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The adsorption of 2-mercaptobenzothiazole (2-MBT) vapor on a Cu(111) surface under ultra-low pressure was investigated. For an exposure of 45 L at 150 °C, a Moiré pattern was observed as a result of the superposition of an underlying (3×3)R30° structure and an outer layer compressed by 18% and rotated by 1.2°. The Moiré pattern was rich in S bonded to Cu as a result of molecular decomposition and partial desorption and was transformed to a (7×7)R19.1° structure when the sample temperature was increased above 250 °C during deposition. This pre-adsorbed Moiré structure led to the sharp decrease of the oxidation kinetics, which better protects copper against corrosion than the non-ordered 2-MBT monolayer formed at room temperature. Upon further exposure to 2-MBT at room temperature, an equivalent monolayer of the molecule was adsorbed on the Moiré structure at saturation whereas a multilayer was formed for the direct deposition on Cu(111) at room temperature.

The adsorption of 2-MBT organic inhibitor on copper and its effects on anodic oxide growth in NaOH were investigated using cyclic voltammetry, X-ray photoelectron spectroscopy, and time-of-flight secondary ion mass spectrometry techniques. It is shown that 2-MBT significantly impedes the growth of the Cu(I) oxide by forming a multilayered organic film on the surface. A major factor influencing the formation and properties of the organic barrier layer is the presence and structure of the interfacial native oxide on which it forms. The 2-MBT multilayer bonds to the metallic copper substrate mostly via its sulphur atoms along with a small fraction of the nitrogen atoms also bonding to the metallic substrate. Additionally, there is an interaction between the inhibitor molecules and copper released from the surface to form metal-organic complexes in the outer layers of the thicker films.

The structure of the γ-TiAl(111) alloy surface was studied with combined experimental and theoretical approaches. The experimental scanning tunneling microscopy (STM) images indicate surface reconstruction with a (2 × 2) superstructure as a result of Al depletion of the alloy surface after preparation. The atomic protrusions form a zigzag pattern oriented along the direction of the shorter surface unit vector of the (2 × 2) supercell, that is, the [101̅] direction. The theoretical investigations performed with molecular dynamics in combination with simulated annealing based on the density functional theory (DFT) show that the surface starts to reconstruct at temperatures higher than 950 K, in agreement with the experimental annealing temperature. Geometric analysis and simulated STM images obtained from periodic DFT calculations show that the atomic protrusions forming the zigzag patterns correspond to Al atoms of the reconstructed topmost plane. The persistence of the reconstructed structure up to the simulated melting temperature of 1800 K shows the high stability of Al vacancies injected in the topmost plane of the alloy.

For the first time the surface of brass (Cu−Zn alloy) and its chemistry have been characterized by scanning tunneling microscopy/spectroscopy at the subnanometer (atomic) scale. The comparative results obtained on Cu 70Zn 30(111) and Cu(111) single-crystal surfaces evidence the random distribution of Zn atoms substituted to Cu atoms at the extreme surface of brass, the Zn-depleted concentration in the topmost layer of the alloy and the associated modifications of the surface density of states. The initial stages of interaction with oxygen and sulfur highlight the role of Zn in the surface chemistry. The reactivity becomes governed by the chemical defects (Zn atoms) introduced by alloying. The nucleation mechanism and the nature of the surface oxide compounds are modified. Surface reconstruction is promoted in the reaction with sulfur, and S vacancies are introduced in the surface sulfide compounds. The data are relevant for the detailed understanding of the effect of alloying a noble or seminoble metal matrix with a more reactive chemical element on the growth mechanisms of adhesion conversion layers and on corrosion mechanisms by dealloying.

Scanning tunneling spectroscopy has been applied to characterize the electronic properties of the granular and intergranular sites of the passive film grown on Ni(111) single-crystal surfaces in acid solution. The passive film, essentially consisting of NiO, shows p-type grains (valence band edge at 0.54 ± 0.03 eV below Fermi level) with unoccupied Ni 3d surface states at 0.5–1.5 eV above Fermi level in the bandgap. At grain boundaries, the p-type semiconductivity is attenuated as evidenced by a downward shift of 0.12 ± 0.06 eV of the valence band edge, and the density of surface states is markedly reduced, both effects indicating the presence of oxygen vacancies in these sites. The dominant point defect in the film is metallic vacancies but oxygen vacancies attenuate locally the resulting p-type property at the grain boundaries. The implications of these local electronic properties on oxidative and reductive electronic transfer and on the corrosion resistance are discussed. The oxygen vacancies at intergranular boundaries imply local changes of the properties of anionic mass transport through the passive film and enhancement of Cl−adsorption and/or penetration, which is consistent with the view of passive film grain boundaries playing a key role in passivity breakdown.