We present calorimetric measurements of the effect cluster size on adsorption enthalpy carbon monoxide Pd nanoclusters sized from 120 to 4900 atoms per particle, which were grown in situ a well-ordered ${\text{Fe}}_{3}{\text{O}}_{4}/\text{Pt}(111)$ film. A substantial decrease initial heat amounting about $20--40\text{ }\text{kJ}\text{ }{\text{mol}}^{\ensuremath{-}1}$ was observed smallest nanoparticles as compared larger clusters and extended Pd(111) single-crystal surface. discuss this...

A new ultrahigh vacuum microcalorimeter for measuring heats of adsorption and adsorption-induced surface reactions on complex single crystal-based model surfaces is described. It has been specifically designed to study the interaction gaseous molecules with well-defined catalysts consisting metal nanoparticles supported crystal or epitaxial thin oxide films grown crystals. The detection principle based previously described measurement temperature rise upon by use a pyroelectric polymer...

The heat of adsorption and sticking probability CO on well-defined Pd nanoparticles were measured as a function particle size using single crystal microcalorimetry. particles different average sizes ranging from 120 to 4900 atoms per (or 1.8 8 nm) Pd(111) used that supported model in situ grown Fe(3)O(4)/Pt(111) oxide film. To precisely quantify the energies, reflectivities investigated surfaces thickness Fe(3)O(4) layer amount deposited Pd. A substantial decrease binding energy was found...

Abstract We present a spectroscopic ellipsometry study of Mo-doped VO 2 thin films deposited on silicon substrates for the mid-infrared range. The dielectric functions and conductivity were extracted from analytical fittings Ψ Δ ellipsometric angles showing strong dependence dopant concentration temperature. Insulator-to-metal transition (IMT) temperature is found to decrease linearly with increasing doping level. A correction classical Drude model (termed Drude-Smith) has been shown provide...

We present a new type of reflectance difference (RD) spectrometer for fast spectroscopic measurements based on rotating-compensator (RC) design. The instrument uses 1024 element Si photodiode linear array simultaneous multiwavelength detection. High quality RD spectra covering spectral range from 1.5 to 4.5 eV can be acquired within few seconds. A detailed description the working principle, instrumentation, and algorithms used data collection reduction is presented, followed by discussion...

Dedoping of PEDOT:PSS by a simple and physical process has been performed the addition 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), strong organic base, in aqueous dispersion. The DBU-treated samples showed absorption band at 600 nm (π–π* transition) small 900 (polaronic band), which indicates that some PEDOT chains were being reduced. dedoping efficiency depended amount DBU added to dispersions films yellow emission, visible with naked eye, when they excited 488 laser. In addition, same...

We report on the optical properties of Ag nanoparticles supported an insulating, birefringent substrate for nominal film thicknesses less than 4 nm. Spectroscopic ellipsometry (SE) and reflectance-difference spectroscopy (RDS) were employed to detect out-of-plane in-plane anisotropies particle-plasmon resonances, respectively. Quantitative agreement between measured calculated spectra is achieved using morphological parameters determined independently from electron microscopy images. The...

We report measurements of reflectance difference (RD) spectra for $c(4\ifmmode\times\else\texttimes\fi{}4)$ and $(2\ifmmode\times\else\texttimes\fi{}4)$ reconstructed (001) surfaces GaAs. Surface dimers induce an inhomogeneous orthorhombic strain field that penetrates several monolayers into the crystal. The thickness $d$ this strained region is smaller than penetration depth $L$ probing light, anisotropy formalism can be used. dielectric function GaAs at room temperature described by a...

We report photoreflectance-difference and reflectance-difference measurements on reconstructed GaAs (001) surfaces. From these data the linear quadratic electro-optic coefficient spectra are determined in important 2.8-3.4 eV spectral region. The surface strain fields induced by reconstruction also determined. show experimentally that between c(4x4) (2x4) surfaces, there is an inversion of electric field which we attribute to a direct piezo-electric effect related reconstruction.

We report on reflectance-difference spectra of $n$-type $\mathrm{GaAs}$$(001)$ under a $[110]$ uniaxial stress. Measurements where carried out in the energy range from $2.5\ensuremath{-}5.5\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$. This comprises transitions ${E}_{1}$, ${E}_{1}+{\ensuremath{\Delta}}_{1}$, ${E}_{0}^{\ensuremath{'}}$, ${E}_{0}^{\ensuremath{'}}+{\ensuremath{\Delta}}_{0}^{\ensuremath{'}}$,...

The growth and concomitant evolution of the optical properties Ag nano-clusters deposited on biaxially extruded poly(ethylene terephthalate) films is studied by reflectance difference spectroscopy. It demonstrated low energy ion scattering simulated spectra that clusters form a two-dimensional layer buried beneath surface substrate. experimental are described simulations in which different configurations host such as anisotropy, amorphization, dilution considered an effective medium...

The wavelength dependence of the retardation induced by a photoelastic modulator (PEM) is central issue in multichannel modulator-based spectroscopic ellipsometry and reflectance difference spectroscopy (RDS), where optical signal detected simultaneously at different wavelengths. Here we present refined analysis crystal's its effect on quality. Two correction schemes that take into account actual stress-optic coefficient are introduced. It demonstrated experimentally both methods provide...

Abstract Reflectance difference spectroscopy (RDS/RAS) constitutes a very sensitive tool for the study of optical properties semiconductors. RDS spectra comprise several components different physical origins. One these is strain induced by surface. In present work, we report RD measured on GaAs at room temperature around E 1 and + Δ transitions. Two cases were studied, surface strains c (4 × 4) reconstruction vacancies generated annealing semi insulating crystal. Fits to line shape...

AbstractAbstractIn this work, a methodology is proposed to identify the components used in historic photographs using non-invasive and non-destructive characterisation techniques. The provides an approach for analysing by following three steps represented flowchart: firstly, type of binder determined identifying morphological structural characteristics; secondly, presence or absence baryta layer established; finally, organic as part protective determined. characteristics properties revealed...

Abstract We report on the optical characterization of non-magnetic metal (NM)/ferromagnetic (Co 20 Fe 60 B )/MgO heterostructures and interfaces by using mid infrared (MIR) spectroscopic ellipsometry at room temperature. extracted for MIR range dielectric function (DF) Co , that is lacking in literature, from a multisample analysis. From modeling we detected determined tensor properties two-dimensional electron gas (2DEG) forming NM CoFeB interface. These comprise independent Drude...

Abstract Reflectance Difference (RD/RAS) spectroscopy has emerged in the last two decades as a sensitive probe for study of surface and surface‐induced phenomena zincblende semiconductors. This measures difference reflectivity between mutually orthogonal polarizations it is thus specific to semiconductor regions with symmetries lower than cubic. Photoreflectance‐difference (PRD) technique closely related RD that photoreflectance spectra, one linearly‐polarized light other non‐polarized...

Reflectance difference spectroscopy has been applied for the in-situ characterization of growth Ag cluster films on insulating birefringent Al2O3 $(10\overline{1}0)$ substrates in spectral range 1.5–5 eV. Information individual cluster, film morphology and are derived from anisotropy in-plane plasmon resonances comparison with scanning electron microscopy images. In particular, evolution dipolar resonance attributed to two distinct stages coarsening involving particle aggregation ripening,...

Spectroscopic ellipsometry (SE) has been utilized during the past decades for measurement of dielectric function semiconductors. By using SE, interband critical point parameters such as energy gaps and broadenings are routinely determined. In direct-space analysis approach, these known by taking numerical derivatives fitting spectra a Lorenzian line shape. However, in many cases noise does not allow determination precisely they needed. Additionally, character transitions, which is...

We have used reflectance difference spectroscopy (RDS) and its extension, azimuth-dependent RDS (ADRDS), to study the properties of sputtered evaporated nickel films on biaxially oriented poly(ethylene terephtalate) (PET) in a roll web-coating process. From full set ADRDS spectra we extract analyze both intrinsic azimuthal orientation effective optical anisotropy samples. latter, contributions arising from layer PET substrate with different orientations eigenaxes can be inferred. find an...

Focusing on the photographic archive of Julian Carrillo (Mexico), we study and characterize processes a set 13 photographs dated between 1884 1925. By using infrared spectroscopic ellipsometry, classified selected according to its kind binder. Thus, recognized for each photograph, presence proteins, therefore, particular process. Furthermore, have identified baryta layer, use plasticizer, eventual coating utilized protect whose composition was based in natural organic components, mainly...

We present a model to describe the Reflectance-difference (RD) spectra of InGaAs grown on GaAs (001) at T = 500 °C, in energy range from 2.3–3.5 eV. The assumes presence an orthorhombic strain epilayer that accounts for anisotropic process nucleation islands. show developed leads accurate fits experimental RD InGaAs/GaAs thickness both below and above critical 2D-3D growth-mode transition. From fitting theoretical line shapes we obtain quantitative information changes surface stoichiometry...