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Molecular modelling - Structure and Properties of carbene-based catalyst
Kulovaná, Eva ; Zmrzlý, Martin (referee) ; Richtera, Lukáš (advisor)
Molekulové modelování umožňuje předpovídat chování nových látek a napomáhá při jinak obtížné interpretaci experimentálních dat. Záměrem našeho studia byla predikce vybraných vlastností polymeračních katalyzátorů na bázi karbenů, predikce jejich struktur a spektrálních charakteristik. K ověření chování karbenů a jejich prekurzorů ve formě chloridů byly studovány vybrané charakteristiky molekuly. Byla provedena vizualizace vybraných molekulových orbitalů a map elektrostatických potenciálů a elektronových hustot. Následně pomocí počítačových programů byly získány teoretické vazebné délky a úhly vybraných imidazolových a imidazolinových sloučenin a z nich připravených karbenů. Data strukturně podobných, již charakterizovaných sloučenin, byla získána z CCDC (Cambridge Crystallographic Data Centre) a následně konfrontována s námi vypočítanými daty. Byla změřena infračervená (IČ) a Ramanova spektra imidazolové soli a IČ spektrum příslušného karbenu. Tato spektra byla konfrontována s napredikovanými.
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Portable devices for infrared and Raman spectroscopy: methodology of their use within non-invasive survey of paintings in situ
Čermáková, Zdeňka ; Košařová, Veronika
Aim of the methodology is to determine the limits of use of currently available portable IR and Raman spectrometers for the analysis of painted artworks, describe the complicating factors during the measurement and especially within the subsequent interpretation of spectra, which is critical for the overall process. As a result, a practical guidance for the inclusion of non-invasive spectroscopic methods to standard survey of paintings is provided. The methodology is focused on easily portable spectrometers which can be introduce for the analysis of cultural heritage objects directly on-site, and which thereby achieve high flexibility of use.
Fulltext:  PDF; PDF
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Microscopic characterization of graphene material and electronic quality across neighbouring, differently oriented copper grains
Čermák, Jan ; Yamada, T. ; Ganzerová, Kristína ; Rezek, Bohuslav
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.
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Raman tweezers for sorting of living cells
Pilát, Zdeněk ; Ježek, Jan ; Kaňka, Jan ; Šerý, Mojmír ; Jákl, Petr ; Zemánek, Pavel
We have developed an instrument for automatized analysis and sorting of living cells of unicellular algae and other micro-objects based on laser tweezers and Raman spectroscopy. The system comprises the Raman tweezers setup, special microfluidic chip, and a specialized software allowing image recognition, spectral analysis, and automated sorting functions. The resulting instrument allows non-destructive analysis of chemical properties of living cells and their automatic separation for further examination or cultivation.
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Raman tweezers: principle and applications
Bernatová, Silvie ; Samek, Ota ; Pilát, Zdeněk ; Ježek, Jan ; Kaňka, Jan ; Šiler, Martin ; Zemánek, Pavel
Raman tweezers combines the optical trap for non-contact micromanipulation of micro-objects with Raman spectroscopy for chemical analysis of the sample. This combination presents an efficient tool for concurrent spectroscopic analysis of chemical composition and micromanipulation allowing sorting or probing of mechanical properties of the sample. Raman tweezers were successfully used for example in characterization of biomolecules like DNA, for sorting of cells and investigation of the link between their chemical and mechanical properties.
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Growth of diamond thin films: a review
Kromka, Alexander ; Potocký, Štěpán ; Rezek, Bohuslav
Diamond is shown as an extraordinary material which offers promising solution for variety of fundamental studies and industrial uses. Here, growth of synthetic diamond films at low pressures (1 atm) and low temperatures (<1000°C) from carbon consisting gas mixtures is discussed. Variety of chemical vapor deposition techniques are reviewed, their advantages and disadvantages are pointed out too.
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Raman Microspectroscopy of Individual Algal Cells: Sensing Unsaturation of Storage Lipids in vivo
KOTAS, Petr
We have demonstrated the potential of Raman microspectroscopy for the fast and spatially resolved characterization of the composition of selected intracellular regions in individual living cells of three algal species. In particular, we have focused on lipid storage bodies and quantified the degree of unsaturation of algal lipids (iodine value). To verify our results, we developed a method for extraction of storage lipids from highly resistant Trachidiscus minutus cells and determined the fatty acid composition using GC/MS. We have found Raman microspectroscopy to be a fast, versatile, and virtually non-invasive tool for evaluating the potential of different algal species for algal lipid engineering and industry.
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GRAPHENE UNDER UNIAXIAL DEFORMATION: A RAMAN STUDY
Frank, Otakar ; Tsoukleri, G. ; Parthenios, J. ; Papagelis, K. ; Riaz, I. ; Jalil, R. ; Novoselov, K. S. ; Kalbáč, Martin ; Kavan, Ladislav ; Galiotis, C.
The presented work summarizes various aspects of uniaxial deformation in monolayer graphene studied by means of Raman spectroscopy. Graphene flakes were subjected to tension - compression uniaxial loading using the cantilever beam technique. The evolution of the Raman single-resonance (G) and double-resonance (2D) bands was monitored at strain levels < 1%. The position of all peaks redshifts under tension and blueshifts under compression. The G peak splitting into two sub-bands (G(-) and G(+)) which is caused by symmetry lowering, is observed in both strain directions. The sub-bands' intensities are used to calculate the crystal lattice orientation of the measured graphene flakes with respect to the strain axis. The nature and splitting of the 2D band even in the unstrained flakes, when excited by the 785 nm (1.58 eV) laser line, is interpreted as the interplay between two distinct double resonance scattering processes.
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Limitations of spectroscopic methods in the study of earthy pigments
Košařová, V. ; Hradil, David ; Kanický, V.
Nowadays, the spectroscopic methods, above all Infrared Spectroscopy (IR), are the most frequently used analytical methods in the research of cultural heritage, which is mainly caused by easy use and non-invasiveness of these methods and a broad range of their application, which comprises both organic and inorganic substances. Nevertheless, each analytical technique has its detection limits, and the fact that a particular method is suitable for one type of a sample does not automatically mean that it will be appropriate for the identification of another sample. Therefore, the aim of the study is to demonstrate the limitations of both Raman Spectroscopy (RS) and infrared spectroscopy in the study of earthy materials.
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