Synchrotron X-ray Absorption Spectroscopy - Stanford Synchrotron ...
Synchrotron X-ray Absorption Spectroscopy - Stanford Synchrotron ...
Synchrotron X-ray Absorption Spectroscopy - Stanford Synchrotron ...
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What are near-edge spectra sensitive to?<br />
Trigonal vs. Digonal cuprous thiolate compounds<br />
Inspection of the chemical literature indicates that Cu(I) prefers two<br />
distinct coordination environments – linear two-coordinate (digonal)<br />
and planar three-coordinate (trigonal) coordination geometries, e.g.<br />
with thiolate ligands:<br />
SR<br />
Cu<br />
SR<br />
-<br />
SR<br />
2-<br />
RS Cu<br />
SR<br />
Cuprous thiolate metalloproteins form a very large group of diverse<br />
function. Both two and three coordinate examples are known.<br />
I. J. Pickering and G. N. George GEOL 498.3/898.3<br />
atom<br />
Isolated atom – degenerate<br />
p-orbital energies<br />
Ligand Field Splitting<br />
p x p y p z<br />
energy<br />
Molecule – ligand-field splitting,<br />
p-orbital degeneracy lifted<br />
I. J. Pickering and G. N. George GEOL 498.3/898.3<br />
What are near-edge spectra sensitive to?<br />
Trigonal vs. Digonal cuprous thiolate compounds<br />
Cu(I) is 3d 10 , so we expect no quadrupole transitions to the 3d<br />
manifold, and the lowest energy features in the near-edge should be<br />
1s→4p transitions. Let us consider the ligand field splitting of the 4p<br />
orbitals.<br />
x<br />
z<br />
digonal<br />
SR<br />
y Cu<br />
SR<br />
p x<br />
p z<br />
p y<br />
RS<br />
trigonal<br />
Cu<br />
SR<br />
SR<br />
I. J. Pickering and G. N. George GEOL 498.3/898.3<br />
p y<br />
p x<br />
p z<br />
RS<br />
p x<br />
Cu<br />
p y<br />
SR<br />
SR<br />
p z<br />
energy<br />
distorted trigonal<br />
p x<br />
pz py
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