced to MoO 2 , while WO 3 was fully reduced to metallic tungsten. As a consequence of these variations in ion induced chemistry, changes in the surface morphology of MoO 3 and WO 3 following prolonged Ar þ exposure differed significantly. For (MoO 3 ) 3061 , the size of the clusters decreased, due to removal of MoO 2 fragments. In contrast, for (WO 3 ) 3061 , the formation of smaller sized clusters was also accompanied by the appearance of clusters that were much larger in size than the original "as deposited" clusters. The creation of these larger structures is ascribed to the mobility and coalescence of metallic tungsten species produced during the sputtering process. The contrast in the behavior of the molybdenum and tungsten oxide clusters illustrates the interplay that can exist between ion induced changes in speciation and morphology of deposited clusters.