Ultrafast Spin Crossover in [FeII(bpy)3]2+: Revealing Two Competing Mechanisms by Extreme Ultraviolet Photoemission Spectroscopy

Alexandre Moguilevski, Martin Wilke, Gilbert Grell, Sergey I. Bokarev, Saadullah G. Aziz, Nicholas Engel, Azhr A. Raheem, Oliver Kühn, Igor Yu Kiyan, Emad F. Aziz

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31 Citations (Scopus)


Photoinduced spin-flip in FeII complexes is an ultrafast phenomenon that has the potential to become an alternative to conventional processing and magnetic storage of information. Following the initial excitation by visible light into the singlet metal-to-ligand charge-transfer state, the electronic transition to the high-spin quintet state may undergo different pathways. Here we apply ultrafast XUV (extreme ultraviolet) photoemission spectroscopy to track the low-to-high spin dynamics in the aqueous iron tris-bipyridine complex, [Fe(bpy)3]2+, by monitoring the transient electron density distribution among excited states with femtosecond time resolution. Aided by first-principles calculations, this approach enables us to reveal unambiguously both the sequential and direct de-excitation pathways from singlet to quintet state, with a branching ratio of 4.5:1.

Original languageEnglish
Pages (from-to)465-469
Number of pages5
Issue number5
Publication statusPublished - 3 Mar 2017


  • ab initio calculations
  • photocatalysis
  • photoelectron spectroscopy
  • spin crossover
  • ultrafast non-adiabatic dynamics

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