Wide-Band Spectral Control of Au Nanoparticle Plasmon Resonances on a Thermally and Chemically Robust Sensing Platform

Gold nanoparticles on Al 2 O 3 -coated gold films are presented as a chemically and thermally robust platform for molecular sensing. Single particle spectroscopy as a function of Al 2 O 3 coating thickness shows reproducible gold nanoparticle scattering spectra in the range from 690 to 610 nm as the Al 2 O 3 thickness increases from 0 to 3.4 nm. Numerical simulation of these structures indicates that surface-enhanced Raman spectroscopy enhancement factors in excess of 10 6 can be achieved. The stability of the Al 2 O 3 -coated structures under high-power laser irradiation was tested, revealing stable scattering spectra upon irradiation with 100 W/mm 2 at the particle resonance wavelength. The presented structure solves challenges with thermal stability, wavelength tuning range, and Raman background signal associated with previously attempted approaches.