1 / 16

EFN512M / EFN010F Molecular Spectroscopy and Reaction Dynamics

EFN512M / EFN010F Molecular Spectroscopy and Reaction Dynamics. Group II – 1st Presentation Scanning Tunneling Microscope Jingming Long, Nanna Rut Jónsdóttir, Kári Sveinbjörnsson & Guðfinnur Baldur Skæringsson Demonstration date: 16.09.10 Presentation date: 05.10.10. Contents.

prem
Download Presentation

EFN512M / EFN010F Molecular Spectroscopy and Reaction Dynamics

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. EFN512M / EFN010FMolecular Spectroscopy and Reaction Dynamics Group II – 1st Presentation Scanning Tunneling Microscope Jingming Long, Nanna Rut Jónsdóttir, Kári Sveinbjörnsson & Guðfinnur Baldur Skæringsson Demonstration date: 16.09.10 Presentation date: 05.10.10

  2. Contents

  3. Principals of the STM • Developed in 1982 • Based on the tunneling effect and the electrical conductance between two electrodes. • The electron travels through a potential barrier. • Low current (10 pA – 1nA) • Requires ultra-high vacuum

  4. Principals of the STM • Movement controled with a Piezo-material like BaTiO3. • Very sensitive to vibrations. • Different images of the same surface due to a changing electron statesor or modifications of the tip. • Pros: No sample damage, atomic resolution. • Cons: Limited to conductors/semi-conductors, a difficult process to perfom.

  5. Graphite • An allotrope of carbon. • One of the most studied materials with STM.

  6. The anomalous contrast (Moiré pattern) of the picture suggest a misoriented lower layer of graphite.

  7. STM Images

  8. Graphene • A stable 2D crystal, consisting of carbon. • Good thermal and electrical conductivity. • 200x stronger than steel. • Applications include us in: • Single Molecule Gas Detection • Nanoribbons • Transistors • Ultracapacitors • Biodevices

  9. STM • Graphene layer with different supports.

  10. STM Graphene Layer

  11. Summary • STM based on e- tunneling through gap between two electrodes. • Graphite used as calibration. • Moiré effect suggest unparallel layers. • Graphene stable 2D crystal where every C is seen.

  12. References • Anomalous superperiodicity in scanning tunneling microscope images of graphite. M. Kuwabara, D. R. Clarke, and D.A. Smith. Appl. Phys. Lett., Vol. 56, No. 24, 11 June 1990. • On the STM imaging contrast of graphite : towards a true atomic resolution. F. Atamny et al. Phys. Chem. Chem. Phys., 1999, 1, 4113-4118. • High-resolution scanning tunneling microscopy imaging of mesoscopicgraphene sheets on an insulating surface. Elena Stolyarova, Kwang Taeg Rim, Sunmin Ryu, Janina Maultzsch, Philip Kim, Louis E. Brus, Tony F. Heinz, Mark S. Hybertsen, and George W. Flynn. PNAS, May 29, 2007, vol. 104, no. 22, 9209-9212. • The rise of graphene. A.K. Geim and K. S. Novoselov. Nature Materials | VOL 6 | MARCH 2007.

  13. References • Electron states of mono- and bilayergraphene on SiC probed by scanning-tunneling microscopy. P. Mallet, F. Varchon, C. Naud, L. Magaud, C. Berger,and J.-Y. Veuillen. Physical Review B 76, 041403(R) (2007). • Scanning tunneling microscopy of graphene on Ru(0001). S. Marchini, S. Günther, and J. Wintterlin*. Physical Review B 76, 075429 (2007). • Lee, C. et al. (2008). "Measurement of the Elastic Properties and Intrinsic Strength of Monolayer Graphene". Science321 (5887)

  14. Thank you

More Related