Figure 16.

Strong plasmon coupling in Al nanoparticles (NPs) and excitations in benzene molecules. The calculated photoabsorption spectra of NP–molecule systems composed of (a) Al₂₀₁, (b) Al₅₈₆, and (c) Al1₂₈₉ NPs coupled with N benzene molecules at 3 Å separation (solid lines) clearly show separated lower and upper polaritons, the splitting of which increases with increasing N. Spectra of the bare Al particles and benzene molecule are shown for reference (dotted lines). (d) Coupling strengths of the NP–molecule systems. Coupling strengths g for different numbers N of molecules placed 3 Å above the NP. The symbols denote the fitted g values from the data in Figure 2 of ref (183). The dotted lines mark the ideal theoretical coupling strengths , where μ₁ and E_vac are the transition dipole moment and amplitude of vacuum fluctuation, respectively. The dashed lines mark the ideal dependence multiplied by the efficiency factors between the exciton and cavity η for η₂₀₁ = 0.47, η₅₈₆ = 0.61, and η₁₂₈₉ = 0.78 (see Figure 4a and its in-text description for details of ref (183)). Reproduced with permission from ref (183). Copyright 2019 Nature Research.