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We have studied the near surface defects of the delta-doped B:Si(111)-(√3 × √3)R30° system using a combination of scanning tunneling microscopy, non-contact atomic force microscopy, Kelvin probe force spectroscopy, total energy DFT, and STM theoretical simulations. We positively identify and characterize two near surface defects: the adatom vacancy and a B substitutional defect located in the second Si bilayer. We also confirm the assignment of the dangling-bond defect. Additionally, the influence that the subsurface B dopants have on the surface electronic structure, the modulation of the surface potential and the chemical activity of the surface is investigated.

The adsorption of ethylene on the bridge adatom–restatom position of the Si(111)–7 × 7 surface was studied with scanning tunneling microscopy, photoelectron spectroscopy, and theoretical calculations. The electronic structure and the corresponding vibrational states were calculated for a single molecule adsorbed in different binding sites located within the 7 × 7 unit cell. We found that there is no significant difference in the electronic structure between the absorption sites that were considered: center and corner adatom–restatom. Moreover, the different electron occupation of the restatoms and adatoms has a strong effect on the electronic structure of the adsorbed molecule near the Fermi level, and this leads to the reduction of the molecular symmetry to Csor even to C1. In the case of the Si 2p core level, beside the previously reported continuous quenching of the restatom state, we found clear evidence of the existence of a peak corresponding to the Si–C bond separated by 0.44 eV from the bulk component. Furthermore, for the vibrational analysis, isotopic substitution of C2H4with C2D4, gave us more insight into the correct assignment of the modes in the experiment. Specifically, exceptional care must be taken with the allocation of the C–H wagging, twisting, and C–C stretching modes.

Rh nanoparticles of 20–40 nm lateral size were grown on TiO2(110) surface by physical vapor deposition and thermal treatments. The top-facet morphology of the Rh nanoparticles and the particle-free support were characterized by scanning tunneling microscopy. The chemical composition of the surface was checked by Auger electron spectrometry. Although most of the particles exhibited complex overlayers, ordered decoration layers were detected only on the top facet of extended hexagonal Rh particles. Several ordered or quasi-ordered encapsulation phases were detected: (1) a “worm-like” overlayer consisting of 1D stripes (width of 0.5 nm and length of 2–3 nm) oriented in the close-packed crystallographic orientations of the Rh nanoparticles and (2) a “wheel-like” hexagonal structure with unit cell vectors of 1.50 (±0.05) nm. The “worm-like” structure is suggested to be an initial stage in the formation of a “wheel-like” structure. It was proved that it is possible to selectively remove the “wheel-like” decoration phase by Ar+sputtering and to recover it by thermal treatment of a few minutes at 1000 K.