Surface‐enhanced micro‐CARS mapping of a nanostructured cerium dioxide/aluminum film surface with gold nanoparticle‐bound organic molecules

Abstract

AbstractHighly contrast epi‐surface‐enhanced coherent anti‐Stokes Raman scattering (SECARS) microimages of Au‐nanoparticle‐bound organic reporter molecule distributions at a surface of novel surface‐enhanced Raman scattering (SERS)‐active metamaterial junctions, based on nanoparticles spread over a nanostructured CeO2 faceted dielectric film, deposited on an Al sublayer, were recorded at two‐color picosecond excitation of the surface in the near‐infrared spectral range. For this, a scanning confocal laser‐based micro‐CARS spectrometer was employed. The investigations showed that at Raman resonant laser excitation of the molecules/Au‐NP conjugates immobilized on the surface strong SECARS signals can be generated with laser powers not deteriorating the conjugates. Coupling CARS with the plasmonic metamaterial structures under investigation provided excellent chemical imaging contrast (up to 400) for biochemically relevant 5‐thio(2‐nitrobenzoic acid) and 4‐mercaptophenylboronic acid reporter molecules. Taking into account easy handling and utmost long‐term stability of the investigated metamaterial junction at ambient conditions, it might be considered as a promising perspective for a single‐molecule‐sensitivity surface‐enhanced Raman scattering or SECARS biosensor.