Národní úložiště šedé literatury Nalezeno 9 záznamů.  Hledání trvalo 0.01 vteřin. 
Comparative study on functionalization of NCD films with amine groups
Artemenko, Anna ; Kozak, Halyna ; Stuchlík, Jiří ; Biederman, H. ; Kromka, Alexander
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.
Growth of Escherichia coli on nanocrystalline diamond
Jurková, Blanka ; Kozak, Halyna ; Artemenko, Anna ; Ukraintsev, Egor ; Beranová, J. ; Konopásek, I. ; Kromka, Alexander
In this contribution, we compared the attachment of gram-negative model bacterium Escherichia coli to\nuncoated glass and glass coated by hydrogenated and oxidized NCD films. For attachment experiments,\ncontinuous cultivation in commercially available CDC Bioreactor was used. Antibacterial tests indicated\nhigher attachment of gram-negative model bacterium Escherichia coli to NCD surface compared to uncoated\nglass. We assign this effect to higher roughness of NCD surface compared to glass. Bacterial cells preferred\nthe hydrophobic surface of hydrogenated NCD surface to hydrophilic oxidized NCD for their attachment.
In situ XPS characterization of diamond films after AR.sup.+./sup. cluster ion beam sputtering
Artemenko, Anna ; Babchenko, Oleg ; Kozak, Halyna ; Ukraintsev, Egor ; Ižák, Tibor ; Romanyuk, Olexandr ; Potocký, Štěpán ; Kromka, Alexander
In this work, in situ XPS analysis of chemical composition of H- and O-terminated nano- and microcrystalline diamond (NCD and MCD) films before and after their sputtering by the Ar+ cluster ion beam was investigated. Scanning electron microscopy confirmed sputtering of all diamond surfaces with a rate about 0.5 nm/min. Raman spectroscopy and XPS revealed surface graphitization of diamond surface induced by sputtering. Moreover, XPS data showed the presence of about 0.7 % of Ar atoms on the investigated diamond surface after 66 min of sputtering. Also, oxygen residuals were still presented on the H-NCD surface after 66 min of sputtering. In contrast, no oxygen was found on the H-MCD surface just after 2 min of sputtering. Surface composition is discussed in respect to the diamond films growth parameters and surface structure.
Interpretation of the C=O band of modified diamond nanoparticles by means of DFT theory
Jirásek, Vít ; Kozak, Halyna ; Remeš, Zdeněk ; Kromka, Alexander
Diamond nanoparticles (DNPs) are an interesting class of nanomaterials, which has many unique properties. Their applications in medicine and molecular biology have been mentioned. The DNPs were reviewed in sense of their surface chemistry and a range of analytic techniques was pointed out. The experimental analysis can be enhanced by theoretical models based on the first principles. An approach to theoretical analysis of infrared spectra was introduced. As an example, a part of FTIR spectra of the oxidized DNPs was interpreted by means of the DFT theory. The calculation of the C=O stretch vibrational frequencies of carboxylic and anhydride groups on certain model clusters enabled to explain the shift and splitting of the measured spectral bands.
Comparativ study on functionalization of NCD films with amine groups
Artemenko, Anna ; Kozak, Halyna ; Stuchlík, Jiří ; Biederman, H. ; Kromka, Alexander
Nanocrystalline diamond (NCD) films are considered as highly attractive material for biosensing due to its unique semiconducting properties. This can be achieved by modification of NCD films surface on molecular level. Typically chemical immobilization of biomoleculs requires the presence of active functional groups on the diamond surface. This was achieved by attachment of -NH2 functional groups on the surface of H- or O-terminated NCD surface via two plasma-based processes. The first process, deposition of thin amine containing polymer by RF magnetron sputtering of Nylon target in Ar/N2 gas mixture. The second process employs RF plasma treatment in NH3 for 10 minutes. Chemical derivatization (CD) XPS analysis revealed that polymeric coating exhibits a higher amount of amino groups than the diamond surface treated in NH3 RF plasma. Results of I-V measurements showed that surface conductivity of H-terminated NCD films was preserved only after the RF sputtering.
High resolution ATR FTIR spectroscopy of hydrogenated diamond nanoparticles using NCD-coated prism
Remeš, Zdeněk ; Kozak, Halyna ; Rezek, Bohuslav ; Babchenko, Oleg ; Kromka, Alexander ; Girard, H. ; Petit, T. ; Arnault, J. ; Bergonzo, P.
Crucial part of successful ATR - linear antenna CVD NCD. ATR IR spectroscopy compared to transmittance FTIR spectroscopy. IR spectra of diamant nanoparticles adsorbed on NCD surface. Advances of ATR FTIR - higher sensitivity, better resolution, reproducibility.
Electronic transport in intrinsic H-terminated nanocrystaline diamond with various grain size
Hubík, Pavel ; Mareš, Jiří J. ; Kozak, Halyna ; Kromka, Alexander ; Rezek, Bohuslav ; Krištofik, Jozef ; Kindl, Dobroslav
Both effective conductivity and Hall mobility of H-NCD were found to strongly decrease with the diminishing grain size. Effective Hall concentrations (to 1017 m-2) correspond to the true hole concentrations on the surface of the grain interiors. The effective Hall mobility is a robust parameter with respect to the surface conditions.
Pulsed linear antenna microwave plasma – a step ahead in large area material depositions and surface functionalization
Kromka, Alexander ; Babchenko, Oleg ; Ižák, Tibor ; Potocký, Štěpán ; Davydova, Marina ; Neykova, Neda ; Kozak, Halyna ; Remeš, Zdeněk ; Hruška, Karel ; Rezek, Bohuslav
A technological progress in the large area growth of diamond films and carbon nanotubes by the modified linear antenna MW system is presented. We show a correlation between process parameters and nano- or poly-crystalline film character. A challenging part, diamond coated mirrors or ATR prisms, are shown as multifunctional optical elements suitable for detection of absorbed molecules. Additional positive feature of the presented plasma system is low temperature hydrogen functionalization of diamond films. Finally, we present that combination of pulsed MW plasma with radiofrequency substrate biasing results in growth of oriented CNTs over large area.
Linear antenna microwave plasma treatment of diamond
Neykova, Neda ; Kozak, Halyna ; Kromka, Alexander ; Bryknar, Z. ; Vaněček, Milan
The presented works reports on a hydrogen termination of nano-crystalline diamond films performed at low temperature.

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