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Synchrotron Radiation Interaction with Matter; Different Techniques

Synchrotron Radiation Interaction with Matter; Different Techniques. Anders Nilsson. Stanford Synchrotron Radiation Laboratory. Why X-rays? VUV ?. What can we hope to learn?. Photon Interaction. Incident photon interacts with electrons Core and Valence. Cross Sections. Photon is

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Synchrotron Radiation Interaction with Matter; Different Techniques

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  1. Synchrotron Radiation Interaction with Matter; Different Techniques Anders Nilsson Stanford Synchrotron Radiation Laboratory Why X-rays? VUV? What can we hope to learn?

  2. Photon Interaction Incident photon interacts with electrons Core and Valence Cross Sections • Photon is • Adsorbed • Elastic Scattered • Inelastic Scattered • Electron is • Emitted • Excitated • Dexcitated Stöhr, NEXAFS spectroscopy Below 100 keV Photoelectric and elastic cross section dominates Spectroscopy-Scattering

  3. Detected Particles • EMITTED PARTICLE • Elastic Scattering X-Diffraction, Speckle • Inelastic Scattering X-ray Emission Spectroscopy • Electron Emission Photoelectron Spectroscopy • NO EMITTED PARTICLE • Photon Adsorbed X-ray Absorption Spectroscopy

  4. Diffraction Diffraction • X-ray diffraction • Photoelectron diffraction (PhD) • Extended X-ray Absorption Fine Structure (EXAFS) Long range X-ray diffraction Interference of many scattered photons Short range PhD and EXAFS Local scattering of electrons to nearest neighbor

  5. Spectroscopy Valence electrons Chemical Bonding Core electrons Non interacting Ionization Photoelectron Spectroscopy hn

  6. Core Levels-Atom Specific Information X-rays probes core levels Element Sensitive Chemical Shifts Hufner, Photoelectron Spectroscopy Stöhr et.al

  7. Core Level Spectroscopy Unoccupied states Fermi level Occupied states Core level

  8. Polarized X-rays Orientations and Directions Probing Charge orientations and Spin directions

  9. Polarization Effects in X-ray Absorption

  10. Resonant Processes

  11. Methods • X-ray Diffraction • Photoelectron Spectroscopy (PES) • Core level electron spectroscopy • Valence band photoemission • Resonant photoemission • Photoelectron Diffraction • X-ray Absorption Spectroscopy (XAS) • Near Edge X-ray Absorption Spectroscopy (NEXAFS) • Extended X-ray Absorption Fine Structure (EXAFS) • X-ray Magnetic Circular Dichroism (XMCD) • X-ray Emission Spectroscopy (XES) • Resonant Inelastic X-ray Scattering (RIXS) • Soft X-ray Scattering • Speckle

  12. Chemical Analysis • Chemical Identifications • Speciation • Quantitative analysis CO adsorption Cr(VI) on Iron oxides C1s, O1s and Pt4f XPS Cr L XAS

  13. Geometric Structure • Lattice parameters • Bond length • Molecular orientation Representation of Li structure at 44 Gpa pressure Diffraction pattern of of Li metal Local orientation of glycine on Cu(110) Two dimensional structure of glycine adsorbed on Cu(110) XAS spectra of glycine adsorbed on Cu(110)

  14. Electronic Structure • Electronic Structure • Band structure • Electronic properties in complex materials • Magnetism Angular resolved PES Measured band structure of quasicrystals Photoemission spectra of W

  15. Chemical Bonding • Electronic structure • Chemical Bonding • Molecular orbitals • Local Probing X-ray emission process Chemical picture of bonding Molecular orbital diagram XES spectra of N2 on Ni(100)

  16. Magnetism • X-ray magnetic circular dichroism (XCMD) • Element specific • Spin and orbital moments • Magnetic Information XMCD principle Ni L edge XAS spectrum and XMCD effect of Pt-Ni multilayer sample Pt-Ni Multilayer

  17. Dynamics • Dynamic scattering of coherent soft x-rays • Molecular fluctuations on the microsecond time scale • Free electron laser • Femtosecond phenomena Molecular fluctuations in liquid-crystal film FUTURE! Probe pulse at different delay time Dt

  18. Microscopy • Spectroscopy with spatial resolution • Spatial chemical speciation • Magnetic domains

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