Fig. 2.

Potential energy surface along a dissociative mode. Plot of the potential energy surfaces along the Fe–C(O) distance. The LS state S₀, and the ¹Q states are shown in black and magenta, respectively. The singlet manifold is shown in orange, the triplet manifold in green and the quintet manifold in blue. The metal-centered (MC) states are shown explicitly, whereas the metal-to-ligand charge transfer (MLCT) states are depicted as a quasi-continuous band. Further, a schematic evolution of the wavepacket dynamics is shown. After absorption to the Q-band, the wavepacket undergoes large-amplitude oscillations in the Fe–CO coordinate on the ¹MLCT state. Then, it cascades down acquiring more ³MLCT and ⁵MLCT character as the spin crossover transitions occur. Finally, the wavepacket disperses, and the Fe–C(O) distance oscillations decrease to a value of 2.2 Å