Figure 5.
Proposed scheme for radiationless decay of carotenoids after optical preparation of the S2 state. The states that apply to planar structures are indicated by symmetry labels. Key points along the path back to the initial planar ground-state conformation are labelled with ethylenic structures, depicting the Sx, X and S* dark states as twisted structures near the S2 transition state and the S2 twisted minimum and pyramidal structures near the S1 state minimum, respectively. (Reproduced with permission from [102].)