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Interferometric coordinates measurement sytem for local probe microscopy nanometrology
Hrabina, Jan; Lazar, Josef; Klepetek, P.; Číp, Ondřej; Čížek, Martin; Holá, Miroslava; Šerý, Mojmír
2014 - English
We present an overview of new approaches to the design of nanometrology measuring system with a focus on methodology of nanometrology interferometric techniques and associated problems. The design and development of a nanopositioning setup with interferometric multiaxis monitoring and control involved for scanning probe microscopy techniques (primarily atomic force microscopy, AFM) for detection of the sample profile is presented. Coordinate position sensing allows upgrading the imaging microscope techniques up to quantified measuring. Especially imaging techniques in the micro- and nanoworld overcoming the barrier of resolution given by the wavelength of visible light are a suitable basis for design of measuring systems with the best resolution possible. The system is being developed in cooperation with the Czech metrology institute and it is intended to operate as a national nanometrology standard combining local probe microscopy techniques and sample position control with traceability to the primary standard of length.
Keywords:
Nanometrology; Interferometry; Traceability; Local probe microscopy; Nanopositioning
Available at various institutes of the ASCR
Interferometric coordinates measurement sytem for local probe microscopy nanometrology
We present an overview of new approaches to the design of nanometrology measuring system with a focus on methodology of nanometrology interferometric techniques and associated problems. The design and ...
Temperature Inversion and Heat Transport Against the Temperature Drop in Two-Phase Convection of Cryogenic Helium
Urban, Pavel; Schmoranzer, D.; Hanzelka, Pavel; Skrbek, L.
2014 - English
In the system of two bodies A and B connected by a two-phase vapour-liquid system consisting only of cryogenic helium, we observed anomalous heat transport from the colder but heated body B to the warmer but cooled body A. We noticed this effect during the process of liquid evaporation inside a cylindrical pressure convection cell used for study of Rayleigh-Bénard convection. This anomalous heat transfer occurs under non-equilibrium conditions, owing to the phase transitions that take place inside the cell while temperature inversion develops between the heated but cooler bottom plate and the cooled but warmer top plate. This process is, by virtue of the system being open with respect to heat transport, in no contradiction to the second law of thermodynamics, and a numerical model was formulated that describes the observations with good agreement.
Keywords:
cryogenic helium; two-phase convection; temperature inversion; rain formation; Cryogenics
Available at various institutes of the ASCR
Temperature Inversion and Heat Transport Against the Temperature Drop in Two-Phase Convection of Cryogenic Helium
In the system of two bodies A and B connected by a two-phase vapour-liquid system consisting only of cryogenic helium, we observed anomalous heat transport from the colder but heated body B to the ...
Design and Testing of Low Temperature Part of an UHV – SPM Microscope
Frolec, Jiří; Vonka, J.; Hanzelka, Pavel; Králík, Tomáš; Musilová, Věra; Urban, Pavel
2014 - English
We have developed low temperature part of an ultra high vacuum scanning probe microscope (UHV-SPM) working at variable temperature within the range from 20 K to 700 K. To achieve the required temperature range, a flow cooling system using cryogenic helium (approximately 5 K) as a coolant was designed. The system consists of a flow cryostat and a flexible low-loss transfer line connecting a Dewar vessel with the flow cryostat. We have also tested liquid nitrogen (approximately 77 K) as an alternative low-cost coolant. Using nitrogen, the microscope can operate at temperatures of about 100 K and higher. As the flow of the coolant through the cryostat can cause thermally induced two-phase flow fluctuations resulting in instability in temperatures, preliminary tests were done in order to find ways of avoiding the temperature oscillations and optimising the cooling process.
Keywords:
flow cryostat; VT-SPM; LT-SPM; low conductive support; cryogenics
Available at various institutes of the ASCR
Design and Testing of Low Temperature Part of an UHV – SPM Microscope
We have developed low temperature part of an ultra high vacuum scanning probe microscope (UHV-SPM) working at variable temperature within the range from 20 K to 700 K. To achieve the required ...
Measurement of current density distribution in shaped e-beam writers
Horáček, Miroslav; Bok, Jan; Kolařík, Vladimír; Urbánek, Michal; Matějka, Milan; Krátký, Stanislav
2014 - English
The ZrO W(100) Schottky cathode is used in our e-beam writing system working with a rectangular-shaped electron beam. The homogeneous angular current density distribution is crucial for quality of exposures of the shaped beam lithography systems. Two basic types of the angular emission distribution can be observed in dependence on the microscopic final end form shape of the emitter tip, with bright centre and more common dark centre. The stable operation of the cathode thus stable end form shape requires a delicate balance of parameters inside the gun which however can slightly change during cathode life time. This implies the necessity of analysing and periodical monitoring the current density distribution in e-beam. Four methods enabling this measurement are presented.
Keywords:
e-beam writer; current density
Available at various institutes of the ASCR
Measurement of current density distribution in shaped e-beam writers
The ZrO W(100) Schottky cathode is used in our e-beam writing system working with a rectangular-shaped electron beam. The homogeneous angular current density distribution is crucial for quality of ...
Ultra-low-energy STEM in SEM
Frank, Luděk; Nebesářová, J.; Müllerová, Ilona
2014 - English
Examination of thin samples in TEM or STEM has been performed at hundreds of keV. This energy range offered high resolution but low contrasts which meant that tissue sections had to be contrasted with heavy metal salts. Recent TEM with aberration correctors preserve an acceptable resolution down to 20 keV and provide enhanced contrasts. The LVTEM device is operated at 5 keV on samples thinner than 20 nm. STEM attachments to SEMs have become widespread [3] profiting from an image contrast substantially increasing even for light elements at tens or units of keV. The methods for the preparation of ultrathin sections of various substances are capable of producing layers at and even below 10 nm which enables one to further decrease the energy of the electrons provided the image resolution is maintained. When using the STEM technique virtually all transmitted electrons can be utilised for imaging, while in TEM we are restricted to using electrons capable of forming the final image at acceptable quality. This forces us to narrow the ranges of the angular and energy spreads of electrons that enter the image-forming lenses. Consequently, the STEM technique promises higher contrasts at comparable resolutions. Unlimited reduction of the energy of the illuminating electrons is possible by employing the cathode lens principle. This consists of biasing the sample together with its holder (made flat on both sides) to a high negative potential that retards the incident electrons before they land on the sample surface and accelerates backscattered and transmitted electrons to their respective detectors above and below the sample. Calculations have shown a final spot size only moderately extended even at units of eV so that quality-consistent micrographs can be recorded over the full energy scale.
Keywords:
tissue section; biological STEM; low energy STEM; low energy electrons
Available at various institutes of the ASCR
Ultra-low-energy STEM in SEM
Examination of thin samples in TEM or STEM has been performed at hundreds of keV. This energy range offered high resolution but low contrasts which meant that tissue sections had to be contrasted ...
Photonic Crystal Structure of Butterfly Wing Scales Exhibiting Selective Wavelength Iridescence
Matějková-Plšková, J.; Mika, Filip; Jiwajinda, S.; Dechkrong, P.; Svidenská, S.; Shiojiri, M.
2014 - English
Characteristic patterns and the vivid coloration of the wing scales of butterflies have lately attracted considerable attention as natural photonic crystals. The coloration of butterflies that exhibit human visible iridescence from violet to green has been elucidated. A Sasakia charonda (S. charonda) or ‘great purple emperor’ butterfly was sampled in a woodland in Japan, and an Euploea mulciber (E. mulciber) or 'striped blue crow’ butterfly was reared from an egg at the Environmental Entomology Research and Development Center, Kasetsart University.
Keywords:
butterfly wing; coloration; SEM; TEM; photonic crystal structure
Available at various institutes of the ASCR
Photonic Crystal Structure of Butterfly Wing Scales Exhibiting Selective Wavelength Iridescence
Characteristic patterns and the vivid coloration of the wing scales of butterflies have lately attracted considerable attention as natural photonic crystals. The coloration of butterflies that exhibit ...
Progress in imaging techniques for characterization of polyelectrolyte complex microcapsules as encapsulation matrice for biocatalysts
Bučko, M.; Gemeiner, P.; Vikartovská, A.; Schenkmayerová, A.; Bertóková, A.; Lacík, I.; Chorvát Jr., D.; Neděla, Vilém
2014 - English
Polyelectrolyte complex microcapsules showed to be an univerzal encapsulation matrice for wide range of biocatalysts including viable, native and recombinant bacterial cells, non-viable bacterial cells as well as enzymes. Developed continuous encapsulation protocol based on the polyelectrolyte complexation of oppositely charged polymers enabled production of uniform microcapsules with a controlled shape, size, membrane thickness, permeability and mechanical resistance. The characterisation and control of the microcapsule properties including the inner structure and surface properties was inevitable to determine their proper function and predictability in important applications such as the stabilisation and reuse of encapsulated biocatalysts for more efficient production of valuable compounds. Recent utilisation of unique environmental scanning electron microscope enabled an innovative observation and characterization of capsule morphology in native and fully hydrated state. Achieved results and comparison with previously used conventional microscopic techniques will be presented.
Keywords:
ESEM; matrice for biocatalysts
Available at various institutes of the ASCR
Progress in imaging techniques for characterization of polyelectrolyte complex microcapsules as encapsulation matrice for biocatalysts
Polyelectrolyte complex microcapsules showed to be an univerzal encapsulation matrice for wide range of biocatalysts including viable, native and recombinant bacterial cells, non-viable bacterial ...
Analysis of the gas glow
Hladká, K.; Maxa, J.; Neděla, Vilém; Vyroubal, P.; Vaculík, S.; Hlavatá, P.
2014 - English
In order to optimize the shape of the Differentially pumped chamber in the area of the Primary Electron Beam passage for the current concept of the location of the foci of the Primary Electron Beam, it was necessary to adapt to the size and shape of the limitations of the existing structure. On fig. 1a is the total cross sectional view of the Differentially pumped chamber. Three variants were examined: Current concept with an easily machined shape of the passage of the primary beam, semi-closed concept with a conical shape, cone concept with a wider cone.
Keywords:
SEM; ESEM; gas glow; analysis
Available at various institutes of the ASCR
Analysis of the gas glow
In order to optimize the shape of the Differentially pumped chamber in the area of the Primary Electron Beam passage for the current concept of the location of the foci of the Primary Electron Beam, ...
Beam damage of embedding media sections and their investigations by SEM
Krzyžánek, Vladislav; Novotná, V.; Hrubanová, Kamila; Nebesářová, J.
2014 - English
A scanning transmission electron microscope (STEM) is useful device combining features of scanning and transmission electron microscopes. The sample in form of the ultrathin section is scanned by the electron probe and the transmitted electrons are detected. Except the dedicated STEMs this mode can exist as options in both TEM and SEM. The STEM based on the SEM equipped by a transmission detector was used for presented experiments. Nowadays, such low voltage STEM is more often used, and in many cases replaces the typical TEM. Here, we report investigations of embedding media that are typically used for TEM preparation of biological samples. The STEM detector in SEM may be able to detect both bright-field and dark-fields images. It uses much lower acceleration voltages (30 kV and below) than conventional TEM or STEM. However, materials like biological samples, polymers including embedding media are electron beam sensitive. Two the most important beam damages are the mass loss and the contamination. Both types of damages depend on the used electron energy and the electron dose applied to the sample. The mass loss depends on the sample composition, and the contamination results from the poor vacuum in the specimen chamber of the SEM, cleanness of the sample surface, etc.
Keywords:
beam damage; mass determination; ADF imaging
Available at various institutes of the ASCR
Beam damage of embedding media sections and their investigations by SEM
A scanning transmission electron microscope (STEM) is useful device combining features of scanning and transmission electron microscopes. The sample in form of the ultrathin section is scanned by the ...
Plasmonic Structures In PMMA Resist
Urbánek, Michal; Krátký, Stanislav; Šimík, M.; Kolařík, Vladimír; Horáček, Miroslav; Matějka, Milan
2014 - English
Some metal material can exhibit special physical phenomenon which is called plasmon resonance. This effect can be used in optical applications where designed structures, using this effect, have special function as optical filters, polarizers, holograms etc. This papers deals with preparation of plasmonic structures in poly(methyl methacrylate) (PMMA) resist which is the most common material used for e-beam processing. Designed structures were prepared by e-beam writer with Gaussian beam and accelerating voltage of 100 kV. These structures are usually prepared into negative tone resist hydrogen silsesquioxane (HSQ). We prepared these structures by unusual way into positive resist PMMA due to unavailability and cost of HSQ resist. By this way we are able to achieve high resolution of structures suitable for special optical application. Exposed structures were developed in isopropyl based developer. Final structures after development were coated by two metal layers (first one is Ag layer, second one is gold) by magnetron sputtering and vacuum evaporation. The quality of prepared plasmonic structures was examined by confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM).
Keywords:
electron beam lithography; plasmonic structures; PMMA; metal coating
Available at various institutes of the ASCR
Plasmonic Structures In PMMA Resist
Some metal material can exhibit special physical phenomenon which is called plasmon resonance. This effect can be used in optical applications where designed structures, using this effect, have ...
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