Search results for "interfaces"
showing 10 items of 1258 documents
Ellipsometric thickness and coverage of physisorbed layers of Xe, Kr, Ar and N2 on graphite
1990
Multilayer isotherms of Xe, Kr, Ar and N2 physisorbed on graphite (001) have been studied by ellipsometry. It is shown that the model of Dignam and Fedyk provides an excellent basis for the interpretation of the ellipsometric thickness in terms of the coverage and the polarizability of the admolecules. For N2 conclusions concerning the orientation of the molecule are drawn.
Superficial defects induced by argon and oxygen bombardments on (110) TiO2 surfaces
1998
Abstract Compositional and chemical changes of titanium dioxide monocrystalline surfaces induced by bombardment with 4 keV argon and oxygen ions have been studied by AES, XPS and AFM. Argon ion bombardment induced strong changes in the composition and chemical state of the surface: loss of oxygen due to preferential sputtering occurred, and, related to this, Ti4+ species were reduced to Ti3+ and Ti2+. During oxygen bombardment, competition between preferential sputtering of oxygen ions of the oxide surface and oxygen implantation was observed. This phenomenon was found to be strongly dependent upon the incidence angle of the oxygen ions. Moreover, an oxygen bombardment with normal incidence…
Interannual variability of Greenland winter precipitation sources: 2. Effects of North Atlantic Oscillation variability on stable isotopes in precipi…
2008
[1] A new Lagrangian moisture source diagnostic is applied to identify the atmospheric conditions relevant for the fractionation of stable water isotopes during evaporation over the ocean and subsequent transport to Greenland. Northern Hemisphere winter months with positive and negative North Atlantic Oscillation (NAO) index are studied on the basis of ERA-40 reanalysis data. Diagnosed moisture transport conditions are supplied to a Rayleigh-type isotope fractionation model to derive estimates for the isotopic composition of stable isotopes in winter precipitation on the Greenland plateau for the two NAO phases. Because of changes in atmospheric circulation, moisture source locations for pr…
Particle size distributions of currently used pesticides in a rural atmosphere of France
2013
This work presents first data on the particle size distributions of current-used pesticides in the atmosphere. Ambient air samples were collected using a cascade impactor distributed into four size fractions in a rural site of Centre Region (France). Most pesticides were accumulated in the fine (0.1-1 mu m) particle size fraction such as cyprodinil, pendimethalin, fenpropidin, fenpropimorph and spiroxamine. Other pesticides such as acetochlor and metolachlor presented a bimodal distribution with maximum concentrations in the ultrafine (0.03-0.1 mu m) coarse (1-10 mu m) and in the ultrafine fine size ranges, respectively. No pesticides were detected in the size fraction >10 mu m. (C) 2013 El…
Vegetation fire emissions and their impact on air pollution and climate
2009
Gaseous and particulate emissions from vegetation fires substantially modify the atmospheric chemical composition, degrade air quality and can alter weather and climate. The impact of vegetation fire emissions on air pollution and climate has been recognised in the late 1970s. The application of satellite data for fire-related studies in the beginning of the 21th century represented a major break through in our understanding of the global importance of fires. Today the location and extent of vegetation fires, burned area and emissions released from fires are determined from satellite products even though many uncertainties persist. Numerous dedicated experimental and modeling studies contri…
Discotic Twin and Triple Molecules with Charge-Transfer Interactions in Langmuir−Blodgett Films
1996
X-ray and atomic force microscopy observations reveal features of the surface morphology of Langmuir-Blodgett (LB) films from discotic donor-acceptor molecules with strong core-to-core interactions caused by a charge-transfer (CT) complexation. The compounds are designed to be twin and triple molecules composed of chemically connected donor (triphenylene) and acceptor (trinitrofluorenone) fragments which display liquid crystalline structure in the bulk state. The LB films from these compounds possess edge-on orientation of molecules within monolayers with a smooth surface on a submicron scale but with substantial macroscopic imperfections. These imperfections are represented by the micron s…
Dissociative adsorption of water on Au/MgO/Ag(001) from first principles calculations
2015
Abstract The molecular and dissociative adsorption of water on a Ag-supported 1 ML, 2 ML and 3 ML-a six atomic layer-thick MgO films with a single Au adatom is investigated using density functional theory calculations. The obtained results are compared to a bulk MgO(001) surface with an Au atom. On thin films the negatively charged Au strengthens the binding of the polar water molecule due to the attractive Au–H interaction. The adsorption energy trends of OH and H with respect to the film thickness depend on an adsorption site. In the case OH or H binds atop Au on MgO/Ag(001), the adsorption becomes more exothermic with the increasing film thickness, while the reverse trend is seen when th…
Dance to your own drum: Identification of musical genre and individual dancer from motion capture using machine learning
2020
Machine learning has been used to accurately classify musical genre using features derived from audio signals. Musical genre, as well as lower-level audio features of music, have also been shown to...
Surface spectroscopic study of the corrosion of ultrathin57Fe-evaporated and Langmuir-Blodgett films in humid SO2 environments
2000
Integral conversion electron Mossbauer spectroscopy (ICEMS), x-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and scanning electron microscopy (SEM) have been used to carry out a comparative study of the corrosion resistance against humid SO2-aggressive environments of ultrathin 57Fe films. These films, having a thickness ≤ 2.5 nm, have been prepared by evaporation of 57Fe under vacuum and by 57Fe coating by a Langmuir–Blodgett (LB) technique on SiO2/Si wafers. The results have shown that the corrosion resistance of the evaporated films is similar to that of massive Fe. However, the LB films show a remarkably higher corrosion resistance. Thus, although the Fe films …
Iron deposition on TiO2(110): effect of the surface stoichiometry and roughness
1999
Abstract Characterizations of ultra-thin iron films deposited on TiO 2 (110) surfaces with different stoichiometries, roughnesses and crystallinities have been carried out by X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). For a high initial roughness of the substrate, a 2D growth mode is observed up to three monolayers. But, if the initial roughness is low, clusters grow on the TiO 2 surface. Whatever the initial surface stoichiometry, electronic exchanges occur between titanium and iron leading to a reduction of titanium and an oxidation of iron. This interaction between iron and titanium dioxide surface takes place only at the interface between the metal and…