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

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. A detailed understanding of solute–solvent interactions is crucial to appreciating the important role aqueous ions play in various biological and catalytic processes. Now soft X-ray spectroscopy reveals new features in aqueous ion spectra that are due to solute–solvent interaction and electron transfer.

Cite this article

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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