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Surface Science @ Universidad Autónoma de Madrid

Surface Science @ Universidad Autónoma de Madrid. Roberto Otero On behalf of all the members of the Surface Science Laboratory @ Universidad Autónoma de Madrid. Nanosciences & Surface Science. Optical devices based on organic thin films. Molecular electronic devices. Introduction.

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Surface Science @ Universidad Autónoma de Madrid

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  1. Surface Science @ Universidad Autónoma de Madrid Roberto Otero On behalf of all the members of the Surface Science Laboratory @ Universidad Autónoma de Madrid

  2. Nanosciences & Surface Science Optical devices based on organic thin films Molecular electronic devices Introduction Functionalized surfaces for implant applications Nanomechanical biosensors

  3. Organic Optoelectronic Devices Example: Pentacene thin films Introduction Intensity (a.u.) 2θ (º) C. D. Dimitrakopoulos & P. L. Malefant, Advanced Materials14, 99 (2002)

  4. Thin Film Growth Introduction • For organic adsorbates: • 3D molecular structure (degrees of freedom) • Specificity in intermolecular interactions

  5. Nº of incident molecules/time × area = Ultra-High Vacuum (UHV) How long does it take for an atomically clean single-crystal surface to get dirty? Introduction At RT, P = 1 Atm, m = 4 uma, about 7.71 × 1027 molecules per second and square meter hit the surface. For Cu (100) (square lattice with lattice parameter 2.56 Å) this number equals 5 × 109 molecules/second and unit cell At P = 10-10 Torr, only 6 × 10-4 molecules per second and unit cell hit the surface, i.e. an average of 25 min are necessary to have all the unit cells hit by one molecule

  6. Ultra-High Vacuum (UHV) Introduction

  7. Ultra-High Vacuum (UHV) Introduction 20 × 20 nm2 O/Cu(110) PO = 10-8 Torr tframe = 20 s

  8. Experimental Techniques • Structure: • Real Space (STM) • Reciprocal Space (SXRD, TEAS) • Chemistry (XPS) • Electronic Structure (UPS, STS) • Other properties… magnetism? (SP-STM, SMOKE) Introduction

  9. Scanning Tunneling Microscopy and Spectroscopy

  10. Scanning Tunneling Microscopy (STM) STM

  11. Things to do in the lab when you have an STM… Atomic structure of solid surfaces with vertical pm resolution Diffusion of atomic adsorbates STM Morphology of epitaxial systems Atom-by-atom nanostructure fabrication Subnanometer-resolution electronic spectroscopy

  12. TIREMISU (TIme REsolved MIcroscopy of SUrfaces) José María Gallego Me STM Christian Urban David Écija Marta Trelka

  13. SITTA (Sistema Integral de Túnel y Técnicas de Análisis) Fabián Calleja STM Juan José Hinarejos Amadeo L. Vázquez de Parga

  14. STM/STS: Layer-Dependent Roughening Transition STM F. Calleja, M. C. G. Passeggi, Jr., J. J. Hinarejos, A. L. Vázquez de Parga, and R. Miranda, Phys. Rev. Lett. 97, 186104 (2006)

  15. Diffraction and the Reciprocal Space

  16. Elementary Diffraction Theory Diffraction Reciprocal space vector Wavelength ≈ Lattice parameter

  17. X-Rays: SXRD λ≈ 1 Å, E ≈ 12.3 keV → X Rays Large penetration depth!!! Real Space Reciprocal Space Diffraction

  18. Baby Chambers at Synchrotrons Diffraction Hamburg Me María José Capitán Jesús Álvarez

  19. Adenine Self-Assembly Diffraction

  20. Molecule Diffraction from Surfaces Diffraction

  21. The Atomic and Molecular Beam Diffraction Apparatus at LASUAM Guillaume Laurent Daniel Farías Diffraction Daniel Barredo Pablo Nieto

  22. H2 Diffraction In-plane and out-of-plane H2 diffraction spectra from Pt(111) recorded along the two main azimuths: Diffraction P. Nieto, E. Pijper, D. Barredo, G. Laurent, R.A. Olsen, E.J. Baerends, G.J. Kroes and D. Farías,Science 312, 86 (2006)

  23. Phonons on Pd(110): Surface Phonons Diffraction

  24. Chemical and Electronic Characterization

  25. Electrons in Solid Spectroscopy

  26. XRPS Spectroscopy Cristina Navío Jesús Álvarez María José Capitán

  27. X-Ray and UV Photoelectron Spectroscopy (XPS) Fe4N stoichiometry Fe 2p Spectroscopy N 1s 3000 Å x 3000 Å

  28. Other Techniques

  29. 1 W current sensor Field servo-loop-control power supply FREQ FIELD air gap ferrite Hall signal lens lens DSO polarizer fast photodiodes l/2 plate Wollaston prism analyser HeNe laser + – Dr. Julio Camarero SMOKE (Surface Magneto-Optical Kerr Effect) Magnetism

  30. Spin-Polarized STM Φ High current MT Ms Tip Sample Magnetism EF EF Amadeo L. Vázquez de Parga

  31. 8 9 7 8 6 9 9 8 8 9 7 0.16 nm 8 6 9 8 9 Spin-Polarized STM Sample: Mn/Fe(001) Mn grown at 370 K (<4x10-10mbar) STM image after depositing 7 ML Mn(001) film 0.14 nm Fe(001)-whisker Magnetism STS measured withclean W tip dI/dV curves dI/dV map at +0.2 V 140 x 150 nm2 Vs= - 0.5 V I=0.5 nA

  32. Spin-Polarized STM STS measured at room temperature withFe-coated W tip dI/dV curves STM image dI/dV map at +0.2 V 2.5 10 10 8 9 9 9 10 12 12 dI/dV [nA/V] 11 1.5 10 11 10 11 Magnetism 0.5 11 11 9 9 1.0 -1.0 -0.5 0.0 0.5 8 8 Sample voltage [V] 100 x 100 nm2 100 x 100 nm2 Vs= - 0.5V, I=0.5nA With the Fe-coated W tip alternating contrast with a clean W tip there is no contrast Reversed contrast with different Fe-coated W tips due to different tip magnetization

  33. 6.5 ML of Mn/Fe(001) Topography Measured at room temperature 80 x 80 nm2 I map at V=0.10 V Spin-Polarized STM Magnetism

  34. Conclusion • A multitechnique approach to address problems related with the growth and characterization of nanostructures

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