| 1. |
- Borga, M, et al.
(författare)
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Structure and dynamics of Na adsorption on Al(100)
- 2002
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Ingår i: 7th International Conference on Nanometer-Scale Science and Technology and 21st European Conference on Surface Science.
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Konferensbidrag (refereegranskat)abstract
- The adsorption of 0.2 monolayers (ML) of Na on Al(100) has been studied both experimentally, using low energy electron diffraction (LEED) and high resolution core level spectroscopy (HRCLS), and theoretically, using density functional theory (DFT). Two ordered phases are found: Islands of c (2×2) symmetry with Na atoms occupying four-fold hollow sites result from low temperature deposition and a (√5×√5)R27° structure with Na in surface substitutional sites is formed by annealing of the low temperature island structure at 300 K and subsequent cooling below 230 K. The (√5×√5)R27° structure undergoes a reversible order-disorder phase transition at ~230 K. To investigate this phase transition further, we performed additional DFT calculations for a wide range of coverages (from 0.0625 to 0.5 ML), for adsorption in both hollow and substitutional sites, from which we extract interaction energies which are used in a lattice gas Monte Carlo simulations
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| 2. |
- Lundgren, Edvin, et al.
(författare)
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Kinetic hindrance during the initial oxidation of Pd(100) at ambient pressures
- 2004
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Ingår i: Physical Review Letters. - 1079-7114. ; 92:4
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Tidskriftsartikel (refereegranskat)abstract
- The oxidation of the Pd(100) surface at oxygen pressures in the 10(-6) to 10(3) mbar range and temperatures up to 1000 K has been studied in situ by surface x-ray diffraction (SXRD). The results provide direct structural information on the phases present in the surface region and on the kinetics of the oxide formation. Depending on the (T,p) environmental conditions, we observe either a thin (root5 x root5)R27degrees surface oxide or the growth of a rough, poorly ordered bulk oxide film of PdO predominantly with (001) orientation. By either comparison to the surface phase diagram from first-principles atomistic thermodynamics or by explicit time-resolved measurements we identify a strong kinetic hindrance to the bulk oxide formation even at temperatures as high as 675 K.
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| 3. |
- Lundgren, Edvin, et al.
(författare)
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The intermetallic oxidation of Pd(100)
- 2002
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Ingår i: 7th International Conference on Nanometer-Scale Science and Technology and 21st European Conference on Surface Science.
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Konferensbidrag (refereegranskat)abstract
- We have studied the Pd(100)-(√5×√5)-O structure formed by adsorption of 0.8 ML of oxygen by Scanning Tunneling Microscopy (STM), High Resolution Core Level Spectroscopy (HRCLS) and Density Functional Theory (DFT). We show that a recent tensor Low Energy Electron Diffraction (LEED) analysis of the Pd(100)-(√5×√5)-O structure is incompatible with our results from this structure. A new model that is consistent with our results is suggested. We also demonstrate the existence of dislocations observed by STM in the Pd(100)-(√5×√5)-O structure and explain their geometrical arrangement
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| 4. |
- Todorova, M, et al.
(författare)
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The Pd(100)-(root 5 x root 5)R27 degrees-O surface oxide revisited
- 2003
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Ingår i: Surface Science. - 0039-6028. ; 541:1-3, s. 101-112
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Tidskriftsartikel (refereegranskat)abstract
- Combining high-resolution core-level spectroscopy, scanning tunneling microscopy and density-functional theory calculations we reanalyze the Pd(100)-(root5 x root5)R27degrees-O surface oxide phase. We find that the prevalent structural model, a rumpled PdO(001) film suggested by previous low energy electron diffraction (LEED) work [Surf. Sci. 494 (2001) L799], is incompatible with all three employed methods. Instead, we suggest the two-dimensional film to consist of a strained PdO(101) layer on top of Pd(100). LEED intensity calculations show that this model is compatible with the experimental data of Saidy et al. (C) 2003 Elsevier B.V. All rights reserved.
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| 5. |
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