We present a combined study by scanning tunneling microscopy and atomistic simulations of the emission of dissociated dislocation loops by nanoindentation on a (001) fcc surface. The latter consist of two stacking-fault ribbons bounded by Shockley partials and a stair-rod dislocation. These dissociated loops, which intersect the surface, are shown to originate from loops of interstitial character emitted along the <110> directions and are usually located at hundreds of angstroms away from the indentation point. Simulations reproduce the nucleation and glide of these dislocation loops.

Methanol decomposition and oxidation on Pd(111) at millibar pressure were studied by in situ polarization-modulation infrared reflection absorption spectroscopy (PM-IRAS), on-line gas chromatography and pre- and postreaction X-ray photoelectron spectroscopy (XPS). Various dehydrogenation products such as methoxy CH3O, formaldehyde CH2O, formyl CHO, and CO could be spectroscopically identified. Methanol oxidation proceeds via dehydrogenation to formaldehyde CH2O, which either desorbs or is further dehydrogenated to CO, which is subsequently oxidized to CO2. Carbonaceous overlayers that are present during the reaction may favorably affect the selectivity toward CH2O. The reaction takes place on metallic Pd, and no indications of an involvement of Pd surface oxide were observed.

We present here a study on the surface plasmon resonance (SPR) in Au films deposited onto glass substrates and annealed in air at different temperatures. The initial Au films exhibit the resonant absorption of extended surface plasmons which depends on the film thickness. Thermal treatments promote the modification of the continuous films toward the formation of Au isolated islands. The morphological features of the islands depend on the film initial thickness and annealing temperature. The optical properties of the films are qualitatively modified as a consequence of the morphological changes. For films with initial thickness below 30 nm, the islands exhibit localized SPR while thicker films lead to islands large enough to hold extended SPR.

The oldest known magnetic material, magnetite, is of current interest for use in spintronics as a thin film. An open question is how thin can magnetite films be and still retain the robust ferrimagnetism required for many applications. We have grown 1-nm-thick magnetite crystals and characterized them in situ by electron and photoelectron microscopies including selected-area x-ray circular dichroism. Well-defined magnetic patterns are observed in individual nanocrystals up to at least 520 K, establishing the retention of ferrimagnetism in magnetite two unit cells thick.

In this work, we present a sol–gel synthesis of ε-Fe2O3 nano and microparticles stabilized in silica thin films. Thanks to the relatively high size of the synthesized particles, we have been able to discriminate the Raman signal of the ε- and α-Fe2O3 phases, thus presenting the first Confocal Raman Microscopy study of isolated ε-Fe2O3 particles. The vibrational modes of each phase are identified at room temperature. The phase transition from ε- to α-Fe2O3 and the morphological modifications are analyzed as a function of the in situ output laser power. A complete study of the Raman spectra for ε-Fe2O3 particles has been performed for a wide range of temperatures (80–570 K). The phonon frequencies and line widths show a behavior in which the contributions from lattice thermal expansion and anharmonic interactions have to be considered. We have also identified a two-magnon mode in the ε-Fe2O3 phase. Its intensity increases close to the Néel transition (TN) and persists well above it. This observation could be one of the few experimental examples of a paramagnon, i.e., a magnetic excitation in a paramagnetic state.