Transient Exciplex Formation Electron Transfer Mechanism

Figure 17

Experimental apparent activation free energy (blue □) and activation enthalpy (red ○) for quenching of aromatic compounds by various quenchers [66–71]. Free energies of transient exciplex formation (magenta ▲) are calculated according to (10) (for 𝜏^′₀=1 ns); the entropy of transient exciplex formation (green ♦) 𝑇Δ𝑆_Ex^∗=Δ𝐻_Ex^∗−Δ𝐺_Ex^∗ (assuming Δ𝐻_Ex^∗≈Δ𝐻^‡_App). Simulated curves are: (1)Δ𝐺^‡ for Marcus mechanism ((2), 𝜆=0.6 eV) and (2)Δ𝐺_Ex^∗ for transient exciplex mechanism ((15), 𝑎=0.13, 𝑏=0.07, 𝑐=0.14 eV); (3) Δ𝐻^‡_App=0.12−Δ𝐺_ET^∗/2−((Δ𝐺_ET^∗/2)²+0.14²)^1/2.