Regensburg 2007 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 17: Poster Session I (Nanostructures at Surfaces; Metal Substrates: Epitaxy and Growth; Methods: Scanning Probe Techniques; Phase Transitions)

O 17.31: Poster

Montag, 26. März 2007, 17:30–20:30, Poster C

Interaction of nitric oxide with the clean and oxygen-covered Re(10-10) surface — •Viktor Scherf, Christian Pauls, and Klaus Christmann — Institut für Chemie und Biochemie, FU Berlin, Germany

The molecular and dissociative adsorption of nitric oxide (NO) on the Re(10-10) surface was studied in UHV between 120 and 1200 K by means of LEED, HREELS, TDS, and work function change (Δ Φ) measurements. On the initially oxygen-free Re surface and at 120 K, a minor fraction of NO spontaneously dissociates into O_ad and N_ad, while the majority of NO adsorbs in two molecular α states. Exposing NO at about 490 K, however, leads exclusively to the dissociation products. TDS exhibits both associative (first-order kinetics) and dissociative (second-order kinetics) desorption states, the work function increases (at 120 K) by 750 meV, and the N=O stretching vibrations ν_NO appear at 1706 cm⁻¹ (α₁ state) and at 1468 cm⁻¹ (shoulder, α₂ state) and are associated with NO held in the terminal and the bridge position, respectively. Pre-adsorption of oxygen ((1x5)-O-phase) facilitates molecular NO adsorption and causes a decrease of Δ Φ, thus reflecting a strong influence of co-adsorbed O on the NO-Re bonding chemistry. Our data are discussed and compared with similar investigations reported in the literature for Ru and Pt surfaces.