  We demonstrate importance of molecular multiple excitons and higher-order
plasmons for both enhancement and quenching of resonance Raman and fluorescence
of single dye molecule located at plasmonic hotspot under strong coupling
regime. The multiple excitons induce complicated spectral changes in plasmon
resonance and higher-order plasmons yield drastic quenching for both resonant
Raman and fluorescence. A coupled oscillator model composed of plasmon and
multiple excitons reproduces the complicated spectral changes. Purcell factors
derived from higher-order plasmons reproduce the drastic quenching with
considering ultra-fast surface enhanced fluorescence.
