Charge transfer to solvent identified using dark channel fluorescence-yield L-edge spectroscopy

  • A Retraction to this article was published on 25 July 2017
  • This article was retracted on 25 July 2017

Abstract

Aqueous ions are central to catalysis and biological function and play an important role in radiation biology as sources of damage-inducing electrons. Detailed knowledge of solute–solvent interactions is therefore crucial. For transition-metal ions, soft X-ray L-edge spectroscopy allows access to d orbitals, which are involved in chemical bonding. Using this technique, we show that the fluorescence-yield spectra of aqueous ionic species exhibit additional features compared with those of non-aqueous solvents. Some features dip below the fluorescence background of the solvent and this is rationalized by the competition between the fluorescence yields of the solute and solvent species, and between the solute radiative (fluorescence) and non-radiative channels; in particular, electron transfer to the water molecules. This method allows us to determine the nature, directionality and timescale of the electron transfer. Remarkably, we observe such features even for fully ligated metal atoms, which indicates a direct interaction with the water molecules.

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Figure 1: Fluorescence-yield spectra in the L2,3-edge region of Fe3+ ions in different solvents and for different FeCl3 concentrations.
Figure 2: Fluorescence-yield spectra in the L2,3-edge region of iron in different molecular systems.
Figure 3: Comparison of the oxygen K-edge with the iron L3-edge fluorescence-yield spectra of aqueous solutions of FeCl3.

Change history

  • 29 June 2017

    We the authors are retracting this Article as we are unable to explain the presence of data in three of the spectra; namely, Figure 2a (hemin in ethanol) and Figure 2c ([Fe(bpy)3]2+ in water and in acetonitrile). The spectra in Figures 2a and 2c feature data in the 730 eV to 735 eV region that appear to have been duplicated from other regions of the spectra. We are unable to provide raw data for this region for any of the three spectra and we are unable to attempt to reproduce the spectra under the same conditions originally reported because the original beamline (U41-PGM) that we have used to conduct these experiments has been dismantled. The data integrity issues undermine our full confidence in the integrity of the study and we therefore wish to retract the Article.

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Acknowledgements

We thank F. de Groot for discussions. This work was supported by the Helmholtz-Gemeinschaft (the young investigator fund VH-NG-635), the Swiss National Science Foundation (grants 200021-116533/1 and IZK0Z2-126024) and the Swiss State Secretariat for Education and Research (COST CM0702). M.C. is grateful to the Alexander von Humboldt Foundation for support.

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E.F.A. conceived and designed the experiments, E.F.A, M.H.R.F. and K.M.L. performed the experiments, E.F.A., S.B. and M.C. analysed the data and E.F.A. and M.C. co-wrote the paper.

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Correspondence to Emad F. Aziz or Majed Chergui.

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The authors declare no competing financial interests.

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Aziz, E., Rittmann-Frank, M., Lange, K. et al. Charge transfer to solvent identified using dark channel fluorescence-yield L-edge spectroscopy. Nature Chem 2, 853–857 (2010). https://doi.org/10.1038/nchem.768

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