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Article Dans Une Revue Communications Physics Année : 2022

Dynamical limits for the molecular switching in a photoexcited material revealed by X-ray diffraction

Alix Volte
  • Fonction : Auteur
  • PersonId : 177244
  • IdHAL : alix-volte
Roman Bertoni
Marco Cammarata
Elzbieta Trzop
Hervé Cailleau
Eric Collet
Jacek Kubicki

Résumé

Time-resolved studies with temporal resolution that separate molecular level dynamics from macroscopic changes, allow clear distinction between the time scales of the different degrees of freedom involved. Cooperative molecular switching in the solid state is exemplified by spin crossover phenomenon in crystals of transition metal complexes. Here we show the existence of a delay between the crystalline volume increase, and the cooperative macroscopic switching of molecular state. Using 100 ps X-ray diffraction, we track the molecular spin state and the structure of the lattice during the photoinduced low spin to high spin transition in microcrystals of [Fe III (3-MeO-SalEen) 2 ]PF 6 . Model simulations explain the phenomenon with thermally activated kinetics governed by local energy barriers separating the molecular states. Such behaviour is different from that encountered in materials with no local energy barriers, where phase transformation can occur simultaneously with propagation of strain. Broadly, this motivates an optimised material design, scalable with size and intrinsic energetics. Ultrafast methods have the ability to transiently decouple transitions between subsystems that evolve simultaneously at thermal equilibrium. Here, time-resolved X-ray diffraction reveals a time delay between volumetric and spin-state switching in a spin-crossover compound.
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Dates et versions

hal-03723851 , version 1 (15-07-2022)

Identifiants

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Alix Volte, Celine Mariette, Roman Bertoni, Marco Cammarata, Xu Dong, et al.. Dynamical limits for the molecular switching in a photoexcited material revealed by X-ray diffraction. Communications Physics, 2022, 5 (1), pp.168. ⟨10.1038/s42005-022-00940-0⟩. ⟨hal-03723851⟩
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