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Localized surface plasmon resonance (LSPR) characteristics of gold nanoparticles films grown at different substrate temperatures and mass thicknesses with and without alumina capping were studied. At different film mass thicknesses, the LSPR response was observed mainly in the films grown at high substrate temperatures. About 300 °C substrate temperature was found to be optimum for producing narrow and strong LSPR band in both uncapped and alumina capped gold nanoparticles films. The LSPR wavelength could be tuned in the range of 600–750 nm by changing either number of ablation pulses or decreasing target to substrate distance (TSD) and alumina layer capping. Though the alumina capping re-sputtered the gold films still these films exhibited stronger LSPR response compared to the uncapped films. Atomic force microscopic analysis revealed formation of densely packed nanoparticles films exhibiting strong LSPR response which is consistent with the package density of the nanoparticles predicted by the theoretical calculations. The average size of nanoparticles increased with substrate temperature, number of ablation pulses and decreasing the TSD. For the same mass thickness of gold films grown at different substrate temperatures the surface enhanced Raman scattering (SERS) intensity of Rhodamine6G dye was found to be significantly different which had direct correlation with the LSPR strength of the films at the excitation wavelength.

The optical responses of gold nanoparticle films and thin continuous films grown by pulsed laser deposition (PLD) in a wide range of process parameters were studied. The growth conditions for obtaining strong surface plasmon resonances (SPR) were optimized. Laser fluence and substrate temperature were found to play key roles in the SPR characteristics of the grown films. The SPR wavelength was tuned in the range of 580–720 nm by varying number of pulses and target-to-substrate distance during the PLD. Atomic force microscopic analysis revealed that the size of metal nanoparticles systematically increased with increasing number of pulses and decreasing target-to-substrate distance. Morphology of the films, which exhibited strong SPR showed densely packed spheroid nanoparticles of gold. Theoretical calculations of SPR wavelengths for the presently studied densely packed gold nanoparticle films were carried out using modified Yamaguchi model which incorporate particle–substrate and particle–particle interactions. From these calculations it was found that the observed SPR responses and their tuning arise from the combination of high volume filling fraction and aspect ratios of the gold nanoparticles.