title: Ultrafast Spin Crossover in [FeII(bpy)3]2+: Revealing Two Competing Mechanisms by Extreme Ultraviolet Photoemission Spectroscopy.
abstract: Photoinduced spin-flip in FeIIcomplexes 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.
authors.affiliation: Joint Laboratory for Ultrafast Dynamics in Solutions and at Interfaces (JULiq), Institute of Methods for Material Development, Helmholtz-Zentrum Berlin, Albert-Einstein-Str. 15, 12489, Berlin, Germany.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Moguilevski
authors.affiliation: Joint Laboratory for Ultrafast Dynamics in Solutions and at Interfaces (JULiq), Institute of Methods for Material Development, Helmholtz-Zentrum Berlin, Albert-Einstein-Str. 15, 12489, Berlin, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Wilke
authors.affiliation: Institute of Physics, University of Rostock, Albert-Einstein-Str. 23-24, 18059, Rostock, Germany.
authors.forename: Gilbert
authors.initials: G
authors.lastname: Grell
authors.affiliation: Institute of Physics, University of Rostock, Albert-Einstein-Str. 23-24, 18059, Rostock, Germany.
authors.forename: Sergey I
authors.initials: SI
authors.lastname: Bokarev
authors.affiliation: Chemistry Department, Faculty of Science, King Abdulaziz University, 21589, Jeddah, Saudi Arabia.
authors.forename: Saadullah G
authors.initials: SG
authors.lastname: Aziz
authors.affiliation: Joint Laboratory for Ultrafast Dynamics in Solutions and at Interfaces (JULiq), Institute of Methods for Material Development, Helmholtz-Zentrum Berlin, Albert-Einstein-Str. 15, 12489, Berlin, Germany.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Engel
authors.affiliation: Joint Laboratory for Ultrafast Dynamics in Solutions and at Interfaces (JULiq), Institute of Methods for Material Development, Helmholtz-Zentrum Berlin, Albert-Einstein-Str. 15, 12489, Berlin, Germany.
authors.forename: Azhr A
authors.initials: AA
authors.lastname: Raheem
authors.affiliation: Institute of Physics, University of Rostock, Albert-Einstein-Str. 23-24, 18059, Rostock, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Kühn
authors.affiliation: Joint Laboratory for Ultrafast Dynamics in Solutions and at Interfaces (JULiq), Institute of Methods for Material Development, Helmholtz-Zentrum Berlin, Albert-Einstein-Str. 15, 12489, Berlin, Germany.
authors.forename: Igor Yu
authors.initials: IY
authors.lastname: Kiyan
authors.affiliation: Joint Laboratory for Ultrafast Dynamics in Solutions and at Interfaces (JULiq), Institute of Methods for Material Development, Helmholtz-Zentrum Berlin, Albert-Einstein-Str. 15, 12489, Berlin, Germany.|Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany.|School of Chemistry, Monash University, Clayton, 3800, VIC, Australia.
authors.forename: Emad F
authors.initials: EF
authors.lastname: Aziz
keywords: ab initio calculations; photocatalysis; photoelectron spectroscopy; spin crossover; ultrafast non-adiabatic dynamics