Molecular adsorbates on surfaces

Adsorption of Adenine on Cu(110)
(Geoffrey Stenuit and Paolo Umari)

First-Principles calculations are peformed to study the interactions between nucleic acids and metallic surfaces. In particular, the adsorption of adenine (C5N5H5) on Cu(110) surface is investigated through density functional theory. For several adsorption configurations the XPS shifts are calculated and compared to the experimental data provided by Kevin Prince's group.

In collaboration with:

  • ELETTRA - MS and GP beamlines (K. C. Prince, O. Plekan and V. Feyer)

Core level shifts of undercoordinated surface atoms and adsorbates
(S. de Gironcoli)

Measurements of core-level binding energy shifts of surface atoms and adsorbates carry a wealth of information on the local chemical and geometrical environment, but the precise interpretation is often problematic and relies on fitting procedures. A firmer interpretation of these data has been possible by the theoretical core-level spectroscopy performed in the Theory@Elettra group. In particular, these studies allowed to identify and monitor the presence of low-coordinated defects, such as isolated Rh adatom or dimers on a clean Rh (001), and to address the local changes in electronic structure induced by molecular species such as nitrogen, carbon and sulfur adsorbed on the metallic surface.

In collaboration with:

  • ELETTRA - SuperESCA beamline (L. Bianchettin and A. Baraldi)
  • CNR-INFM TASC (E. Vesselli, G. Comelli and R. Rosei)

Laura Bianchettin, Alessandro Baraldi, Stefano de Gironcoli, Erik Vesselli, Silvano Lizzit, Luca Petaccia, Giovanni Comelli, and Renzo Rosei
Core level shifts of undercoordinated Pt atoms
J. Chem. Phys. 128, 114706 (2008)

Alessandro Baraldi, Erik Vesselli, Laura Bianchettin, Giovanni Comelli Silvano Lizzit, Luca Petaccia, and Stefano de Gironcoli
The (1×1)hexagonal structural transition on Pt(100) studied by high-energy resolution core level photoemission
J. Chem. Phys. 127, 164702 (2007)

Laura Bianchettin, Alessandro Baraldi, Erik Vesselli, Stefano de Gironcoli, Silvano Lizzit, Luca Petaccia, Giovanni Comelli, and Renzo Rosei
Experimental and Theoretical Surface Core Level Shift Study of the S-Rh(100) Local Environment
J. Phys. Chem. C 111, 4003, (2007)

Laura Bianchettin and Alessandro Baraldi, Stefano de Gironcoli, Silvano Lizzit and Luca Petaccia, Erik Vesselli, Giovanni Comelli, and Renzo Rosei
Geometric and electronic structure of the N/Rh(100) system by core-level photoelectron spectroscopy: Experiment and theory
Phys. Rev. B 74, 045430 (2006)

Theoretical study of surface strain and self-assembling at metal surfaces
(N. Stojić and N. Binggeli)

Motivated by recent interesting results by nanospectroscopy group at Elettra, we are studying adsorbate-induced surface stress and the subsequent restructuring of the surface. First-principles calculations of surface stress are challenging and so far only a few comparisons with experiment are available. Therefore, our efforts are directed towards a better understanding of the factors that affect the comparison between theoretical results and surface-elasticity measurements.
In collaboration with:

  • ELETTRA - Nanospectroscopy beamline

T. O. Menteş, N. Stojić, N. Binggeli, M. A. Niño, A. Locatelli, L. Aballe, M. Kiskinova, and E. Bauer
Strain relaxation in small adsorbate islands: O on W(110)
Phys. Rev. B 77, 155414 (2008)

Core and valence TDDFT studies of bulk, nanostructured materials and surface adsorbed molecules
(G. Fronzoni, M. Stener, D. Toffoli, and P. Decleva)

The regular TiO2 (110) surface (rutile) has been simulated with a Ti19O32 cluster. The not chemically complete Ti and O atoms have been saturated by means of pseudo-hydrogen atoms with fractional nuclear charges (H’ Z=4/3, H” Z=2/3, small grey balls in the figure (panel c) of the cluster employed in the calculation). When a 2p core electron is excited to virtual bound levels, the XAS spectrum consists of transitions to two closely related manifold of excited states converging to the 2p3/2 (L3) and 2p1/2.(L2) ionization thresholds, which are separated in energy by the Spin-Orbit (SO) splitting of the core hole ( panel b of the figure shows the SO splitting of the initial core hole state and the SO calculated and experimental values) The comparison with the experiment is very satisfactory.