Search results for "Electron microscope"
showing 10 items of 784 documents
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…
Synthesis of novel ZnO/ZnAl2O4 multi co-centric nanotubes and their long-term stability in photocatalytic application
2016
Based on the Kirkendall effect, novel double, triple and quadruple co-centric nanotubes of ZnO/ZnAl2O4 have been successfully fabricated by combining the two techniques of electrospinning and atomic layer deposition. The as-prepared samples were annealed at 900 °C under air. Their morphological, structural and optical properties were studied by Scanning Electron Microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Energy-Dispersive X-ray spectroscopy (EDX), UV-visible spectrophotometry, Raman spectroscopy, photoluminescence (PL) and reflectance emission. The performances and long-term stability of these multi co-centric nanotubes for photocatalytic applications…
Morphological and optical property study of Li doped ZnO produced by microwave-assisted solvothermal synthesis
2021
Abstract ZnO materials have been at the centre of many studies for decades. Doping of ZnO by lithium atoms is a prospective approach for compensation of n-type conductivity in the unintentionally doped ZnO aimed at obtaining p-type semiconductor. In this study, we have synthesized ZnO rod-like powders doped with lithium ions (0–0.65 atom%) by the new microwave-assisted solvothermal method in order to obtain greater photoluminescence intensity of ZnO emissions in the UV region. The obtained powders contain nanoparticles from 20 nm up to 250 nm depending on Li content. X-ray diffractometry and Raman spectroscopy were employed to characterise the structure of ZnO powders, scanning electron mic…
Alpha spectrometric characterization of thin $^{233}$U sources for $^{229\text{(m)}}$Th production
2020
Four different techniques were applied for the production of $^{233}$U alpha recoil ion sources, providing $^{229}$Th ions. They were compared with respect to a minimum energy spread of the $^{229}$Th recoil ions, using the emitted alpha particles as an indicator. The techniques of Molecular Plating, Drop-on-Demand inkjet printing, chelation from dilute nitric acid solution on chemically functionalized silicon surfaces, and self-adsorption on passivated titanium surfaces were used. All fabricated sources were characterized by using alpha spectrometry, radiographic imaging, and scanning electron microscopy. A direct validation for the estimated recoil ion rate was obtained by collecting $^{2…
Peculiarities of imaging one- and two-dimensional structures using an electron microscope in the mirror operation mode.
2001
Measurements performed in an electron microscope with the mirror operation mode are most sensitive to local electric fields and geometrical roughness of any kind of the object being studied. The object with a geometrical relief is equivalent to a smooth surface with an effective distribution of microfields. Electrons forming the image interact with the local microfields for an extended time: during approach to the object, deceleration and acceleration away from the object. As a result, the electron trajectories can be strongly distorted, and the contrast changes essentially, leading to image deformation of details of the object under investigation and to lowering of the resolution. These ef…
Time-of-flight photoelectron emission microscopy TOF-PEEM: first results
1998
The time structure of the synchrotron radiation at BESSY (Berlin) is used to operate a photoemission electron microscope in a time-of-flight (TOF) mode. The electrons which are emitted from the sample surface with different energies are dispersed in a drift tube subsequent to the imaging optics. The screen of the microscope was replaced by a fast scintillator (tau = 1.4 ns) and the light is detected by an ultra fast gated intensified CCD camera (800 ps gate 1 MHz repetition rate). The resolving power in the energy domain is demonstrated and possible implications on the spatial resolution (chromatic correction) are discussed. Additionally, an improved contrast at very low emission energies i…
Electron Microscopic Studies of Spruce Needles in Connection with the Occurrence of Novel Forest Decline.
1988
Needles of four spruce trees showing different degrees of novel kinds of forest decline were investigated by electron microscopy. Green needles appearing at least superficially still intact were selected for the present investigation. Most of the mesophyll appeared to be undamaged. However, groups of atypical mesophyll cells were found close to the endodermis or the hypodermis. The chloroplasts of the apparently damaged cells were particularly affected. Changes in the matrix of the chloroplasts, i.e,. increased affinity to osmium, occurrence of extensive nests of plastoglobuli, as well as damage to the membranes, i.e. lesions in the envelope and abnormal thylakoid membranes, were observed. …
Surface structure determination by SEM image processing and electrochemical impedance of graphite+polyethylene composite electrodes
2004
Abstract The electrochemical impedance behaviour of heterogeneous or/and rough electrodes has usually been associated with some geometrical parameters of the surface structure or to a statistical description of the surface properties. An experimental method for sample preparation of graphite + polyethylene composite electrodes based on plasma etching is proposed. After plasma etching, the statistical properties of the electrode, such as the graphite particle size distribution and fractional coverage are measured from scanning electron microscopy pictures using image processing software. The statistical information obtained for the surface is combined with impedance equations of independent …
Localization of antigens PwA33 and La on lampbrush chromosomes and on nucleoplasmic structures in the oocyte of the urodele Pleurodeles waltl: Light …
1994
Monoclonal antibodies A33/22 and La11G7 have been used to study the distribution of the corre-sponding antigens, PwA33 and La, on the lampbrush chromosome loops and nucleoplasmic structures of P. waltl oocytes, using immunofluorescence, confocal laser scanning microscopy and immunogold labeling. The results obtained with these antibodies have been compared with those obtained with the Sm-antigen-specific monoclonal antibody Y12. All these monoclonal antibodies (mAbs) labeled the matrices of the majority of normal loops along their whole length. Nucleoplasmic RNP granules showed a strong staining with the mAbs La11G7 and Y12 throughout their mass, but with the mAb A33/22, they showed only a …
Magneto-optical linear dichroism in threshold photoemission electron microscopy of polycrystalline Fe films.
2000
Magnetic linear dichroism in threshold photoemission has been exploited to obtain magnetic contrast in a photoemission electron microscope using a mercury arc lamp. The dichroism at threshold can be described similar to the magneto-optical Kerr effect in the region of visible light. The asymmetry of electron intensity observed for a 100 nm polycrystalline Fe film on silicon is A=(0.37+/-0.05)%. The asymmetry occurs for the geometry of the transverse Kerr effect. For unpolarized light the asymmetry was about half the value observed for linearly polarized light. Threshold photoemission microscopy has a large potential for high resolution magnetic domain imaging with fast data acquisition.