Reply to 'Dark channel fluorescence...' and 'Dips and peaks...'

State-dependent electron delocalization dynamics at the solute-solvent interface: soft-x-ray absorption spectroscopy and ab initio calculations

Nonradiative decay channels in the L-edge fluorescence yield spectra from transition-metal-aqueous solutions give rise to spectral distortions with respect to x-ray transmission spectra. Their origin is unraveled here using partial and inverse partial fluorescence yields on the microjet combined with multireference ab initio electronic structure calculations. Comparing Fe2+, Fe3+, and Co2+ systems we demonstrate and quantify unequivocally the state-dependent electron delocalization within the manifold of d orbitals as one origin of this observation.

Ligand discrimination of myoglobin in solution: an iron L-edge X-ray absorption study of the active centre

Iron L-edge X-ray absorption spectra of the active centre of myoglobin in the met-form, in the reduced form and upon ligation to O₂, CO, NO and CN are presented.

Dissecting Local Atomic and Intermolecular Interactions of Transition-Metal Ions in Solution with Selective X-ray Spectroscopy

Determining covalent and charge-transfer contributions to bonding in solution has remained an experimental challenge. Here, the quenching of fluorescence decay channels as expressed in dips in the L-edge X-ray spectra of solvated 3d transition-metal ions and complexes was reported as a probe. With a full set of experimental and theoretical ab initio L-edge X-ray spectra of aqueous Cr(3+), including resonant inelastic X-ray scattering, we address covalency and charge transfer for this prototypical transition-metal ion in solution. We dissect local atomic effects from intermolecular interactions and quantify X-ray optical effects. We find no evidence for the asserted ultrafast charge transfer to the solvent and show that the dips are readily explained by X-ray optical effects and local atomic state dependence of the fluorescence yield. Instead, we find, besides ionic interactions, a covalent contribution to the bonding in the aqueous complex of ligand-to-metal charge-transfer character.