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Characterization Methods for Nanoparticles
Published in C. Anandharamakrishnan, S. Parthasarathi, Food Nanotechnology, 2019
R. Gopirajah, C. Anandharamakrishnan
Once a sample is irradiated with a parallel beam of monochromatic X-rays, the atomic lattice of the sample acts as a three-dimensional diffraction grating causing the X-ray beam to be diffracted to specific angles (Warren, 1941). As shown in Figure 16.6, a diffractometer can be used to make a diffraction pattern of a crystalline solid (Chandrasekaran, 1998). The essential parts of the diffractometer include X-ray tube (source of X-ray), incident beam optics (conditions the X-ray before hitting the sample), sample holder, and detector (counts the number of X-rays scattered by the sample). During XRD analysis, X-ray beams are reflected off the parallel atomic layers within a molecule over a range of diffraction angles. Because the X-ray beam has a single specific wavelength, constructive or destructive interference can occur. At certain angles, the reflected rays are in phase (constructive interference), and this will give a peak in a diffractogram. From the diffraction pattern, one can identify the molecule or mixture of molecules. More or less like a fingerprint, every molecule has its distinct set of diffraction peaks that can be used to identify it. Identification of the molecules is usually done by comparing the measured diffractogram with a database of known diffraction data.
Measurement of grading in heteroepitaxial layers
Published in A G Cullis, S M Davidson, G R Booker, Microscopy of Semiconducting Materials, 1983, 2020
M A G Halliwell, J Juler, A G Norman
The optical communications devices currently being developed at BTRL are fabricated from heteroepitaxial layers. The new generation of detectors are made from gallium indium arsenide layers on indium phosphide substrates. In order to produce satisfactory devices the composition of the layers must be controlled such that the lattice parameter difference between layer and substrate is small. The procedure for measuring lattice parameter differences between epitaxial layers and substrates, using the double crystal diffractometer is well established (Halliwell, 1981). In the diffractometer the x-ray beam is diffracted by a slice of substrate material followed by diffraction from the sample. The sample is rotated through the Bragg condition and the resulting variation of intensity with angle is known as the “rockingcurve”. Detailed analysis of peak shapes of the rocking curves recorded from heteoepitaxial layers has not yet been developed. In this paper we present a preliminary attempt to derive theoretical rocking curves for graded layers of gallium indium arsenide on indium phosphide. The layers are assumed to have a low density of crystalline defects such as dislocations and stacking faults. A variation of composition within the layer will be accompanied by a variation in lattice parameter and we would expect the layer peak to be broadened. In order to calculate the rocking curves in the presence of a lattice parameter gradient, we represented the layer by a series of laminae each with a different constant lattice parameter. In this preliminary report thelayers were subdivided into laminae of equal thickness with equal lattice parameter differences between them to model linear grading with depth.
The green-synthesized zinc oxide nanoparticle as a novel natural apoptosis inducer in human breast (MCF7 and MDA-MB231) and colon (HT-29) cancer cells
Published in Inorganic and Nano-Metal Chemistry, 2020
Seyed Hosein Boskabadi, Saeideh Zafar Balanezhad, Ali Neamati, Masoud Homayouni Tabrizi
We synthesized ZnONPs by making changes in Santhoshkumar et al. methodolgy.[40] In this regard, a 100 mL solution containing 10 g Ferula assa-foetida powder was prepared and filtered. After making a 500 mL second solution containing 46 g Zinc acetate [Zn (O2CCH3)2(H2O)2], the sample solution was made up of 10 mL Ferula assa-foetida and 100 mL zinc acetate solutions, and then mixed by magnetic stirrer at 37 °C for 4 h. The white color indicated the synthesized-ZnONPs. We measured the ZnONPs size and density pattern by an X-ray diffractometer (PAN analytical X-Pert PRO, China) and performed X-ray crystallography by applying CuKα radiation (1.54060 Å) to analyze the X-ray diffraction (XRD) properties of NPs. Moreover, the FTIR spectra were determined at 4 cm−1 resolution by FTIR spectrometry (Perkin Elmer, Walthman, MA, USA).[23] Finally, the NPs’ size and shape were evaluated by TEM (HT7800 RuliTEM, Hitachi High-Tech, Japan) and SEM (S-3700N, Hitachi High-Tech, Japan), respectively.
Synthesis and photophysical properties of conjugated thioketone, thioketone S-oxide (Sulfine), and related compounds incorporated in a dibenzobarrelene skeleton
Published in Journal of Sulfur Chemistry, 2020
Akihiko Ishii, Ryota Ebina, Mari Shibata, Yuki Hayashi, Norio Nakata
All melting points were determined on a Mel-Temp capillary tube apparatus and were uncorrected. 1H and 13C NMR spectra were recorded on Bruker AVANCE-400 (400 MHz for 1H and 101 MHz for 13C) or AVANCE-500 (500 MHz for 1H) spectrometers using CDCl3 as the solvent at room temperature. UV-Vis spectra were recorded on a HITACHI U-1900 spectrophotometer. Fluorescence spectra were recorded on a JASCO FP-6600 spectrofluorometer. Absolute photoluminescence quantum yields were measured by a calibrated integrating sphere system C10027 (Hamamatsu Photonics K.K.). Emission lifetimes were obtained with a Hamamatsu Photonics K.K. Quantaurus-Tau fluorescence lifetime spectrometer. Elemental analyses were carried out at the Molecular Analysis and Life Science Center of Saitama University. X-ray crystallography was performed with a Bruker AXS SMART diffractometer. Solvents were dried by standard methods and freshly distilled prior to use. Column chromatography was performed with silica gel (70-230 mesh) and the eluent is shown in parentheses. All theoretical calculations were performed with the Gaussian 09 package [54]. Photoisomerization between (Z)-10 and (E)-10 was carried out with a light generated from a blacklight blue lamp (FLP27BLB, Sankyo Denki Co., Ltd.); the light centered at 365 nm was filtered with a yellow cellophane to reduce the intensity to less than 1%.
Preparation of cubic SiC from δ-Na2Si2O5/carbon nanocomposite using cobalt catalyst
Published in Science and Technology of Advanced Materials, 2019
Powder X-ray diffraction (XRD) measurements were performed using a Rigaku Rotaflex 200B diffractometer equipped with Cu Kα X-ray radiation and a curved crystal graphite monochromator. The scanning electron micrographs (SEMs) were recorded with a JEOL JSM-840A scanning electron microscope. The transmission electron micrographs (TEM) were obtained with a JEOL JEM-200 CX transmission electron microscope operated at 200 kV, using a thin-section technique. The powder samples were embedded in epoxy resin and then sectioned with an ultramicrotome. Nitrogen adsorption/desorption isotherms were determined at 77 K using Micromeritics ASAP 2020. All samples were outgassed at 300°C under vacuum for 4 h. The specific surface areas were determined by the Brunauer-Emmett-Teller (BET) equation.