Figure 4.

State diagram of the molecule–metal system. Transitions are allowed from the molecular ground state |g⁰⟩ to one or more of the excited states |e⁰⟩ through ⟨g⁰|M_σ|e⁰⟩, where M_σ is the dipole moment of the electronic transition. (a) For the B term, a molecule-to-metal CT transition is allowed through ⟨g⁰|M_σ|F⟩. The states |F⁰⟩ and |e⁰⟩ are connected through the HT vibronic coupling term . For the C term, a metal-to-molecule CT transition is allowed through ⟨F|M_σ|e⁰⟩. (b) States |F⟩ and |g⁰⟩ are connected through the HT vibronic coupling term . Reprinted with permission from ref (26). Copyright 2016 John Wiley & Sons, Ltd.