Figure 2.

The energy level diagram for the charge neutral manifold of tetraphenylporphyrin (TPP) molecule and coupled quantum plasmon modes. The relevant (Q-band) electronic states S₀ and S₁ are shown with their associated vibrational levels. The observed optical gap of TPP is 1.89 eV, with a vibrational state spacing of 0.16 eV¹⁸. Based on comparison with experiment, the source and drain tunnel couplings are set to $\hslash {\mathrm{\Gamma }}^{\mathrm{S}}=\hslash {\mathrm{\Gamma }}^{\mathrm{D}}$ = 16.4 μ eV, while the vibrational damping γ_vib, and radiative decay γ_r, are consistent with a vibrational lifetime of 2 ps and a radiative lifetime of 2 ns¹⁸. We set the plasmonic decay to $\hslash \kappa =10meV$ and plexcitonic coupling g is taken as an adjustable parameter.