Regresar

Using surface plasmonics to turn on fullerene's dark excitons

Abstract:

Using our recently proposed Bethe-Salpeter G0W0 formulation, we explore the optical absorption spectra of fullerene (C60) near coinage metal surfaces (Cu, Ag, and Au). We pay special attention to how the surface plasmon ωS influences the optical activity of fullerene. We find that the lower-energy fullerene excitons at 3.77 and 4.8 eV only weakly interact with the surface plasmon. However, we find that the surface plasmon strongly interacts with the most intense fullerene π exciton, i.e., the dipolar mode at ℏω+≈6.5 eV, and the quadrupolar mode at ℏω-≈6.8 eV. When fullerene is close to a copper surface (z0≈5.3 Å), the dipolar mode ω+ and "localized" surface plasmons in the molecule/surface interface hybridize to form two coupled modes which both absorb light. As a result, the molecule gains an additional optically active mode. Moreover, in resonance, when ωS≈ω±, the strong interaction with the surface plasmon destroys the ω-quadrupolar character and it becomes an optically active mode. In this case, the molecule gains two additional very intense optically active modes. Further, we find that this resonance condition, ωS≈ω±, is satisfied by silver and gold metal surfaces. © 2014 American Physical Society.