Pressure dependent formation of small Cu and Ag particles during laser ablation

In this paper the possibility of application of laser ablation in inert gas atmosphere for deposition of nanosized particles is examined. Cu and Ag were deposited by laser ablation in 0–10 mbar Ar atmosphere. The samples were characterized by TEM and XPS. It was found that below 1 mbar for Cu and 2 mbar for Ag, island like thin film formation occurs. In Cu above 1 mbar lonely nanoparticles with diameters of 3–4 nm as well as large cluster aggregates were found, instead of the islands. This morphology remained unchanged up to 10 mbar. On the contrary, in Ag at 5 mbar individual particles with sizes of 4–6 nm were observed instead of the aggregates or islands. At 10 mbar the number of the 4–6 nm particles strongly decreased, and particles in the size range of 10 nm became dominant. The observed results may be related to the different decelerating rate of the evaporated Cu and Ag atoms in the Ar atmosphere.