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Sixty years of the Institute os Scientific Instruments
Müllerová, Ilona
2018 - English
The Institute of Scientific Instruments (ISI) was established in 1957 as an institution providing instrumental equipment for other institutes of the Academy of Sciences, mainly in the field of electron microscopy, nuclear magnetic resonance and coherent optics. Three examples are shown in Figure 1. In the beginning the institute had only 83 employees, including the workshop which produced the electronics and all mechanical parts of the instruments. During the process of post-Communist transformation of the Academy of Sciences, which began in 1989, the development of entire instruments and devices was brought to a halt and scientific activities of our Institute focused on the methodology of probing the physical properties of matter in the above-mentioned main fields. New components of scientific instruments were developed that help push the limits of what hadpreviously been possible, continuing the long tradition of the Institute in these topics.
Keywords:
electron-microscopy; sem
Available at various institutes of the ASCR
Sixty years of the Institute os Scientific Instruments
The Institute of Scientific Instruments (ISI) was established in 1957 as an institution providing instrumental equipment for other institutes of the Academy of Sciences, mainly in the field of ...
Photolitography on flexible substrates
Urbánek, M.; Urbánek, P.; Kuřitka, I.; Kolařík, Vladimír
2018 - English
Nowadays preparation of structures on flexible substrates is highly demanded because of using this patterns in field of flexible electronics. This contribution deals with photolitographic procces for preparation of structures on flexible substrates. The method of photolitography enables to create designed patterns in various material (e.g. metals as conductive layers) on various substrates (silicon wafers, foils, etc.). First the designed pattern is exposed through the mask by UV light into polymer resist, then the pattern is transfered into metal layer by wet etching through the developed windows in resist. In this paper several patterns are prepared through the positive resist PMMA by photolitography into various metal layer (Cu, Al) on flexible substrates.
Keywords:
photolithography; flexible substrates; metal layer
Available at various institutes of the ASCR
Photolitography on flexible substrates
Nowadays preparation of structures on flexible substrates is highly demanded because of using this patterns in field of flexible electronics. This contribution deals with photolitographic procces for ...
Analysis of linear ion Paul traps using 3-D FEM and the azimuthal multipole expansion
Oral, Martin; Číp, Ondřej; Slodička, L.
2018 - English
Radiofrequency (RF) Paul traps are valuable in the design and in the operation of highly stable\noptical atomic clocks based on suitable trapped ions. The traditional setup involves a single\nion in an RF trap irradiated with a laser beam. The frequency of the laser light is then fine-tuned to match that of photons coming from an electronic transition in the atomic shell. The\nachievable frequency stability is about 10-17 for laser-cooled ions. However, the stability can be\nfurther improved by using heavy atoms (such as Thorium) and the more stable frequencies of\ntheir nuclear transitions, and by setting up so-called Coulomb crystals, to improve the frequency measurement statistics by increasing the number of reference atoms. These techniques and their combination could reach relative stabilities beyond 10-20.
Keywords:
linear ion traps; atomic clock; electric RF fields; simulation of electrostatic fields; finite element method; multipole field expansion; ion trajectories; particle tracing
Available at various institutes of the ASCR
Analysis of linear ion Paul traps using 3-D FEM and the azimuthal multipole expansion
Radiofrequency (RF) Paul traps are valuable in the design and in the operation of highly stable\noptical atomic clocks based on suitable trapped ions. The traditional setup involves a single\nion in ...
Orbital motion from optical spin: the extraordinary momentum of circularly polarized light beams
Svak, Vojtěch; Brzobohatý, Oto; Šiler, Martin; Jákl, Petr; Zemánek, Pavel; Simpson, Stephen Hugh
2018 - English
We provide a vivid demonstration of the mechanical effect of transverse spin momentum in an\noptical beam in free space. This component of the Poynting momentum was previously thought\nto be virtual, and unmeasurable. Here, its effect is revealed in the inertial motion of a probe\nparticle in a circularly polarized Gaussian trap, in vacuum. Transverse spin forces combine with\nthermal fluctuations to induce a striking range of non-equilibrium phenomena. With increasing\nbeam power we observe (i) growing departures from energy equipartition, (ii) the formation of\ncoherent, thermally excited orbits and, ultimately, (iii) the ejection of the particle from the trap.\nOur results complement and corroborate recent measurements of spin momentum in evanescent\nwaves, and extend them to a new geometry, in free space. In doing so, we exhibit fundamental,\ngeneric features of the mechanical interaction of circularly polarized light with matter. The work\nalso shows how observations of the under-damped motion of probe particles can provide detailed\ninformation about the nature and morphology of momentum flows in arbitrarily structured light\nfields as well as providing a test bed for elementary non-equilibrium statistical mechanics.
Keywords:
optical trapping; optical levitation; counter-propagating beams; optical spin
Available at various institutes of the ASCR
Orbital motion from optical spin: the extraordinary momentum of circularly polarized light beams
We provide a vivid demonstration of the mechanical effect of transverse spin momentum in an\noptical beam in free space. This component of the Poynting momentum was previously thought\nto be virtual, ...
In vivo study of diatom assemblages using low temperature method for ESEM
Tihlaříková, Eva; Neděla, Vilém; Fránková, Markéta
2017 - English
Diatoms are the most species-rich algal group represented by 12 000 described species and are recognized as powerful bio indicators and used for water quality monitoring. Diatom taxonomy is predominantly based on the morphology of ornate silicified cell wall called frustule composed of two overlapping parts (thecae). This frustule displays intricate patterns and designs unique to each species. For these studies conventional scanning electron microscopy (SEM) was and still is widely used. This method requires cleaning of diatom frustules in strong acids and peroxides followed by conductive coating.This aggressive procedure removes protoplast and damages delicate structures. Environmental scanning electron microscopy (ESEM) brings advantages of observation of fresh diatom material that are presence of whole intact diatom cells, not only empty diatom frustules, extracellular mucilaginous diatom secrets (e.g. pads, stalks, tubes) and whole diatom assemblages directly in situ together with other algal assemblages (e.g. cyanobacteria or green algae). However, in diatom research, ESEM is used mainly for elimination of conductive coating and observation of these organisms in their native wet state adhered directly on the host plant is not yet common. The ESEM observation of native aquatic samples is usually affected with radiation damage that can be lovered by the use of special methods like the Low Temperature Method (LTM) for the ESEM.
Keywords:
ESEM; diatom; morphology; LTM
Available at various institutes of the ASCR
In vivo study of diatom assemblages using low temperature method for ESEM
Diatoms are the most species-rich algal group represented by 12 000 described species and are recognized as powerful bio indicators and used for water quality monitoring. Diatom taxonomy is ...
Nanopatterning of Silicon Nitride Membranes
Matějka, Milan; Krátký, Stanislav; Řiháček, Tomáš; Kolařík, Vladimír; Chlumská, Jana; Urbánek, Michal
2017 - English
Membranes are typically created by a thin silicon nitride (SIN) layer deposited on a silicon wafer. Both, top and bottom side of the wafer is covered by a thin layer of the silicon nitride. The principle of silicon nitride membranes preparation is based on the wet anisotropic etching of the bottom side of the silicon wafer with crystallographic orientation (100). While the basic procedure for the preparation of such membranes is well known, the nano patterning of thin membranes presents quite important challenges. This is partially due to the mechanical stress which is typically presented within such membranes. The resolution requirements of the membrane patterning have gradually increased. Advanced lithographic techniques and etching procedures had to be developed. This paper summarizes theoretical aspects, technological issues and achieved results. The application potential of silicon nitride membranes as a base for multifunctional micro system (MMS) is also\ndiscussed.
Keywords:
e-beam writer; silicon nitride membranes; nano patterning; anisotropic etching
Available at various institutes of the ASCR
Nanopatterning of Silicon Nitride Membranes
Membranes are typically created by a thin silicon nitride (SIN) layer deposited on a silicon wafer. Both, top and bottom side of the wafer is covered by a thin layer of the silicon nitride. The ...
Noise behaviour of field emission cathode based on lead pencil graphite
Knápek, Alexandr; Horáček, Miroslav; Hrubý, František; Šikula, J.; Kuparowitz, T.; Sobola, D.
2017 - English
The paper describes electrical noise of experimental field emission cathodes based on “polymer” pencil leads which have a high content of hybridized carbon with a low degree of surface oxidation and silicon monoxide (SiO). Charge transport within experimental samples is evaluated based on results provided by the noise spectroscopy method. The paper also briefly describes the experimental preparation method of graphite tips based on ion milling which allow obtaining ultrasharp tips of a diameter lower than 100 nm.
Keywords:
field emission; lead pencil graphite; noise spectroscopy
Available at various institutes of the ASCR
Noise behaviour of field emission cathode based on lead pencil graphite
The paper describes electrical noise of experimental field emission cathodes based on “polymer” pencil leads which have a high content of hybridized carbon with a low degree of surface oxidation and ...
Resampling in magnetic resonance spectroscopy-A less model-dependent quantitation quality assessment method
Jabłoński, Michal; Starčuková, Jana; Starčuk jr., Zenon
2017 - English
In this paper we propose a novel method for magnetic resonance spectroscopy (MRS) fitting quality assessment based on time domain resampling of acquired spectra and bootstrapping of the obtained results. The authors introduce two resampling strategies and example results are shown. The proposed method requires MRS data without averaging.
Keywords:
magnetic resonance spektroscopy; quantitation; fitting Quality Assessment
Available at various institutes of the ASCR
Resampling in magnetic resonance spectroscopy-A less model-dependent quantitation quality assessment method
In this paper we propose a novel method for magnetic resonance spectroscopy (MRS) fitting quality assessment based on time domain resampling of acquired spectra and bootstrapping of the obtained ...
Effect of gold coating on emissivity and absorptivity of Ti-6Al-4V alloy
Frolec, Jiří; Králík, Tomáš; Musilová, Věra; Urban, Pavel
2017 - English
The article provides experimental analysis of total hemispherical emissivity and absorptivity of Ti-6Al-4V alloy before and after deposition of 1-2 .pí.m gold layer. We measured their dependences on the temperature of thermal radiation (varying from 20 K to 320 K) and confronted these results with mechanically polished copper, i.e. with material known for extremely low emissivity and absorptivity. Galvanic deposition of pure gold resulted in significant lowering of original emissivity of Ti-6Al-4V bare surfaces from 15.8 percent to 3.4 percent at 300 K and from 4.1 percent to 1.1 percent at 20 K. Our findings about thermal-radiative properties have practical relevance for an improvement of a low temperature part of an ultra-high vacuum scanning probe microscope\n(UHV-SPM) designed by our group and could also be useful for other applications and low temperature systems.
Keywords:
cryogenics; gold films; heat transfer; thermal radiation
Available at various institutes of the ASCR
Effect of gold coating on emissivity and absorptivity of Ti-6Al-4V alloy
The article provides experimental analysis of total hemispherical emissivity and absorptivity of Ti-6Al-4V alloy before and after deposition of 1-2 .pí.m gold layer. We measured their dependences on ...
Role of the superconductivity in radiative heat transfer
Králík, Tomáš; Musilová, Věra; Srnka, Aleš; Fořt, Tomáš; Frolec, Jiří
2017 - English
The absorption and emission of thermal radiation by metals is related to their electrical properties that are influenced by impurities, defects and temperature. We show by some examples of measurements on common metals how different can be the thermal radiative properties. When the heat is transferred across a microscopic vacuum gap in the near field regime, it is possible to achieve a step-like change of the heat\ntransfer based on a superconducting transition. An interesting feature of this effect is the nonlinear thermal conductivity effecting a change of the sign of the differential thermal conductivity across the vacuum gap.
Keywords:
thermal radiation; near field; superconductivity
Available at various institutes of the ASCR
Role of the superconductivity in radiative heat transfer
The absorption and emission of thermal radiation by metals is related to their electrical properties that are influenced by impurities, defects and temperature. We show by some examples of ...
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