In this paper, preparation of nanostructured copper thin films using the pulsed laser deposition technique has been described. Thin films have been prepared at high vacuum, which assures impact of highly energetic ablated species on the film surface. Role of deposition time variations on changing the films nanostructure has been studied and it is shown that by increasing the deposition time, it will evolve from isolated nanoparticles into nanoclusters and eventually a percolated structure composed of aggregated nanoparticles. Furthermore, by increasing the deposition time and consequently the volume fraction of copper nanoparticles, a blue-shift in plasmon absorption peak of our nanostructured copper thin films has occurred and the plasmon linewidth has narrowed simultaneously, which is not in accord with the previous reports. Source of this intriguing behavior has been ascribed to the energetic nature of impacting particles on the film surface at high vacuum conditions and the subsurface growth mode which can facilitate the formation of metastable phases.

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