Nanostructure characterization of carbide-derived carbons by morphological analysis of transmission electron microscopy images combined with physisorption and Raman spectroscopy
ABSTRACTThe interface between ZnSe thin films and GaAs substrates is characterized by High Resolution Transmission Electron Microscopy and room temperature Spectroscopic Ellipsometry. The films were grown on (001) GaAs by Molecular Beam Epitaxy. A three-phase model is used in the reduction of the ellipsometric data, from which the presence of a transition layer of Ga2Se3, with a thickness of less than 1 nm, is confirmed. These results corroborate the high resolution transmission electron microscopy images obtained from the same samples.
ABSTRACTMaterial like PET {polyethylene terephthalate (C10H8O4)n} are usually thrown away present in glasses of refreshments, water bottles between others which are hard to be degraded. However, this material can be recycled and used to acquire nanostructures. During this investigation the objective was to obtain nanoparticles and carbon based nanostructures from the polymer type PET by means of microwave irradiation at the temperature of 260°C at normal pressure and at 600 psi in the presence of acids, ethylene glycol and by means of calcinations. The obtained nanoparticles of ultrananocrystalline diamonds were studied by means of scanning electron microscopy (SEM), high-resolution transmission electron microscopy (TEM), and Raman spectroscopy.
AbstractThe morphology of nanocrystalline (nc)-Si/amorphous (a)-SiO2 superlattices (SLs) is studied using Raman spectroscopy in the acoustic and optical phonon ranges, transmission electron microscopy (TEM), and atomic force microscopy (AFM). It is demonstrated that high temperature annealing (up to 1100°C) and oxidation in O2/H2O ambient do not destroy the SL structure, which retains its original periodicity and nc-Si/a-SiO2 interface abruptness. It is found that oxidation at high temperatures reduces the defect density in nc-Si/a-SiO2 SLs and induces the lateral coalescence of Si nanocrystals (NCs). The size, shape, packing density, and crystallographic orientation of the Si nanocrystals are studied as a function of the oxidation time.
AbstractSamples of chemically-vapor-deposited sub-micrometer-thick films of polysilicon were analyzed by transmission electron microscopy (TEM) in cross-section and by Raman spectroscopy with illumination at their surface. TEM and Raman spectroscopy both find varying amounts of polycrystalline and amorphous silicon in the wafers. Raman spectra obtained using blue, green and red excitation wavelengths to vary the Raman sampling depth are compared with TEM crosssections of these films. Some films have Raman spectra with a band near 497 cm−1, corresponding to numerous nanometer-scale faulted regions in the TEM micrographs.
Abstract
We studied the micrometric morphology and nanometric structure of the celestite (SrSO4) skeleton of acantharian family Acanthometridae. A body of the skeleton composed of 20 radial spines with four blades was characterized using microfocus X-ray computed tomography. The regular arrangement of three types of spines was clarified with the connection of the blades around the root of each spine. The surface of the spines was covered with a chitin-based organic membrane to prevent dissolution in sea water. On the nanometric scale, the mesocrystalline structure that consists of nanoscale grains having a distorted single-crystal nature was revealed using scanning and transmission electron microscopy, electron diffraction, and Raman spectroscopy. The acantharian skeletons have a crystallographically controlled architecture that is covered with a protective organic membrane.
Nanoscale characterization of aircraft soot: A high-resolution transmission electron microscopy, Raman spectroscopy, X-ray photoelectron and near-edge X-ray absorption spectroscopy study
