Search results for "Surfaces"
showing 10 items of 2837 documents
Al2O3 ALD films grown using TMA + rare isotope 2H216O and 1H218O precursors
2021
Abstract In this work hydrogen and oxygen migration and exchange reactions in the atomic layer deposited (ALD) Al2O3 thin films were studied together with hydrogen incorporation by varying deposition parameters. Al2O3 films deposited at low temperatures can contain more than 20 at.% of hydrogen. Both higher temperature and longer purge length decrease the hydrogen and carbon concentrations significantly. In order to track the hydrogen and oxygen movement in the films, heavy water (2 H 2 16 O) and oxygen-18 enriched water (1 H 2 18 O) were used as precursors in combination with trimethylaluminium (TMA). Different isotopes of the same element were quantified by means of time-of-flight elastic…
Small Gold Nanoparticles Synthesized with Sodium Citrate and Heavy Water: Insights into the Reaction Mechanism
2010
5 páginas, 3 figuras, 1 esquema.
Water structure in water/AOT/n-heptane microemulsions by FT-IR spectroscopy
1992
Abstract FT-IR spectra in the OH stretching region of water/sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/n-heptane microemulsions as a function of the water/AOT molar ratio (R) and of the weight fraction (φ) of the micellar phase have been recorded at 25°C. After elimination of the unwanted CH contribution and correction for the water concentration, the shape of the normalized OH bands has been found to be dependent on R and practically independent of φ. The analysis of these bands in terms of “bound” and “bulk” water (representing, as a first approximation, the two water domains within the water pool) allowed the evaluation of the fraction (α) of the “bound” water as a function of R. A…
Investigation of surface properties of lunar regolith: Part I
2007
This paper describes an initial investigation of the surface properties of three lunar soil samples from the Apollo 11, 12 and 16 missions, respectively. We report on density measurements using a helium pycnometer, adsorption isotherms of krypton applied for the determination of specific surface area of the samples and gravimetric measurement of the isotherms of water, heptane and octane. Electron-microscopic photographs are described and discussed.
Synthesis and characterization of CdS nanoparticles embedded in a polymethylmethacrylate matrix
2005
CdS nanopowder capped with sodium bis(2-ethylhexyl)sulfosuccinate was synthesized by using water-in-oil microemulsions. The CdS nanoparticles of about 5 nm obtained were embedded in polymethylmethacrylate matrix by a photocuring process. The transparent yellow solid compound was characterized by optical absorption and emission spectroscopy, high-resolution transmission electron microscopy, and energy-dispersive X-ray spectroscopy. The properties of this compound were compared with those of the nanopowder dispersed in heptane and in methylmethacrylate. The results obtained indicate that the nanoparticles are homogeneously dispersed in the matrix and do not change in size during the embedding…
Heptane Adsorption in Silicalite-1: Neutron Scattering Investigation
2007
International audience; Structural properties of confined deuterated n-heptane in silicalite-1 have been investigated by neutron scattering experiments during the adsorption process. At 300 K, the adsorption isotherm shows a sharp inflection at a loading near Nads ) 4 molecules per silicalite-1 unit cell. In addition, the diffusivities obtained from recent QENS data exhibit a loading dependence. Our motivation is to find structural signatures of the peculiar behavior of n-heptane in silicalite-1 and to check the numerous computer simulation findings of this behavior. Our detailed neutron diffraction investigation agrees with the MONO-ORTHO phase transition of the silicalite-1 above a Nads v…
Laser heterodyne displacement measuring using PLZT frequency shifter
1991
Abstract The implementation of a frequency shifter based on lead lanthanum zirconate titanate ceramic (PLZT) and a voltage-controlled λ/4 plate is described. The capabilities of these elements are demonstrated with results from a Michelson-type laser heterodyne displacement measuring interferometer with 0.01 μm accuracy and 1 Hz display update rate.
Mo(CO)6 dissociation on Cu(111) stimulated by a Scanning Tunneling Microscope
2013
Abstract The surface of Cu(111) was exposed to molybdenum hexacarbonyl Mo(CO)6 with monolayer coverage at temperature 160 K and studied by a Scanning Tunneling Microscope. The monolayer structure has a hexagonal arrangement and forms a (√7 × √7) R19 superlattice on the copper (111) plane. Upon repeated scanning the monolayer is transformed into a (1 × 2) superstructure with 3-fold oriented domains. The domains of (1 × 2) superstructure can change orientation under scanning according to 3-fold surface symmetry. From analysis of the domain mobility, it follows that CO groups of carbonyl fragments are organized in the (1 × 2) superstructure conditioning the domain reorientation. The observed s…
Atmospheric pressure plasma polymerisation of metalloporphyrins containing mesoporous membranes for gas sensing applications
2013
Abstract Metalloporphyrins are embedded in an organosilicon matrix by an easily up-scalable atmospheric pressure dielectric barrier discharge method. The integrity of the metalloporphyrins, followed by UV–visible spectroscopy, is successfully preserved and their aggregation prevented. The single molecule properties, rather than the bulk ones, are thus enhanced. Exposure to triethylamine, which reaches the metalloporphyrins through the pores of the organosilicon membrane, led to a shift in the absorption spectrum and confirms the gas sensing potential of such coatings.
Electrochemical formation of N,N′-diarylhydrazines by dehydrogenative N–N homocoupling reaction
2020
Hydrazines represent a class of compounds of high interest due to their applicability as versatile starting materials in many important transformations. Herein, we report a synthetic approach to hydrazine derivatives using commercially available anilines and an anodic dehydrogenative N-N coupling reaction as the key step.