Search results for "high-resolution transmission electron microscopy"
showing 10 items of 102 documents
Facile synthesis and characterization of functionalized, monocrystalline rutile TiO2 nanorods.
2006
Functionalized, monocrystalline rutile TiO2 nanorods were prepared from TiCl4 in aqueous solution under acidic conditions in the presence of dopamine, followed by aging and hydrothermal treatment at 150 degrees C. The surface-bound organic ligand controls the morphology as well as the crystallinity and the phase selection of TiO2. The presence of monocrystalline rutile TiO2 was confirmed by X-ray powder diffraction and HRTEM investigations. The as-prepared nanorods are soluble in water at pH3. The surface functionalization was analyzed by IR and 1H NMR, confirming the presence of dopamine on the surface. The surface amine groups can be tailored further with functional molecules such as dyes…
Diamond nucleation on iridium: local variations of structure and density within the BEN layer
2009
Abstract The diamond nuclei generated by the bias enhanced nucleation (BEN) on iridium are gathered in well defined areas (“domains”). In atomic force microscopy (AFM) measurements they become manifest in a 1 nm downward step. The fine structure of the carbon layer inside and outside these domains has been studied by small spot Auger electron spectroscopy (AES), high resolution transmission electron microscopy (HRTEM), AFM and lateral force microscopy (LFM). The Auger spectra of the carbon KLL peak taken in an ultra high vacuum setup revealed diamond features inside and more graphitic features outside the domains. The comparison with the intensity of the Auger signal originating from the un…
Tuning the size and shape of nano-boehmites by a free-additive hydrothermal method
2015
A synthetic procedure allowing the control of boehmite micro and nanoparticles is presented. The proposed hydrothermal synthetic procedure is based on the control of three reaction parameters, the pH and temperature of precipitation of xerogels and the water/xerogel ratio for the hydrothermal process, carried out at 200 °C for 48 h. Results obtained by measurements on transmission electron microscopy (TEM) images indicate that at pH 5 micro or nanorods of controlled length between ca. 300 and 50 nm were obtained depending on the temperature of precipitation of the xerogel (25 or 100 °C) and the water/xerogel ratio used (1/1, 6/1, 15/1). On the contrary, at pH 10, nanoplatelets with major ba…
Atomic structure solution of the complex quasicrystal approximant Al77Rh15Ru8 from electron diffraction data
2014
The crystal structure of the novel Al77Rh15Ru8phase (which is an approximant of decagonal quasicrystals) was determined using modern direct methods (MDM) applied to automated electron diffraction tomography (ADT) data. The Al77Rh15Ru8E-phase is orthorhombic [Pbma,a= 23.40 (5),b= 16.20 (4) andc= 20.00 (5) Å] and has one of the most complicated intermetallic structures solved solely by electron diffraction methods. Its structural model consists of 78 unique atomic positions in the unit cell (19 Rh/Ru and 59 Al). Precession electron diffraction (PED) patterns and high-resolution electron microscopy (HRTEM) images were used for the validation of the proposed atomic model. The structure of the E…
"Sweet Chemistry": a Green Way for Obtaining Selenium Nanoparticles Active against Cancer Cells
2017
We present an environment friendly synthesis of selenium nanoparticles and the study of their cytotoxic activity against uterine sarcoma cancer and fibroblasts cells. Amorphous selenium (a-SeNPs) and trigonal selenium (t-SeNPs) were synthesized using D-fructose as the reducing agent and characterized by high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDX), powder X-ray diffraction analysis (XRD), inductively coupled plasma optical emission spectrometry (ICP OES), dynamic light scattering (DLS) to obtain zeta potential values and cyclic voltammetry (CV). Particularly, a-SeNPs presented high toxicity toward the resistant cancer cell line MES-SA/…
A Scanning Electron Microscope for Ultracold Atoms
2006
We propose a new technique for the detection of single atoms in ultracold quantum gases. The technique is based on scanning electron microscopy and employs the electron impact ionization of trapped atoms with a focussed electron probe. Subsequent detection of the resulting ions allows for the reconstruction of the atoms position. This technique is expected to achieve a much better spatial resolution compared to any optical detection method. In combination with the sensitivity to single atoms, it makes new in situ measurements of atomic correlations possible. The detection principle is also well suited for the addressing of individual sites in optical lattices.
Dopant Contrast in Semiconductors as Interpretation Challenge at Imaging by Electrons
2007
Mechanisms responsible for the contrast between differently doped areas in semiconductors, which is observed in electron micrographs, is discussed as regards the key factors determining the sign and magnitude of the contrast. Experimental data obtained by means of the scanning electron microscope (SEM), scanning low energy electron microscope and photoelectron emission microscope are reviewed together with hints following from them for compilation of a model of the contrast mechanism.
Growth and defect studies of CdTe particles
2013
The paper reports the epitaxial growth of cadmium telluride (CdTe) particles by thermal deposition on cleaved planes of (001)NaCl and (001)KBr. Using high resolution transmission electron microscopy and electron diffraction it was shown that CdTe particles could have different orientation and phase (cubic or hexagonal) depending on the substrate temperature. Their most common defects are twins and stacking faults.
Structure and Deformations of Pd−Ni Core−Shell Nanoparticles
2005
International audience; Homogeneous collections of Pd−Ni core−shell nanoparticles have been prepared by decomposition of metal−organic compounds and studied by several electron microscopy techniques: transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), high-resolution transmission electron microscopy (HRTEM), energy-filtered microscopy (EFTEM), and by X-ray photoelectron spectroscopy (XPS). The physical and chemical properties of the Pd shell are supposed to depend on its electronic properties, which are influenced by the presence of the Ni core and by the deformation in the Pd lattice. Here, the interfacial structure of Pd/Ni and the lattice deformations in t…
Structural properties of GaN quantum dots
2006
The strain state and the deformation profile of GaN quantum dots embedded in AlN have been measured by high resolution electron microscopy, medium energy ion scattering and grazing incidence X-ray diffraction. The results are compared with theoretical calculations, allowing one to conclude that GaN quantum dots experience a non biaxial strain which drastically decreases when going from the basal plane up to the apex of the dots. We also demonstrate that AlN is distorted in the surroundings of the dots, which provides the driving force for vertical correlation of GaN dots when the AlN spacer between successive planes is thin enough.