Fig. 1 | Nature Communications

Fig. 1

From: Coherent exciton-vibrational dynamics and energy transfer in conjugated organics

Fig. 1

Electronic and vibrational coupling during internal conversion. a Schematic representation of dynamics through the non-adiabatic region (colored box) on two potential energy surfaces defined by electronic wavefunctions Ψ1 and Ψ2 with dependence on electronic degrees of freedom R. During internal conversion, the efficiency of the transition of the photoexcited wavepacket from the upper to the lower surface is driven by the derivative non-adiabatic coupling d12. On the upper surface, the wavepacket is pushed towards the crossing by the Pechukas force, P, acting in the direction of the non-adiabatic coupling vector (NAC). b The wavefunction on a finite molecule adopts a standing wave pattern according to the particle (exciton) in a box model exhibiting either “symmetric” (Ψ1) or “antisymmetric” (Ψ2) form. The non-adiabatic transition from Ψ2 to Ψ1 corresponds to an antisymmetric-to-symmetric transition between neighboring wavefunctions. c The two lowest energy excited states in the polyacetelene conjugated polymer exhibit Ag and Bu symmetries. d The resulting vibrational excitation has an asymmetric form where the left and right part of the system experience structural deformations with opposite phase (expansion and compression). e Sloshing of the localized wavefunction between left and right sides of the double well potential is initiated by the asymmetric vibrational excitation which causes periodic modulations in the potential energy surface on the lower state

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