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Controlled structuring of self-assembled polystyrene microsphere arrays by two different plasma systems
Domonkos, Mária; Ižák, Tibor; Stolcova, L.; Proška, J.; Kromka, Alexander
2014 - English
In this study we present a successful manipulation of microspheres by reactive ion etching (RIE). A self-assembled monolayer close-packed array of monodisperse polystyrene microspheres (PM) with diameter of 471 nm was used as the primary template. The PM templates were processed in two different RIE systems: (i) capacitively coupled radiofrequency plasma (CCP) and (ii) dual plasma system which combines CCP and pulsed linear-antenna microwave plasma (PLAMWP). The influence of process conditions on the PM geometry was systematically studied by scanning electron microscopy (SEM). It was found out that choosing optimal parameters results in a tunable diameter of PM with various shapes (from spheres to pyramid-like structures) while keeping their periodic hexagonal ordering.
Keywords:
nanosphere lithography; reactive ion etching; pulsed linear-antenna microwave plasma; polystyrene microspheres; Langmuir-Blodgett monolayers
Available at various institutes of the ASCR
Controlled structuring of self-assembled polystyrene microsphere arrays by two different plasma systems
In this study we present a successful manipulation of microspheres by reactive ion etching (RIE). A self-assembled monolayer close-packed array of monodisperse polystyrene microspheres (PM) with ...
Safety aspects of usage of flammable and toxic gases in high power laser accelerator experiments
Procházka, Petr; Prokůpek, J.; Perales, B.
2014 - English
High power laser accelerators are promising technologies that can effectively decrease the space and potentially cost of the particle acceleration experiments. For many of them there is a technical demand to use flammable and toxic gases as targets for lasers or for accelerated particles. Their usage, however, brings many challenges for design of the technology and safety management system of the facility.
Keywords:
high power laser; accelerator
Available at various institutes of the ASCR
Safety aspects of usage of flammable and toxic gases in high power laser accelerator experiments
High power laser accelerators are promising technologies that can effectively decrease the space and potentially cost of the particle acceleration experiments. For many of them there is a technical ...
Rapid and sensitive determination of metformin in human urine and serum by capillary electrophoresis with contactless conductivity detection
Tůma, P.; Fauknerová-Matějčková, J.; Jurka, Vlastimil; Samcová, E.
2014 - Czech
Capillary electrophoresis with contactless conductivity detection has been used for direct determination of the antidiabetic drug metformin in human urine and serum. Metformin is separated in 2 M acetic acid as background electrolyte. The monitoring of metformin levels in urine is performed on the shord separation path under high electric intensity. Tento příspěvek je zaměřen na vývoj velmi rychlého kapilárně elektroforetického (CE) stanovení metforminu v lidské moči a séru. Úprava moče i séra před CE analýzou je velmi jednoduchá a spočívá pouze v ředění tělní tekutiny popřípadě deproteinizaci vzorku.
Keywords:
capillary electrophoresis; contractless conductivity detection; large volume sample stacking; metformin
Available at various institutes of the ASCR
Rapid and sensitive determination of metformin in human urine and serum by capillary electrophoresis with contactless conductivity detection
Capillary electrophoresis with contactless conductivity detection has been used for direct determination of the antidiabetic drug metformin in human urine and serum. Metformin is separated in 2 M ...
Comparative study on functionalization of NCD films with amine groups
Artemenko, Anna; Kozak, Halyna; Stuchlík, Jiří; Biederman, H.; Kromka, Alexander
2014 - English
Two plasma-based processes for functionalization of oxygen or hydrogen terminated NCD surfaces with amino groups were compared. The first process was based on deposition of thin (8 nm) amine containing plasma polymer by RF magnetron sputtering of Nylon target in Ar/N-2 working gas mixture. RF plasma treatment in NH3 for 10 minutes was used in the second process. The properties of NCD films before and after amination were characterized by scanning electron microscopy (SEM), wettability measurements, spectral ellipsometry, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and current-voltage (I-V) measurements. The presence of nitrogen (and thus amino groups) on the surface was confirmed by XPS measurements in both cases. The obtained results indicated that NCD surface functionalization from amine containing plasma polymer by RF magnetron sputtering is an alternative technological solution for successful functionalization of diamond surfaces for biosensor applications.
Keywords:
diamond; amino functionalization; XPS; surface conductivity
Available at various institutes of the ASCR
Comparative study on functionalization of NCD films with amine groups
Two plasma-based processes for functionalization of oxygen or hydrogen terminated NCD surfaces with amino groups were compared. The first process was based on deposition of thin (8 nm) amine ...
Model of static recrystallization in the coarse-grained B2 iron aluminide
Schindler, I.; Šumšal, V.; Kopeček, Jaromír; Kawulok, P.; Jozwik, P.; Rusz, S.; Kawulok, R.; Opěla, P.
2014 - English
Microstructure of the laboratory castings made from Fe-40at.%Al-Zr-B alloy was homogenized by the multipass hot rolling in protective capsules and subsequent lannealing. Based on the isothermal hot compression tests and EBSD analysis, the sufficiently accurate model describing the static recrystalization kinetics of the such prepared coarse-grained B2 iron aluminide after strain 0.2 was developed. The independent variables in this model are temperature of deformation as well as annealing time equal to the deformation temperature. Unexpected effect of the previous strain value on the static softening was observed. Static recrystallization begins relatively easy in the studied alloy in the whole range of testing temperatures (900-1100 °C), but a very long-term annealing is quite necessary for the complete course of recrystallization.\n
Keywords:
iron aluminide; hot compression test; microstructure; EBSD; static recrystallization
Available at various institutes of the ASCR
Model of static recrystallization in the coarse-grained B2 iron aluminide
Microstructure of the laboratory castings made from Fe-40at.%Al-Zr-B alloy was homogenized by the multipass hot rolling in protective capsules and subsequent lannealing. Based on the isothermal hot ...
Nanopositioning with detection of a standing wave
Holá, M.; Hrabina, J.; Číp, O.; Fejfar, Antonín; Stuchlík, Jiří; Kočka, Jan; Oulehla, J.; Lazar, J.
2014 - English
A measuring technique is intended for displacement and position sensing over a limited range with detection of standing-wave pattern inside of a passive Fabry-Perot cavity. In this concept we consider locking of the laser optical frequency and the length of the Fabry-Perot cavity in resonance. Fixing the length of the cavity to e.g. a highly stable mechanical reference allows stabilizing wavelength of the laser in air and thus to eliminate especially the faster fluctuations of refractive index of air due to air flow and inhomogeneity. Detection of the interference maxima and minima within the Fabry-Perot cavity along the beam axis has been tested and proven with a low loss transparent photodetector with very low reflectivity. The transparent photodetector is based on a thin polycrystalline silicon layer. Reduction of losses was achieved thanks to a design as an optimized set of interference layers acting as an antireflection coating. The principle is demonstrated on an experimental setup.
Keywords:
nanometrology; nanopositioning; Fabry-Perot cavity; standing wave; interferometry
Available at various institutes of the ASCR
Nanopositioning with detection of a standing wave
A measuring technique is intended for displacement and position sensing over a limited range with detection of standing-wave pattern inside of a passive Fabry-Perot cavity. In this concept we consider ...
Characterisation of InAs/GaAs quantum dots by high resolution transmission electron microscopy
Zíková, Markéta; Hospodková, Alice; Pangrác, Jiří; Hulicius, Eduard; Komninou, Ph.; Kioseoglou, J.
2014 - English
The InAs/GaAs quantum dots (QDs) covered by GaAsSb strain reducing layer (SRL) have suitable properties for various applications. The GaAsSb SRL covering InAs QDs is used to improve the structure growth and the final parameters like QD density, QD size or photoluminesence. To obtain high-quality structure with required properties, the structure growth and final structure have to be deeply studied. Since the QDs and SRL system is surrounded by GaAs, the high resolution transmission electron microscopy (HRTEM) measurement was used to reveal the real material arrangement in a prepared sample. In this work we will discuss the results of following HRTEM measurements: flatness and thickness of prepared layers, QD size, atomic arrangement and composition of GaAsSb layer.
Keywords:
quantum dot; InAs; GaAsSb; high resolution transmission electron microscopy
Available at various institutes of the ASCR
Characterisation of InAs/GaAs quantum dots by high resolution transmission electron microscopy
The InAs/GaAs quantum dots (QDs) covered by GaAsSb strain reducing layer (SRL) have suitable properties for various applications. The GaAsSb SRL covering InAs QDs is used to improve the structure ...
Applications of self-assembled 2D polystyrene nanosphere arrays
Domonkos, Mária; Ižák, Tibor; Demo, Pavel; Kromka, Alexander
2014 - English
In this study nanosphere lithography (NSL) is demonstrated to be a low-cost, parallel and material independent fabrication process for creating periodic arrays of nanostructures using self-assembled nanospheres as templates. SA is the most feasible way to fabricate 2D or 3D colloidal crystals on large areas. After the mask preparation NSL uses different steps of plasma etching and deposition processes. The resulting patterned nanostructures have a wide range of applications in many important areas such as photonics, antireflection, surface wetting, biological and chemical sensing, solar cells, etc. This study focuses on an overview of applications of 2D colloidal crystals. First, structuring of substrate surfaces and the creation of various nano-objects (nanotips, nanopillars, nanocones) is shown. Next, direct growth of patterned structures (graphene nanomesh and diamond structures) is pointed out.
Keywords:
nanosphere lithography; nanostructuring; polystyrene microspheres; reactive ion etching
Available at various institutes of the ASCR
Applications of self-assembled 2D polystyrene nanosphere arrays
In this study nanosphere lithography (NSL) is demonstrated to be a low-cost, parallel and material independent fabrication process for creating periodic arrays of nanostructures using self-assembled ...
Photocatalytic activity of ZnxCd.sub.1-x./sub.S quantum dots in dependence on their composition
Praus, P.; Svoboda, L.; Hospodková, Alice; Mamulová-Kutláková, K.
2014 - English
ZnxCd1-xS quantum dots (QDs) with the different composition x were prepared by precipitation of Zn and Cd acetates with sodium sulphide from aqueous colloid dispersions. Transition energies of these QDs were determined from UV-VIS spectra of the QDs colloid dispersions and consequently used for calculation of the QDs sizes according to the Schrödinger equation. The ZnCdS QDs size was found to be significantly influenced by their composition, decreased with increasing the Zn content. The QDs were also characterized by TEM, X-ray powder diffraction and PL. The photocatalytic activity of the QDs was studied using the methylene blue decomposition under UV irradiation with the maximum intensity of 365 nm. Different photocatalytic activity depending on the composition x was observed. Quantum levels of the QDs have important influence on their photocatalytic activity as a result of quantum size effect. The maximal photocatalytic activity was achieved for x=0.6.
Keywords:
quantum dots; ZnCdS; photocatalysis
Available at various institutes of the ASCR
Photocatalytic activity of ZnxCd.sub.1-x./sub.S quantum dots in dependence on their composition
ZnxCd1-xS quantum dots (QDs) with the different composition x were prepared by precipitation of Zn and Cd acetates with sodium sulphide from aqueous colloid dispersions. Transition energies of these ...
Magnetic measurement of fatigue damage level of ferromagnetic construction materials
Tomáš, Ivan; Vejvoda, S.; Kovářík, O.
2014 - Czech
Main principles of the lately introduced method of Magnetic Adaptive Testing (MAT) are described. The method is applied to measurement of the fatigue damage level and residual lifetime of technical objects manufactured from ferromagnetic construction materials. The up-to-now existing experiments and experience gave satisfactory and promissing results. V příspěvku jsou popsány principy nedávno zavedené metody Magnetického adaptivního testování, aplikované zde na měření úrovně únavového poškození a zbytkové životnosti objektů vyrobených z feromagnetických konstrukčních materiálů. Dosavadní experimenty a zkušenosti zatím vedou k uspokojivým výsledkům.
Keywords:
magnetic adaptive testing
Available at various institutes of the ASCR
Magnetic measurement of fatigue damage level of ferromagnetic construction materials
Main principles of the lately introduced method of Magnetic Adaptive Testing (MAT) are described. The method is applied to measurement of the fatigue damage level and residual lifetime of technical ...
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