One challenge in the production of nanometer-sized objects with given properties is to control their growth at a macroscopic scale situ and real time. A dedicated ultrahigh-vacuum grazing-incidence small-angle x-ray scattering setup has been developed, yielding high sensitivity dynamics. Its capabilities derive average particle shape size film mode ordering probe both surfaces buried interfaces are illustrated for two prototypical cases: model catalyst Pd/MgO(100) self-organized Co/Au(111)...

We report the first observation of a large (more than 10%) reflectance anisotropy on Ag(110) single crystal. reproduce experimental data fairly well by use theoretical model, based quasistatic approximation, which takes into account both actual geometry crystal surface and interband intraband transitions. This demonstrates that main effect is screened local-field resonant dipolar oscillation localized near surface.

We present reflectance-anisotropy spectroscopy (RAS) and surface differential reflectivity (SDR) experiments carried out on well-characterized single-domain nominal silicon (100) at room temperature. The results are compared with first-principles calculations which include many-body effects, namely, self-energy excitonic effects. These strongly modify the line shape of optical spectra. For a set five measurements, RAS clean, monohydride, dyhidride surfaces, corresponding SDRs, good agreement...

Substrate effect on the plasmon resonance of flat Ag particles is investigated experimentally, through comparison between a system with substrate amorphous carbon and embedded in carbon. We demonstrate agreement theoretical predictions Bobbert Vlieger, that conventional "spherical" dipole approximation fails to reproduce interaction oblate spheroidal substrate. On contrary, use so-called "spheroidal" yields very good experiment, leading only slight red-shift resonance. Moreover, we show...

Using scanning tunneling microscopy (STM), the elaboration of so-called silicene layer on Ag(111) is monitored in real time during Si evaporation at different temperatures. It shown that growth accompanied by release about 65% surface Ag atoms from covered areas. We observe islands develop terraces and strips step edges, progressively forming ordered (4×4), (13×13) R13.9°, dotted phases. Meanwhile, displaced group to additional bare growing round pristine edges. This indicates a strong...

We report here in situ measurements of the evolution Ag(110) surface during Si growth, using scanning tunneling microscopy and grazing incidence x-ray diffraction. provide compelling evidence an reconstruction associated with release Ag atoms induced by growth nanoribbons. Our results are agreement a missing row layer underneath This challenges current understanding on nonreconstructed Ag(110), interpreted within framework silicene models.

The highly oriented pyrolytic graphite (HOPG) surface, consisting of a dangling bond-free lattice, is regarded as potential substrate for van der Waals heteroepitaxy two-dimensional layered materials. In this work, the growth silicon and germanium on HOPG investigated with scanning tunneling microscopy by using typical synthesis conditions silicene germanene metal surfaces. At low coverages, deposition Si Ge gives rise to tiny sparse clusters that are surrounded honeycomb superstructure....

Silver is a popular choice of substrate for the growth nanostructured 1D and 2D silicon -- possibly silicenelike layers. First-principles simulations measurements reflectance anisotropy surface differential reflectivity spectroscopy are applied to study single monolayer Si/Ag(111) Si/Ag(110) interfaces. The authors demonstrate absence structural electronic properties freestanding, graphenelike silicene, finding evidence strong Si-Ag bonding in case formation pentagonal nanoribbons on...

The combination of in situ real-time surface differential reflectivity (SDR) spectroscopy and microscopic calculations has been used for the first time to investigate gas adsorption on a Si surface. optical signatures some structural units Si(111)-( $7\ifmmode\times\else\texttimes\fi{}7$) have identified. development corresponding features SDR spectra upon amount H exposure allowed us demonstrate occurrence two different mechanisms hydrogenation determine their relative kinetics.

This paper compares the capability of surface differential reflectivity spectroscopy (SDRS) and grazing incidence small angle x-ray scattering (GISAXS) to characterize in situ, ``at a glance,'' collection nanoclusters by statistically defining geometry an average particle (diameter, height, interparticle distance). SDRS GISAXS are run simultaneously on Ag/MgO(001) films during their growth. They shown lead consistent values morphological parameters, with particular good agreement about...

Scanning tunneling microscopy has been used to real-time study the growth of silicene on $\mathrm{Ag}(111)$ in 200--533-K temperature range. We show that mode depends strongly deposition $T$. At $T=300\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ and above, formation results from exchange between surface Ag atoms Si atoms, which are inserted substrate top layer. Density functional theory calculations confirm insertion is thermodynamically favored, we propose an energetic model for explaining...

We show that the study of gold nanoparticle self-assemblies induced by a liquid crystal matrix reveals intimate distorted structure existing prior to nanoparticles' incorporation. also how this controls spacing between nanoparticles in self-assemblies. have created hybrid films cholesteric (CLC) and nanoparticles, CLC being deformed competing anchorings at its two interfaces. Whereas previous results evidenced formation only slightly anisotropic clusters for large (diameter 20 nm), we now...

The structure of silicene multilayers grown on $\mathrm{Ag}(111)$ and the nature their $\sqrt{3}\phantom{\rule{0.16em}{0ex}}\ifmmode\times\else\texttimes\fi{}\phantom{\rule{0.16em}{0ex}}\sqrt{3}\phantom{\rule{0.16em}{0ex}}R{30}^{\ensuremath{\circ}}\phantom{\rule{0.16em}{0ex}}$ reconstruction were studied by low-energy electron diffraction, Auger spectroscopy, optical reflectance methods. It is shown that surface induced a surfactant layer silver atoms during growth silicon film not due to...

Two-dimensional (2D) honeycomb lattices beyond graphene, such as germanene, appear very promising due to their outstanding electronic properties, the quantum spin Hall effects. While there have been many claims of germanene monolayers up now, no experimental evidence a structure has provided now for these grown monolayers. Using scanning tunneling microscopy (STM), surface X-ray diffraction (SXRD), and density functional theory, we elucidated Ge-induced (109×109)R±24.5° reconstruction on...

Differential reflectivity $\frac{\ensuremath{\Delta}R}{R}$ measurements between a smooth Ag surface and the same covered by silver deposits of various thicknesses were performed in ultrahigh vacuum over (1.5-5)-eV spectral range for different substrate temperatures. One monolayer on at 125 K gives rise to relatively large changes (~ ${10}^{\ensuremath{-}3}$). For thicker (four monolayers or more) well-defined absorption 3.5 eV due surface-plasmon excitation is found. The experimental results...

Diffuse optical reflectance of Au/TiO2 powder catalysts, prepared by the deposition−precipitation method, is measured in UV−visible range controlled atmosphere. An intense absorption observed around 550 nm interpreted excitation plasmon resonances 4 gold nanoparticles (NPs). The location, intensity, and width can be reproduced theoretically using a distribution shapes NPs. changes upon exposure catalyst to different atmospheres (O2/He, H2/He, CO/He) are real-time use homemade differential...

We investigated composite films of gold nanoparticles (NPs)/liquid crystal (LC) defects as a model system to understand the key parameters, which allow for an accurate control NP anisotropic self-assemblies using soft templates. combined spectrophotometry, Raman spectroscopy, and grazing incidence small-angle X-ray scattering with calculations dipole coupling models sphere interactions. demonstrate that dense arrays elementary edge dislocations can strongly localize small NPs along defect...

From grazing-incidence x-ray diffraction measurements and density functional theory calculations, we have precisely determined the atomic positions of Si Ag atoms forming $(4\ifmmode\times\else\texttimes\fi{}4)$ Si/Ag(111) silicene reconstruction. A remarkable agreement is found between experimental structure factors theoretical ones derived from calculations. Our results confirm honeycomb previously proposed, with a buckling equal to 0.77 \AA{}. The substrate are also relaxed, leading...

Missing-row reconstructions on Au(110) immersed in electrolytes have been studied by situ reflectance anisotropy spectroscopy. Transitions between the 1 x 3, 2, and surface structures were monitored as a function of applied potential. A kinetic model allowed us to reproduce data satisfactorily. These results confirm theoretical predictions showing that charge determines reconstruction. The transition potentials activation barriers determined.

Surface reflectance spectroscopy performed on an alumina surface covered by silver particles shows a blue shift of the dipolar plasma resonance in very small spheres. Theoretical calculations which take into account surface-diffuseness effect or quantum-size reproduce experimental shift.

The adsorption of atoms and molecules several gases the Si(100)2x1 silicon reconstructed surface is investigated by differential reflectance spectroscopy. This UV-visible optical spectroscopy makes possible discrimination between two modes, depending on whether or not leads to breaking Si-Si dimers. observation different features assigned bonding dangling bonds dimers, gives access mode hydrogen, water, oxygen, pyridine. Moreover, technique being quantitative, we can determine total amount...

We provide a comprehensive investigation of the adsorption tertiary amine molecule, triethylamine (TEA, N(CH2CH3)3), on Si(001)-(2 × 1) surface at room temperature (RT), using real-time synchrotron radiation X-ray photoemission (XPS) and scanning tunneling microscopy (STM), in combination with density functional theory (DFT) calculations. Real-time XPS measurements point to two consecutive reactions, first one leading formation dative adduct, second conversion latter into dissociated adduct...

The optical properties of Si nanoribbons grown on Ag(110) under ultrahigh vacuum have been experimentally determined by use in situ surface differential reflectance spectroscopy. Real-time measurements showed a clear transition the response deposit at full coverage surface, corresponding to 0.8 monolayer silicon. spectra measured for complete self-assembled nanoribbon layer are different from spectrum calculated silicene silver, which rules out possible silicenelike character this layer....