Synthesis by pulsed laser ablation in Ar and SERS activity of silver thin films with controlled nanostructure

Thin silve films were deposited by pulsed laser ablation in a controlled Ar atmosphere and their SERS activity was investigated. The samples were grown at Ar pressures between 10 and 70 Pa and at different laser pulse number. Other deposition parameters such as laser fluence, target to substrate distance and substrate temperature were kept fixed at 2.0 J/sm², 35 mm and 297 K. Film morphologies were investigated by scanning and transmission of electron microscopies. Cluster growth is favored by plume confinement induced by background gas. After landing on the substrate clusters it starts to aggregate giving rise to larger structures as long as the deposition goes on. The dependence of the film SERS activity on their surface morphology is discussed