2 research outputs found
Chemical Bonding in Aqueous Ferrocyanide: Experimental and Theoretical X‑ray Spectroscopic Study
Resonant inelastic X-ray scattering
(RIXS) and X-ray absorption
(XA) experiments at the iron L- and nitrogen K-edge are combined with
high-level first-principles restricted active space self-consistent
field (RASSCF) calculations for a systematic investigation of the
nature of the chemical bond in potassium ferrocyanide in aqueous solution.
The atom- and site-specific RIXS excitations allow for direct observation
of ligand-to-metal (Fe L-edge) and metal-to-ligand (N K-edge) charge-transfer
bands and thereby evidence for strong σ-donation and π-backdonation.
The effects are identified by comparing experimental and simulated
spectra related to both the unoccupied and occupied molecular orbitals
in solution
Transition-Metal Nanoparticle Oxidation in a Chemically Nonhomogenous Environment Revealed by 2p3d Resonant X‑ray Emission
X-ray absorption spectroscopy (XAS)
is often employed in fields
such as catalysis to determine whether transition-metal nanoparticles
are oxidized. Here we show 2p<sub>3/2Â </sub>XAS and 2p3d resonant
X-ray emission spectroscopy (RXES) data of oleate-coated cobalt nanoparticles
with average diameters of 4.0, 4.2, 5.0, 8.4, and 15.2 nm. Two particle
batches were exposed to air for different periods of time, whereas
the others were measured as synthesized. In the colloidal nanoparticles,
the cobalt sites can have different chemical environments (metallic/oxidized/surface-coordinated),
and it is shown that most XAS data cannot distinguish whether the
nanoparticles are oxidized or surface-coated. In contrast, the high-energy
resolution RXES spectra reveal whether more than the first metal layer
is oxidized based on the unique energetic separation of spectral features
related to the formal metal (X-ray fluorescence) or to a metal oxide
(d-d excitations). This is the first demonstration of metal 2p3d RXES
as a novel surface science tool