Institute of Scientific Instruments of the CAS

Brno, Czech Republic

Institute of Scientific Instruments of the CAS

Brno, Czech Republic
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Frank L.,Institute of Scientific Instruments of the CAS | Mikmekova E.,Institute of Scientific Instruments of the CAS | Mikmekova E.,FEI Company | Lejeune M.,University of Picardie Jules Verne
Applied Surface Science | Year: 2017

Electron-beam-induced deposition of various materials from suitable precursors has represented an established branch of nanotechnology for more than a decade. A specific alternative is carbon deposition on the basis of hydrocarbons as precursors that has been applied to grow various nanostructures including masks for subsequent technological steps. Our area of study was unintentional electron-beam-induced carbon deposition from spontaneously adsorbed hydrocarbon molecules. This process traditionally constitutes a challenge for scanning electron microscopy practice preventing one from performing any true surface studies outside an ultrahigh vacuum and without in-situ cleaning of samples, and also jeopardising other electron-optical devices such as electron beam lithographs. Here we show that when reducing the energy of irradiating electrons sufficiently, the e-beam-induced deposition can be converted to e-beam-induced release causing desorption of hydrocarbons and ultimate cleaning of surfaces in both an ultrahigh and a standard high vacuum. Using series of experiments with graphene samples, we demonstrate fundamental features of e-beam-induced desorption and present results of checks for possible radiation damage using Raman spectroscopy that led to optimisation of the electron energy for damage-free cleaning. The method of preventing carbon contamination described here paves the way for greatly enhanced surface sensitivity of imaging and substantially reduced demands on vacuum systems for nanotechnological applications. © 2017 Elsevier B.V.


KarASek V.,Institute of Scientific Instruments of the CAS | Siler M.,Institute of Scientific Instruments of the CAS | Brzobohaty O.,Institute of Scientific Instruments of the CAS | ZemANek P.,Institute of Scientific Instruments of the CAS
Optics Letters | Year: 2017

This theoretical study based on the coupled dipoles model focuses on the dynamics of two optically bound dielectric spheres of unequal sizes confined in counter-propagating incoherent Bessel beams. We analyzed the relative motion of the particles with respect to each other and defined conditions where they form a stable optically bound structure (OBS). We also investigated the motion of the center of mass of the OBS and found that its direction depends on the particle separation in the structure. Besides the optical interaction between objects, we also considered a hydrodynamic coupling in order to obtain more precise results for moving an OBS. © 2017 Optical Society of America.


Jablonski M.,Institute of Scientific Instruments of the CAS | Jablonski M.,Masaryk University | Starcukova J.,Institute of Scientific Instruments of the CAS | Starcuk Z.,Institute of Scientific Instruments of the CAS
BMC Bioinformatics | Year: 2017

Background: Proton magnetic resonance spectroscopy is a non-invasive measurement technique which provides information about concentrations of up to 20 metabolites participating in intracellular biochemical processes. In order to obtain any metabolic information from measured spectra a processing should be done in specialized software, like jMRUI. The processing is interactive and complex and often requires many trials before obtaining a correct result. This paper proposes a jMRUI enhancement for efficient and unambiguous history tracking and file identification. Results: A database storing all processing steps, parameters and files used in processing was developed for jMRUI. The solution was developed in Java, authors used a SQL database for robust storage of parameters and SHA-256 hash code for unambiguous file identification. The developed system was integrated directly in jMRUI and it will be publically available. A graphical user interface was implemented in order to make the user experience more comfortable. The database operation is invisible from the point of view of the common user, all tracking operations are performed in the background. Conclusions: The implemented jMRUI database is a tool that can significantly help the user to track the processing history performed on data in jMRUI. The created tool is oriented to be user-friendly, robust and easy to use. The database GUI allows the user to browse the whole processing history of a selected file and learn e.g. what processing lead to the results, where the original data are stored, to obtain the list of all processing actions performed on spectra. © 2017 The Author(s).


Nedela V.,Institute of Scientific Instruments of the CAS | Tihlarikova E.,Institute of Scientific Instruments of the CAS | Runstuk J.,Institute of Scientific Instruments of the CAS | Hudec J.,Institute of Scientific Instruments of the CAS
Ultramicroscopy | Year: 2018

A new Combined System for high-efficiency detection of Secondary and Backscattered Electrons (CSSBE) in the ESEM consists of three detectors: an ionisation SE detector, an improved scintillation BSE detector, and a new Ionisation Secondary Electron Detector with an electrostatic Separator (ISEDS). The ISEDS optimizes conditions for electron-gas ionisation phenomena in the ESEM to achieve a strongly amplified signal from the secondary electrons with a minimal contribution from backscattered and beam electrons. For this purpose, it is originally equipped with an electrostatic separator, which focuses signal electrons towards a detection electrode and controls the concentration of positive ions above the sample. The working principle of the ISEDS is explained by simulations of signal electron trajectories in gas using the EOD program with our Monte Carlo module. The ability to detect the signal electrons in a selected range of energies is described with Geant4 Monte Carlo simulations of electron-solid interactions and proven by experimental results. High-efficiency detection of the ISEDS is demonstrated by imaging a low atomic number sample under a reduced beam energy of 5 keV, very low beam currents of up to 0.2 pA, and gas pressure of hundreds of Pa. © 2017 Elsevier B.V.


Simpson S.H.,Institute of Scientific Instruments of the CAS | Zemanek P.,Institute of Scientific Instruments of the CAS | Marago O.M.,CNR Institute for Chemical and Physical Processes | Jones P.H.,University College London | Hanna S.,University of Bristol
Nano Letters | Year: 2017

Multiple scattering of light induces structured interactions, or optical binding forces, between collections of small particles. This has been extensively studied in the case of microspheres. However, binding forces are strongly shape dependent: here, we turn our attention to dielectric nanowires. Using a novel numerical model we uncover rich behavior. The extreme geometry of the nanowires produces a sequence of stationary and dynamic states. In linearly polarized light, thermally stable ladder-like structures emerge. Lower symmetry, sagittate arrangements can also arise, whose configurational asymmetry unbalances the optical forces leading to nonconservative, translational motion. Finally, the addition of circular polarization drives a variety of coordinated rotational states whose dynamics expose fundamental properties of optical spin. These results suggest that optical binding can provide an increased level of control over the positions and motions of nanoparticles, opening new possibilities for driven self-organization and heralding a new field of self-assembling optically driven micromachines. © 2017 American Chemical Society.


Smid R.,i-Optics | Hansel A.,Technical University of Delft | Pravdova L.,i-Optics | Sobota J.,Institute of Scientific Instruments of the CAS | And 2 more authors.
Review of Scientific Instruments | Year: 2016

In this work we present a design of an external optical cavity based on Fabry-Perot etalons applied to a 100 MHz Er-doped fiber optical frequency comb working at 1560 nm to increase its repetition frequency. A Fabry-Perot cavity is constructed based on a transportable cage system with two silver mirrors in plano-concave geometry including the mode-matching lenses, fiber coupled collimation package and detection unit. The system enables full 3D angle mirror tilting and x-y off axis movement as well as distance between the mirrors. We demonstrate the increase of repetition frequency by direct measurement of the beat frequency and spectrally by using the virtually imaged phased array images. © 2016 Author(s).


Frolec J.,Institute of Scientific Instruments of the CAS | Kralik T.,Institute of Scientific Instruments of the CAS | Srnka A.,Institute of Scientific Instruments of the CAS
International Journal of Refrigeration | Year: 2017

In order to assess the effect of gold deposition on thermal radiative properties of metallic materials, we measured total hemispherical emissivity and absorptivity of Au layers with a minimal thickness of 1 µm in dependence on the temperature TR of thermal radiation (from 20 K up to 320 K). Technically pure copper or titanium alloy (Ti–6Al–4V) was used as substrate while three types of Au layers were deposited by a sputtering process or a galvanic method. Emissivities among samples with Au layers ranged from 1.8% to 3.9% at room temperature. Galvanic deposition of pure Au lowered the original emissivity of Ti–6Al–4V alloy at 300 K from 15.8% to 3.4%, whereas the same deposition on mechanically polished Cu resulted in increase of emissivity by a factor of three, up to 3.2%. Absorptivity of each sample with Cu or Au surface was lower than its emissivity and showed a weaker dependence on TR. © 2017 Elsevier Ltd and IIR


Navratilova E.,Institute of Scientific Instruments of the CAS | Rovnanikova P.,Brno University of Technology
Construction and Building Materials | Year: 2016

The article deals with the evaluation of six brick dusts which were characterized regarding their chemical and mineralogical composition, amorphous phase content, granulometry and specific surface area. The pozzolanic activity was determined by the modified Chapelle test. The analysed brick dusts were used to prepare modified lime mortars in which lime hydrate was replaced by 50% of brick dust. The flexural and compressive strengths of the mortars were determined and pozzolanic activity was calculated from the compressive strengths. The pozzolanic activity of brick dusts is dependent in particular on their amorphous phase content, particle size distribution and specific surface area. Pozzolanic activity increases with increasing amorphous phase content in the brick dusts. Pozzolanic activity has an effect on the strength of modified lime mortars. The higher is the pozzolanic activity value of the added brick dust the higher are the initial and long term strengths of the modified lime mortars. © 2016 Elsevier Ltd.


Kralik T.,Institute of Scientific Instruments of the CAS | Fort T.,Institute of Scientific Instruments of the CAS | Musilova V.,Institute of Scientific Instruments of the CAS | Srnka A.,Institute of Scientific Instruments of the CAS
Refrigeration Science and Technology | Year: 2016

Radiative heat transfer over short distances smaller than wavelengths in the spectrum of radiating surface is enhanced by near field effect. We studied radiative heat transfer between plane parallel surfaces of niobium films (critical temperature 9 K) sputtered on sapphire. The radiative heat flow was 20 times enhanced above the values given by Planck's law (far-field values) in this measurement. Steep decrease of heat flow by a factor of five, caused by transition to superconducting state, was observed in the near field regime. © 2016, International Institute of Refrigeration. All rights reserved.


PubMed | Institute of Scientific Instruments of the CAS
Type: Journal Article | Journal: BMC bioinformatics | Year: 2017

Proton magnetic resonance spectroscopy is a non-invasive measurement technique which provides information about concentrations of up to 20 metabolites participating in intracellular biochemical processes. In order to obtain any metabolic information from measured spectra a processing should be done in specialized software, like jMRUI. The processing is interactive and complex and often requires many trials before obtaining a correct result. This paper proposes a jMRUI enhancement for efficient and unambiguous history tracking and file identification.A database storing all processing steps, parameters and files used in processing was developed for jMRUI. The solution was developed in Java, authors used a SQL database for robust storage of parameters and SHA-256 hash code for unambiguous file identification. The developed system was integrated directly in jMRUI and it will be publically available. A graphical user interface was implemented in order to make the user experience more comfortable. The database operation is invisible from the point of view of the common user, all tracking operations are performed in the background.The implemented jMRUI database is a tool that can significantly help the user to track the processing history performed on data in jMRUI. The created tool is oriented to be user-friendly, robust and easy to use. The database GUI allows the user to browse the whole processing history of a selected file and learn e.g. what processing lead to the results, where the original data are stored, to obtain the list of all processing actions performed on spectra.

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