Maximal raman optical activity in hybrid single molecule-plasmonic nanostructures with multiple dipolar resonances

We show that a hybrid system built of a plasmonic nanoparticle cluster and a single molecule can attain maximal Raman optical activity (ROA), converting linearly polarized light into purely circularly polarized light at the Raman-scattered frequency. In contrast to standard molecular ROA, the effect described here does not involve magnetic modes and is attributed to off-resonance excitation of electric-dipole plasmon modes of the nanoparticle cluster. A model based on a combination of harmonic oscillators excited at the frequency of the Raman-scattered light is shown to successfully capture the physics of the effect.