Slow spontaneous transformation of the morphology of ultrathin gold films characterized by localized surface plasmon resonance spectroscopy

It has been recognized that ultrathin gold films deposited on unmodified glass substrates are unstable, but there is a lack of systematic studies of their morphology evolution at room temperature. This paper shows that ultrathin gold films sputtered on bare glass substrates could spontaneously transform into nanoporous, nanowire and nanoparticle structures, without any treatment such as heating and UV irradiation. These nanostructures lead to the well-defined localized surface plasmon resonance (LSPR) band. Deposition of a dielectric thin film on the gold nanostructure could prevent structural change. Investigations indicate that the LSPR absorption spectrum of the nanostructured gold film is highly dependent on the polarization state of the light probe and is sensitive to both the refractive index of the surrounding liquid and thickness of the coating layer.