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David Ramaker Professor Dept of Chemistry ramaker@gwu 202-994-6034

David Ramaker Professor Dept of Chemistry ramaker@gwu.edu 202-994-6034. Universiteit Utrecht. X-ray Absorption Spectrocopy: A Unique and Versatile Probe. David Ramaker, Chemistry -Former: Maggie Teliska and Frances Scott -Current: Danny Gatewood, Badri Shyam.

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David Ramaker Professor Dept of Chemistry ramaker@gwu 202-994-6034

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  1. David RamakerProfessorDept of Chemistryramaker@gwu.edu202-994-6034

  2. Universiteit Utrecht X-ray Absorption Spectrocopy: A Unique and Versatile Probe David Ramaker, Chemistry -Former: Maggie Teliska and Frances Scott -Current: Danny Gatewood, Badri Shyam Sanjeev Mukerjee, Northeastern-Students: Joe, Tom, VivekChristina Roth, TU-DarmstadtHelmut Fuess. TU-DarmstadtDiek Koningsberger, Utrecht, NL - Bill O’Grady, NRL- Karen Swider-Lyons, NRL

  3. XAFS Set-Up Monochromator Sample Ref. material Synchrotron 3 Ionization chambers:Intensity of initial, intermediate and final light Anything that x-rays can pass through we can study

  4. Schematic illustration of techniques EXAFS AXAFS EXAFS c Normalization Background Removal Fourier Transform E(eV) E(eV) k(Å-1) R(Å) XANES (ads/Pt) (Pt)  Normalization Background Removal E(eV) E(eV) E(eV) E(eV)

  5. Information we can gather • Protein denaturation • Molecular adsorption sites and coverage on surfaces • Bond lengths and coordination numbers • Atom oxidation states • Metallic character of nanoparticles

  6. Applications 1. BiomaterialsS K edge in proteins. Cell interaction with hydrophilic/hydrophobic surfaces (protein denaturation)2. Surfaces: electronic materials, SiC3. Corrosion of Aluminum oxide4. Zeolite structure and catalysis 5. Homogenous catalysis: allyl/Pd complexes 6. Heterogeneous catalysis: Benzene hydrogenation on supported Pt clusters7. Electrocatalysis and fuel cells: 8. Metal/insulator transition in Pt nanoparticles

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