Surface plasmon resonance tuning in gold film on silver nanospheres through optical absorption

Abstract

The surface plasmon resonance wavelength in a gold film above silver nanospheres on a silica substrate was measured using transmission absorption spectroscopy. The structure, surface morphology, and optical properties of the gold/silver nanosphere thin films were investigated using X-ray diffraction (XRD), atomic force microscopy (AFM), UV-VIS-NIR double beam spectrometry, and Raman spectroscopy, respectively. The silver nanospheres were fabricated by simple thermal annealing. A gold film with thickness ranging from 2 to 50 nm on top of the silver nanospheres exhibits a blue-shift in the resonance wavelength from 590 to 510 nm. Surface-enhanced Raman scattering (SERS) is also reported in this paper. Additionally, finite-difference time-domain (FDTD) simulations were used to describe surface plasmon resonance in the samples, and the numerical results were consistent with experimental results.

Keywords

• Surface plasmon resonance (SPR)
• Blue shift
• Thermal annealing
• Silver nanospheres
• Surface-enhanced Raman scattering (SERS)