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|Title:||ALS-CXRO Seminar Series: Wayne Stolte|
|When:||09/17/2013 1:00 PM - 2:00 PM|
|Description:||Presented by: |
Wayne Stolte (LBNL)
"Polarized X-ray Emission in the Tender X-ray Region"
Polarization-dependent X-ray emission has been shown to be a probe of molecular field effects on the electronic structure of isolated molecules. This is a complementary approach to electron spectroscopy because it probes the neutral molecular states. I will be discussing several recent results from data obtained on beamline 9.3.1, with its unique polarized X-ray emission spectrometer.
Combined with a theoretical analysis we have discovered that the linear dichroism observed in Cl 2p resonant inelastic x-ray scattering (RIXS) following Cl 1s excitation in several chlorine containing small molecules as being due to molecular-field effects, including single-triplet exchange. This indicates that polarized RIXS can be a direct probe of spin-orbit-state populations. Further theoretical analysis based upon this result yielded a new approach connecting electronegativity to the relative weight of the 2pz spin-orbit component, one of the derived spectroscopic population parameters.
We experimentally observed interference effects in elastic x-ray scattering from gas-phase HCl in the vicinity of the Cl K edge. Comparison to theory identifies these effects as interference effects between non-resonant elastic Thomson scattering and resonant Raman scattering. The results indicate the non-resonant Thomson and resonant Raman contributions are of comparable strength. The measurements also exhibit strong polarization dependence, allowing an easy identification of the resonant and non-resonant contributions.