1 / 13

Angle resolved photoemission study of Sn/Pd(111) surface alloy phases

Angle resolved photoemission study of Sn/Pd(111) surface alloy phases. Mgr. Jiří Libra , Ph.D. KFPP MFF UK, Prague, Czech Republic. French-Czech seminar , Giens, 20-27 June 2009. Sn/Pd system investigation. KFPP, Prague: XPS, LEED, ISS

misty
Download Presentation

Angle resolved photoemission study of Sn/Pd(111) surface alloy phases

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. Angle resolved photoemission study of Sn/Pd(111) surface alloy phases Mgr.Jiří Libra, Ph.D. KFPP MFF UK, Prague, Czech Republic French-Czech seminar, Giens, 20-27 June 2009

  2. Sn/Pd system investigation • KFPP, Prague: • XPS, LEED, ISS • Angle resolved photoelectron spectroscopies: ARUPS, XPD • Kateřina Veltruská, Slavomír Nemšák, Tomáš Skála, Miloš Cabala, Vladimír Matolín • Elettra, Trieste: • SRPES, LEED • CO adsorption experiments • Jiří Libra, Peter Pira, Kateřina Veltruská, Miloš Cabala, Vladimír Matolín

  3. Model studies for catalytic applications CO adsorptions experiments - the strength of CO bonding to the surface depends on surface reconstruction - shifts of CO molecular orbitals SRPES measurement of valence band with primary photon energy of 130 eV. Solid lines represent spectra before CO adsorption, dashed after adsorption. The relative intensities of CO molecular orbitals normalised to the intensity of spectra obtained from clean Pd(111) surface after CO adsorption.

  4. Angle resolved UPS Pd(111) Sn/Pd (√3x√3)R30° Sn/Pd p(2x2)

  5. Structure models Sn Pd p(2x2) (√3x√3)R30° Sn/Pd (√3x√3)R30° surface alloy with no bulk equivalent 1/3 – 3 ML of Sn annealing Sn/Pd p(2x2) bulk Pd3Sn alloy >3 ML of Sn annealing ISS experiment A.F. Lee, C.J. Baddeley, M.S. Tikhov and R.M. Lambert 1997 Surf. Sci.373 195 Pd Sn • Our ISS measurement qualitatively confirmed surface model proposed by Lee Sn Pd

  6. Surface preparation Clean Pd(111) Sn/Pd (√3x√3)R30° Sn deposition of 0.8 nm Annealing to 400 C Sn/Pd p(2x2) Sn deposition of 4 nm Annealing to 400 C

  7. XPD (X-ray photoelectron diffraction) Pd(111), Pd 3d pattern

  8. XPD Sn 3d patterns p(2x2) typical bulk pattern (√3x√3)R30° similar like p(2x2) difference

  9. XPD pattern calculations Layer 1 Layer 2 Layer 3 Layer 4 Layer 5 sum of contributions experiment

  10. Sn/Pd(111) (√3x√3) Pd Sn layer 1st ? 2nd 3rd ? 4th ? Surface versus bulk structure

  11. Comparison of scattering properties of Pd and Sn atoms Sn/Pd Sn difference

  12. Layer 1 Layer 2 Layer 3 Layer 4 Layer 5 1+2 1+2+3 1+2+3+4 1+4 1+4+5 Experiment: All (1-5) 2 x 2 √3 x √3

  13. Conclusions bulk Pd3Sn alloy terminated by p(2x2) (√3x√3)R30° surface alloy Pd3Sn-like alloy formed by rest of deposited Sn atoms Sn Pd Sn/Pd (√3x√3)R30° Sn/Pd p(2x2) Sn/Pd (√3x√3)R30° surface consists of Pd2Sn surface alloy and some Sn atoms under surface, probably in layer 4 and deeper

More Related