Orthoaxial single crystal X-ray circular and linear dichroism of the 1s3d transition of 2NaCl6H2O: Measurement of the absolute values of the quadrupole and dipole contributions to the intensity of a pre-edge transition

We report the orthoaxial and axial X-ray circular dichroism spectra of a homochiral single crystal of {L-[Co(en)3]Cl3}2 · NaCl · 6H2O along with the linear dichroism of the same compound. The signs and magnitudes of the spectra confirm that the optical activity arises entirely from the interference between an electric quadrupole and electric dipole transition (E1E2 mechanism). By combining the results of the CD and LD spectra we have extracted the absolute values of the electric quadrupole and electric dipole contributions to the intensity of the 1s 3d transition and compare these to an ab initio calculation.