Search results for "Interfaces"
showing 10 items of 1258 documents
Growth of tin oxide thin films composed of nanoparticles on hydrophilic and hydrophobic glass substrates by spray pyrolysis technique
2015
Abstract In this paper, we have demonstrated the growth of tin oxide (SnO 2 ) thin films composed of nanoparticles on hydrophobic (siliconized) and hydrophilic (non-siliconized) glass substrates by using the spray pyrolysis technique. X-ray diffraction (XRD) analysis confirmed the formation of SnO 2 thin films with tetragonal rutile-phase structure. Average particle size of nanoparticles was determined to be in the range of 3–4 nm measured from the front view images obtained by a field emission gun scanning electron microscope (FESEM), while the size of nanoparticle clusters, when present, were in the range of 11–20 nm. Surface morphology of SnO 2 films grown over hydrophobic substrates rev…
Structural and chemical characterization of CdSe-ZnS core-shell quantum dots
2018
Abstract The structural and compositional properties of CdSe-ZnS core-shell quantum dots (QDs) with a sub-nm shell thickness are analyzed at the atomic scale using electron microscopy. QDs with both wurtzite and zinc blende crystal structures, as well as intermixing of the two structures and stacking faults, are observed. High-angle annular dark-field scanning transmission electron microscopy suggests the presence of a lower atomic number epitaxial shell of irregular thickness around a CdSe core. The presence of a shell is confirmed using energy dispersive X-ray spectroscopy. Despite the thickness irregularities, the optical properties of the particles, such as photoluminescence and quantum…
Optical and structural properties of Al 2 O 3 doped ZnO nanotubes prepared by ALD and their photocatalytic application
2018
Abstract Al2O3 doped ZnO nanotubes with controlled ratio of Al2O3 were successfully designed by combining the two techniques of atomic layer deposition (ALD) and electrospinnig. In order to study the effect of Al2O3 doping on optical and structural properties of Al2O3 doped ZnO nanotubes, the prepared samples were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), Fourier-transform infrared (FTIR), reflectance emission and room temperature photoluminescence (PL). The photocatalytic activity and stability of these materials under UV light was studied by the photodegradation of methyl orange (MO). The results indicate that Al2O…
Optical properties of ultrathin Al2O3/ZnO nanolaminates
2015
Abstract Because of their high resistance against ultraviolet and high energy particles, ultrathin amorphous nanolaminates can be very attractive for aerospace application. Here we report on the optical and structural properties of ultrathin Al2O3/ZnO nanolaminates deposited by Atomic Layer Deposition. Structural properties of nanolaminates were studied by GIXRD and AFM. Optical characterization was performed by transmittance, spectroscopic ellipsometry and photoluminescence (PL) spectroscopy. Regression analysis of ellipsometric spectra has shown that absorption peak decreases and blue shifted with the decrease of bilayer thickness in the stack. On the basis of the analysis of structural a…
Green light-emitting devices based on soluble oligo(phenylenevinylenes)
2005
In this work, we report our investigations on the film-forming properties as well as the optical and electroluminescent characterisations of a series of lateral-substituted soluble oligo(phenylenevinylenes) of various conjugation length. Preliminary investigations show that these materials are potential candidates for use in organic light-emitting devices (OLEDs). Two types of OLEDs were fabricated: single layer (SL) and single heterostructure (SHS), with poly(p-phenylenevinylene) (PPV) as hole transporting layer. Our best results were obtained with single layer device emitting green light with a luminance of 0.18 cd m(-2) and 0.24 cd m(-2) at a driving voltage of 10 V. (c) 2004 Elsevier B.…
Visible Photoluminescence of Variable-Length Zinc Oxide Nanorods Embedded in Porous Anodic Alumina Template for Biosensor Applications
2021
Zinc oxide (ZnO) and porous anodic aluminum oxide (PAAO) are technologically important materials, rich with features that are of interest in optical applications, for example, in light-emitting and sensing devices. Here, we present synthesis method of aligned ZnO nanorods (NR) with 40 nm diameter and variable length in 150 to 500 nm range obtained by atomic layer deposition (ALD) of ZnO in pores of continuously variable thickness PAAO. The relative intensity of yellow (1.99 eV), green (2.35 eV), and blue (2.82 eV) photoluminescence (PL) components originating from the different types of defects, varied with non-monotonic dependency on the composite film thickness with a Fabry–Pérot like mod…
Influence of the InAs coverage on the phonon-assisted recombination in InAs/GaAs quantum dots
2002
6 páginas, 3 figuras.
QUADRUPOLAR CHARACTER OF THE Ti K-EDGE PREPEAKS IN TiO2 BY RESONANT AUGER
2002
Resonant spectroscopies offer a new opportunity to get more insight into excited electronic states by studying line shapes and intensities of decay processes. For photon excitations in the pre-K-edge region, the Ti KL 2,3 L 2,3 Auger spectra in TiO 2 show additional peaks when an electron is promoted in localized d-like states via a quadrupolar transition. This resonant process is used to unravel the respective contributions of quadrupolar and dipolar transitions to the absorption edge prepeaks.
Determining the optical properties of adsorbate covered surfaces by dichroism in VUV-photoemission
1999
The dichroic effects of photoemission excited by polarised light depend on the angle of photon incidence. Measurements of the difference in the angle-resolved photoemission intensities from Cs 5p semi-corelevels excited by photons of opposite helicity, or of orthogonal linear polarisation are reported. It was thought that the dependence of dichroism on the angle of incidence cannot be described using equations omitting metal optics. A complete consideration of the vector potential of the exciting light is needed, including the phase shift between it's parallel and perpendicular components. The phase shift is produced by the complex index of refraction. Using the Fresnel equations for struct…
AN EXPERIMENTAL PROOF OF THE BACK-SCATTERING MODEL FOR DICHROIC EFFECTS IN VUV PHOTOEMISSION
2002
The energy dependence of the circular dichroism in the angular distribution of photoelectrons (CDAD) was investigated from the shallow Cs 5p core levels. Cesium was prepared in a hexagonal ordered monolayer on W(110). The results are mainly influenced by scattering of the photoelectrons within the adlayer. At low energies, the behavior observed is described by means of a model that treats only the back-scattering of photoelectrons at the potential step between the adlayer and the substrate. It leads to a simple method determining the position of the monolayer with respect to the substrate. In this approach, the back-scattering model is matched with the measured energy dependence of the CDA…