No (412)
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412
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Plasma treatment impact on physical and chemical properties of polymeric fibers
Hlůžek, R.; Prošek, Z.; Trejbal, J.; Fládr, J.; Potocký, Štěpán
2017 - English
Presented work focuses on chemical and physical properties of plasma modified polymeric macro-fibers. Polyethylene terephthalate (PET) and polypropylene (PP) fibers having approx. 300 mu m in diameter were modified using cold oxygen plasma in order to achieve their surface changes needed for durable bond and adhesion with cement matrixes. A duration of plasma modification differed between 5 to 480 seconds, where an effect of the treatment was examined. Fiber surfaces chemical changes were researched via wettability measurement with demineralized water (the measurement was repeated immediately and after 1, 7 and 30 days to find out the changes stability). Physical changes were studied by means of weight balance (determination of weight loss) and tensile strength tests. It was found that wettability was enhanced significantly - up to two times, while mechanical properties of treated fibers decreased only slightly.\n
Keywords:
polymer macro-fibers; plasma treatment; wettability; tensile strength
Available at various institutes of the ASCR
Plasma treatment impact on physical and chemical properties of polymeric fibers
Presented work focuses on chemical and physical properties of plasma modified polymeric macro-fibers. Polyethylene terephthalate (PET) and polypropylene (PP) fibers having approx. 300 mu m in diameter ...
Spatially separated HOMO/LUMO at interface of polypyrrole physisorbed on oxidized nanodiamond facets
Matunová, Petra; Jirásek, Vít; Rezek, Bohuslav
2017 - English
Nanodiamond particles (NDs) have recently risen in popularity owing to their unique and perspective properties. Merging NDs with organic molecules, such as polypyrrole (PPy), into hybrid organic-semiconductor functional systems gives rise to potential applications in photovoltaics (PV), which is supported by prior experimentally observed charge transfer between bulk diamond and PPy. This work focuses on the most relevant (111) and (100) O-terminated ND facets with different coverage of surface terminating oxygens in ether, epoxide, ketone, and peroxide positions. We use density functional theory (DFT) computations employing B3LYP functional and 6-31G(d) basis set. Energetically the most favorable oxidized ND facets were further optimized with PPy in physisorbed configurations. Analysis of geometry, binding energy, HOMO-LUMO gap, and charge transfer was done on the relaxed PPy-ND structures. Multiple hydrogen bonds are formed between PPy amino groups and O atoms on ND surface.
Keywords:
diamond; naoparticules; polypyrrole; density functional theory; charge transfer
Available at various institutes of the ASCR
Spatially separated HOMO/LUMO at interface of polypyrrole physisorbed on oxidized nanodiamond facets
Nanodiamond particles (NDs) have recently risen in popularity owing to their unique and perspective properties. Merging NDs with organic molecules, such as polypyrrole (PPy), into hybrid ...
Surface acoustic waves in the layered systems
Tarasenko, Alexander; Boháč, Petr; Jastrabík, Lubomír
2016 - English
The laser acoustic method was used for analysis of two layered systems: thin titanium and diamond like carbon films both deposited on silicon. The film and substrate parameters are determined by fitting the theoretical curve to the measured dispersion curve. The fit software seeks that set of the system parameters whose theoretical curve coincides the best with the experimental data. For the titanium film the best root-mean square deviation was 2.04 m/s with the relative error < O.I % and for the DLC system the corresponding value was 0.30 m/s (the relative error < O.O1 % ).
Keywords:
laser acoustic method; surface acoustic waves; layered systems; Ti films; diamond-like carbon films
Available at various institutes of the ASCR
Surface acoustic waves in the layered systems
The laser acoustic method was used for analysis of two layered systems: thin titanium and diamond like carbon films both deposited on silicon. The film and substrate parameters are determined by ...
Laser-driven ablation through fast electrons in PALS experiment
Gus'kov, S. Yu.; Chodukowski, T.; Demchenko, N.; Kalinowska, Z.; Kasperczuk, A.; Krouský, Eduard; Pfeifer, Miroslav; Pisarczyk, P.; Pisarczyk, T.; Renner, Oldřich; Skála, Jiří; Šmíd, Michal; Ullschmied, Jiří
2016 - English
Energy transfer to shock wave in Al and Cu targets irradiated by a laser pulse with intensity of I~1-50 PW/cm2 and duration of 250 ps was investigated at Prague Asterix Laser System (PALS). The iodine laser provided energy in the range of 100-600 J at the first and third harmonic frequencies. The focal spot radius of laser beam on the target was varied from 160 to 40 µm. The dominant contribution of fast electron energy transfer into the ablation process was found when using the first harmonic radiation, the focal spot radius of 40-100 µm, and the energy of 300-600 J. The fast electron heating results in the growth of ablation pressure from 60 Mbar at the intensity of 10 PW/cm2 to 180 Mbar at the intensity of 50 PW/cm2 and in the growth of the efficiency of the energy conversion into the shock wave from 2 to 7 % under the conditions of 2D ablation.
Keywords:
laser-produced plasma; ablation pressure
Available at various institutes of the ASCR
Laser-driven ablation through fast electrons in PALS experiment
Energy transfer to shock wave in Al and Cu targets irradiated by a laser pulse with intensity of I~1-50 PW/cm2 and duration of 250 ps was investigated at Prague Asterix Laser System (PALS). The iodine ...
Micro-Raman analysis of samples irradiated at the FLASH facility in Summer 2014 (Report v1-31_05_2016)
Toufarová, Martina; Hájková, Věra; Chalupský, Jaromír; Juha, Libor
2016 - English
The goal of micro-Raman measurements was to indicate a presence of the carbon black grown in the FEL-illuminated areas on the sample surface. Twelve samples have been investigated and results have been reported to the X-ray Optics Group at the University of Twente.
Keywords:
radiation damage; carbon black; free-electron laser; soft x-rays; Raman spectroscopy
Available at various institutes of the ASCR
Micro-Raman analysis of samples irradiated at the FLASH facility in Summer 2014 (Report v1-31_05_2016)
The goal of micro-Raman measurements was to indicate a presence of the carbon black grown in the FEL-illuminated areas on the sample surface. Twelve samples have been investigated and results have ...
Geometric resonances in reflectivity spectra of lead zirconate
Dočekalová, Zuzana; Hlinka, Jiří
2016 - English
The paper deals with effects of domain boundaries on the THz–frequency range dispersion of the complex dielectric permitivity tensor of lead zirconate. In the case of a sufficiently narrow domain widths (in comparison to the wave–length of the light used in the experiment), the effective–medium average permittivity shows additional peaks identified as geometric resonances, i.e. extraneous excitations created by thematerial interface. Features of the far–infrared reflectivity spectra of the twinned lead zirconate crystal in the limit of narrow and wide domains are estimated with the\nhelp of the damped harmonic oscillator model with paramaters fully determined fromrecent experiments.
Keywords:
geometric resonances; lead zirconate; antiferroelectrics; reflectivity; phonon
Available at various institutes of the ASCR
Geometric resonances in reflectivity spectra of lead zirconate
The paper deals with effects of domain boundaries on the THz–frequency range dispersion of the complex dielectric permitivity tensor of lead zirconate. In the case of a sufficiently narrow domain ...
Book of Abstracts of the 26th Joint Seminar Development of Materials Science in Research and Education
Kožíšek, Zdeněk; Král, Robert; Zemenová, Petra
2016 - English
Topics:\n- Trends in development of materials research\n- Education of materials science at the universities\n- Information about the research programmes of individual institutions\n- Information on equipment for preparation and characterisation of materials\n- Results of materials science research
Keywords:
material sciences
Available at various institutes of the ASCR
Book of Abstracts of the 26th Joint Seminar Development of Materials Science in Research and Education
Topics:\n- Trends in development of materials research\n- Education of materials science at the universities\n- Information about the research programmes of individual institutions\n- Information on ...
Cryogenic cooling system Brayton for 10 J/10 Hz Yb:YAG multi-slab based laser system at ELI-Beamlines project
Schustr, P.; Fibrich, Martin; Polan, Jiří; Rus, Bedřich; Dostálová, M.; Valdislav, P.; Simek, J.
2016 - English
We present design and operational prototype of cryogenic cooling system based on Bryton's cycle for 10J/10Hz Yb:YAG multi-slab laser system at ELI-Beamlines project.
Keywords:
Brayton; cryogenics; laser; cooling; ytterbium; design; prototype
Available at various institutes of the ASCR
Cryogenic cooling system Brayton for 10 J/10 Hz Yb:YAG multi-slab based laser system at ELI-Beamlines project
We present design and operational prototype of cryogenic cooling system based on Bryton's cycle for 10J/10Hz Yb:YAG multi-slab laser system at ELI-Beamlines project.
Microscopic characterization of graphene material and electronic quality across neighbouring, differently oriented copper grains
Čermák, Jan; Yamada, T.; Ganzerová, Kristína; Rezek, Bohuslav
2015 - English
We study graphene grown across the boundary of three such grains having bright, medium, and dark color in reflection. Raman micro-spectroscopy proves presence of mostly a monoor bi-layer graphene on all the grains. Yet intensity of Raman 2D band is grain-dependent: highest at the darkest grain and lowest at the brightest one. Contrary, conductive atomic force microscopy detects the highest conductivity at the brightest grain and the lowest current at the darkest grain. This is attributed to dominant electrical current path through graphene and underlying oxide thickness of which also depends on the type of copper grain. We correlate and discuss the results with view to better understanding of graphene growth and electronic properties on large area copper substrates.
Keywords:
graphene; chemical vapor deposition; atomic force microscopy; Raman spectroscopy; electronic properties
Available at various institutes of the ASCR
Microscopic characterization of graphene material and electronic quality across neighbouring, differently oriented copper grains
We study graphene grown across the boundary of three such grains having bright, medium, and dark color in reflection. Raman micro-spectroscopy proves presence of mostly a monoor bi-layer graphene on ...
Magnetic domains under mechanical stress in single crystal Ni-Mn-Ga
Kopecký, Vít; Heczko, Oleg
2015 - English
The complexity of Ni-Mn-Ga single crystal lies in combination of ferromagnetic domain structure and ferroelastic twinned microstructure. Magnetic domain structure for different twinned microstructure was studied using magneto-optical indicator film. Different orientations of magnetic domains can be observed at the same place of the sample thanks to magnetically induced structural reorientation by movement of twin boundaries. We investigated experimentally the changes of magnetic domain structure in the vicinity of mobile a/c twin boundary.
Keywords:
Ni-Mn-Ga; magnetic domains; twin boundary
Available at various institutes of the ASCR
Magnetic domains under mechanical stress in single crystal Ni-Mn-Ga
The complexity of Ni-Mn-Ga single crystal lies in combination of ferromagnetic domain structure and ferroelastic twinned microstructure. Magnetic domain structure for different twinned ...
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