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Photooxidation and photoaquation of iron hexacyanide in aqueous solutions: A picosecond X-ray absorption study

Lookup NU author(s): Professor Thomas Penfold



We present a picosecond Fe K-edge absorption study of photoexcited ferrous and ferric hexacyanide in water under 355 and 266 nm excitation. Following 355 nm excitation, the transient spectra for the ferrous and ferric complexes exhibit a red shift of the edge reflecting an increased electron density at the Fe atom. For the former, an enhanced pre-edge transition is also observed. These observations are attributed to the aquated [Fe(CN)5OH2]3− species, based on quantum chemical calculations which also provide structural parameters. Upon 266 nm excitation of the ferric complex, a transient reminiscent of the aquated species is observed (appearance of a pre-edge feature and red shift of the edge) but it is different from that obtained under 355 nm excitation. This points to a new reaction channel occurring through an intermediate state lying between these two excitation energies. Finally, 266 nm excitation of the ferrous species is dominated by the photooxidation channel with formation of the ferric complex as main photoproduct. However, we observe an additional minor photoproduct, which is identical to the 266 nm generated photoproduct of the ferric species, suggesting that under our experimental conditions, the pump pulse photooxidises the ferrous complex and re-excites the primary ferric photoproduct.

Publication metadata

Author(s): Reinhard M, Penfold TJ, Lima FA, Rittmann J, Rittmann-Frank MH, Abela R, Tavernelli I, Rothlisberger U, Milne CJ, Chergui M

Publication type: Article

Publication status: Published

Journal: Structural Dynamics

Year: 2014

Volume: 1

Pages: 024901-1-024901-12

Online publication date: 17/04/2014

Acceptance date: 07/04/2014

Date deposited: 02/10/2015

ISSN (electronic): 2329-7778

Publisher: American Institute of Physics


DOI: 10.1063/1.4871751


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