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Istv á n Hargittai Budapest University of Technology and Economics

Istv á n Hargittai Budapest University of Technology and Economics and Hungarian Academy of Sciences Gas-phase Electron Diffraction INTERNATIONAL SCHOOL OF CRYSTALLOGRAPHY 36thCourse: ELECTRON CRYSTALLOGRAPHY: NOVEL APPROACHES FOR STRUCTURE DETERMINATION OF NANOSIZED MATERIALS

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Istv á n Hargittai Budapest University of Technology and Economics

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  1. István Hargittai Budapest University of Technology and Economics and Hungarian Academy of Sciences Gas-phase Electron Diffraction INTERNATIONAL SCHOOL OF CRYSTALLOGRAPHY 36thCourse: ELECTRON CRYSTALLOGRAPHY: NOVEL APPROACHES FOR STRUCTURE DETERMINATION OF NANOSIZED MATERIALS ERICE, SICILY: JUNE 9-20, 2004

  2. Two-Volume Treatise on Gas-Phase Electron Diffraction

  3. CO2 Curves from Gas-Phase Electron Diffraction

  4. Brief History I • 1912-15 X-ray crystallography, Laue, the Braggs, Debye • 1924 de Broglie (wave nature of moving electrons) • 1927 Davisson & Germer, G.P. Thomson solid-phase electron diffraction • 1930 Mark and Wierl, first GED experiment • 1932 James, molecular vibrations • 1935 Pauling & Brockway, f(r)

  5. Brief History II • 1937-39-49 Finbak, Debye, Karle and Karle rotating sector-microphotometer method • 1950s modern experimental apparatus • 1955 Bartell the physical meaning of geometrical parameters • Last decades combined and concerted application of various techniques • Fine effects (relativistic, Jahn-Teller, etc.) • Increasingly, quantum chemical calculations

  6. Gas-phase electron diffraction experiment

  7. Combined gas-phase electron diffraction/mass-spectrometric experiment

  8. Total Intensity Distribution and “Background”

  9. Molecular Intensities

  10. Molecular Intensities

  11. Probability Density Distributions

  12. Scheme of Least-Squares Refinement

  13. C6H3F3 and C6H3Cl3: Probability Density Distributions

  14. Jahn-Teller EffectEdward Teller (1908-2003) “A nonlinear, symmetric molecule with an orbitally degenerate electronic state is unstable and gets distorted, thereby removing the electronic degeneracy, until a nondegenerate ground state is achieved.” Jahn, H.A.; Teller, E. Proc. R. Soc. London A1937, 161, 220.

  15. Jahn-Teller Effect MnF3 D3h C2vC2v Hargittai, M. et al. J. Am. Chem. Soc.1997, 119, 9042.

  16. MnF3 electron diffraction Hargittai, M. et al. J. Am. Chem. Soc.1997, 119, 9042.

  17. HS-CH2-CH2-SH Conformational Analysis

  18. Estimating Mole Ratios

  19. REPRESENTATIONS OF AVERAGE STRUCTURES

  20. Comparison with Other Techniques • Microwave spectroscopy • X-ray crystallography • Quantum chemical calculations • NMR spectroscopy • Vibrational spectroscopy • Mass spectrometry • Qualitative models

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