Otto Stern (Sohrau 1888 – Berkeley 1969) Nobel Laureate 1943 - PowerPoint PPT Presentation

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Otto Stern (Sohrau 1888 – Berkeley 1969) Nobel Laureate 1943

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  1. Otto Stern (Sohrau 1888 – Berkeley 1969) Nobel Laureate 1943

  2. Otto Stern, O.R. Frisch, I. Estermann (Hamburg, 1929-1933) He a NaCl(001)

  3. “These experiments are of interest not only because of their confirmation of the predictions of quantum mechanics, but also because they introduce the possibility of applying atom diffraction to investigations of the atomic constitution of surfaces.” (T. M. Johnson, Phys. Rev. 37 (1931) 847).

  4. Bound-state resonances Frisch-Stern (1933) I00 J. E. Lennard-Jones and A. F. Devonshire, Nature 137 (1936) 1069.

  5. Gas – Surface Interactions: - energy transfer - sticking (adsorption) INELASTIC SCATTERING INELASTIC RESONANCES Lattice vibrations (phonons) J.M. Jackson and N.F. Mott, Proc. Roy. Soc. A 137 (1932) 703: Quantum DWBA

  6. L.D. Landau, Phys. Z. Sowjet. 8 (1935) 489. B.L. Bonch-Bruevich, Usp. Fiz. Nauka 40 (1950) 369 Classical Rarified Gas Dynamics Supersonic Molecular Beams

  7. Supersonic nozzle beam sources

  8. v

  9. High-resolution diffraction Supersonic He-atom beam sources Time-of-flight spectroscopy

  10. J. P. Toennies: HUGO (MPI-SF, Goettingen)

  11. Angular distributions Diffraction • Inelastic processes: • inelastic bound state resonances - kinematical focussing • - surfing

  12. Time of Flight (TOF) Inelastic scattering Phonons via the mechanical action (Pauli repulsion) on the electron density Phonon dispersion curves Forces between atoms Forces between ions and electrons (electron-phonon interaction) & electronic susceptibility

  13. inelastic He atom scattering excites phonons phonon excitations probe interatomic forces

  14. Surface waves Lord Rayleigh (1887) Irpinia 1980 (Polo Sismico Alberto Gabriele, FCCSEM Erice)

  15. Surface phonons 1: from 3D lattice to slab

  16. interatomic potential force constant matrix harmonic eq. of motion rl r(l1 l2 l3,) = l1a1 +l2a2 +l3a3+ d() 3D rl r(l1 l2 l3,) = l1a1 +l2a2 + d(l3,) 2D slab Bloch waves secular equation

  17. …to a slab of Nz layers Surface phonons 2: from one monolayer…

  18. TOF spectrum Energy-transfer spectrum scan curves for 90° geometry

  19. HAS versus theory NaF(001) LiF(001) theory: Green Function surface dynamics + DWBA scattering theory end of lecture 3

  20. Longitudinal resonance Rayleigh wave Metals: Skin & Bones I Cu(111) HAS

  21. Anomalous longitudinal resonance Cu(111) HAS data C. Kaden et al. PRB (1992)

  22. Cu(001) a giant resonance G. Benedek et al. PRB 1993

  23. There is something fundamental in the anomalous longitudinal resonance A feature common to all metal surfaces  A strong amplitude in HAS but weak in EELS  Unphysical fitting with force-constant models

  24. The Multipole Expansion (ME) Method Equilibrium:

  25. Adiabatic condition Secular equation Dynamic electron density oscillations Non-local dielectric response (susceptibility)

  26. Density-functional Hellmann-Feynman vs. Multipole expansion ynk Kohn-Sham wavefunctions:

  27. parametrized ME method

  28. Ion-core displacements Electron density oscillations ME DFPT

  29. Metals: Skin & Bones II

  30. HAS  hole-electron pairs! 1D conductor electron-hole excitations Peierls instability

  31. The Helium-3 Spin-Echo Spectroscopy P. Fouquet, A.P. Jardine, S. Dworski, G. Alexandrowicz, W. Allison and J. Ellis "Thermal energy 3He spin-echo spectrometer for ultrahigh resolution surface dynamics measurements“ Rev. Sci. Inst. 76, 053109 (2005).

  32. The Cavendish He3 Spin-Echo Apparatus

  33. First tests for He3 Spin-Echo: • Bound states of He3 on LiF(001) • Surface Transport Measurements using Quasi-elastic Helium Atom Scattering (QHAS) back to Frisch & Stern! A.P. Jardine, S. Dworski, P. Fouquet, G. Alexandrowicz, G.Y.H. Lee, D.J. Riley, J. Ellis, W. Allison, "Ultrahigh resolution spin-echo measurement of surface potential energy landscapes", Science 304, 1790-1793 (2004).

  34. atom microscope 4He gas jets atom interferometry cluster, droplets at 0.37 K 4He liquid jets nano-scale superfluididity targets for high-energy physics targets for laser accelerators (e.g., for hadrotherapy) superfluid 4He (p-H2) clusters inside 3He droplets jets from expansion of solid 4He: the geyser effect

  35. cluster beam cluster assembled film Grenoble - 9 SUPERSONIC CLUSTER BEAM DEPOSITION at the Department of Physics, University of Milano TOF-MS CHAMBER DEPOSITION CHAMBER SOURCE CHAMBER quartz MB sample manipulator He line PMCS substrate time of flight mass spectrometer to pulsed power supply target 2000 l/s diff. pump 700 l/s diff. pump 500 l/s turbo pump

  36. something more on inelastic atom scattering: Giorgio Benedek J. Peter Toennies Helium Atom Scattering Spectroscopy of Surface Phonons Springer-Verlag Berlin Heidelberg New York 2007 end of lecture 4

  37. Bibi Bortolani JPT