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Characterization of silver nanoparticles
Župková, S. ; Sopoušek, J. ; Šídlo, M. ; Buršík, Jiří
Understanding and characterization of colloidal nanoparticles is very important for their uses in the research and technology. Colloidal silver solutions have many interesting properties such as surface plasmon resonance. Plasmons are optical effects observed for silver, gold, and copper and the other nanoparticles. The value of the wavelength of this effect depends on the particle size and shape as well as on the properties of solvent or absorbent presented. As sample there were used nanoparticles of silver, which were dispersed in aqueous solution. The fluorescence, size and zeta-potential of two samples each with different date of preparation were measured. The colloidal solutions were investigated by means of fluorescence spectroscopy, dynamic light scattering, electron microscopy, and electrophoretic light scattering for zetapotential evaluation.
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Synthesis, structure, and opto-electronic properties of organic dies on diamond
Rezek, Bohuslav ; Čermák, Jan ; Ukraintsev, Egor ; Hubík, Pavel ; Mareš, Jiří J. ; Ledinský, Martin ; Fejfar, Antonín ; Kočka, Jan ; Kromka, Alexander
We prepare a thin-film heterojunction of polypyrrole (Ppy) on hydrogen-terminated diamond by electro-polymerization from solution. We combine advanced scanning techniques (AFM, KFM, micro-Raman) to characterize microscopic structural, chemical, and opto-electronic properties of such system.
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Strength and magnetism of Mn-Pt nanocomposites
Káňa, Tomáš ; Šob, Mojmír
Using ab initio electronic structure calculations, we have analysed Mn atoms dissolved in a platinum matrix, forming thus intermetallics MnPt3, MnPt7 and MnPt15 that can be considered as prototypes of natural Mn–Pt nanocomposites. On the whole, manganese addition makes the resulting Mn–Pt compound softer but increases its resistance to shape deformation. With increasing Mn content, both tensile and compressive theoretical strength is enhanced. In agreement with experiment, our calculations confirm the antiferromagnetic (AFM) ground state of the MnPt7 structure with spins directions altering along the [100] crystallographic direction (AFM [100]). In addition, we have proposed and studied three prototypes of linear MnPt15 nanocomposites consisting of Mn nanochains in the Pt matrix. Again, AFM [100] ordering was found in the ground state of MnPt15.
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