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Perspectives in diamond thin film technology
Kromka, Alexander
Synthetic diamond thin films are routinely grown over world not only for basic research but also for industrial uses. At the Institute of Physics (IoP), diamond thin films are grown since 2002. The first installed deposition system is base on microwave plasma enhanced chemical vapor deposition (CVD) in hydrogen reach gas mixture (<2% methane diluted in hydrogen). This system is well suitable for fast growth of high quality diamond films up to 5 cm in diameter. The main advance of the system is cavity like resonator which allows running stable CVD process for several days at relatively high pressures (>200 mbar).
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Study of nucleation and growth of diamond thin films
Ižák, Tibor ; Babchenko, Oleg ; Varga, Marián ; Potocký, Štěpán ; Marton, M. ; Vojs, M. ; Domonkos, Mária ; Kromka, Alexander
This study deals with the nucleation and growth of CVD diamond films on Si substrates. In nucleation part two different nucleation methods were studied: (i) the bias enhanced nucleation (BEN) and (ii) ultrasonic seeding. In the case of BEN, (i) the nucleation time and (ii) the influence of bias voltage were studied. For ultrasonic seeding the effect of different solutions of ultradisperzed detonation nanodiamond (UDD) powder with metal particles on the nucleation efficiency and growth process was investigated (i.e. diamond powder, nanosized Ni, microsized Co and Y metal powders).
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Non-destructive determination of nitrogen in biological and other materials by the photon activation analysis
Krausová, Ivana ; Mizera, Jiří ; Chvátil, David ; Krist, Pavel ; Řanda, Zdeněk ; Kučera, Jan ; Štursa, Jan
The study presents a procedure for assaying nitrogen in biologocial materials by means of instrumental photon activation analysis (IPAA). The determination has been based on counting of the non-specific 511 keV annihilation gamma rays of 13N, product of the photonuclear reaction 14N(γ, n)13N, which is a pure positron emitter. IPAA allowed determination of nitrogen down to 1 wt.%. in selected biological reference materials - NIST RM 8433 Corn Bran, 1547 Peach Leaves, 8414 Bovine Muscle, and 1577b Bovine Liver. The optimized procedure was applied also to assaying nitrogen in pulverized nanodiamond intended for medical purposes.
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Determination of iodine in biological materials by neutron activation analysis
Kučera, Jan
The advantages and disadvantages of various modes of neutron activation analysis (NAA), such as instrumental NAA (INAA), epithermal NAA (ENAA), and radiochemical NAA (RNAA) for iodine determination in biological materials, namely in food and diet samples are briefly reviewed. Examples are given of iodine determination in Asian diet samples by ENAA and RNAA. The accuracy of the results obtained was proved by analyses of numerous US NIST reference materials (RMs) of biological origin.
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Synthesis, structure, and opto-electronic properties of organic dies on diamond
Rezek, Bohuslav ; Čermák, Jan ; Ukraintsev, Egor ; Hubík, Pavel ; Mareš, Jiří J. ; Ledinský, Martin ; Fejfar, Antonín ; Kočka, Jan ; Kromka, Alexander
We prepare a thin-film heterojunction of polypyrrole (Ppy) on hydrogen-terminated diamond by electro-polymerization from solution. We combine advanced scanning techniques (AFM, KFM, micro-Raman) to characterize microscopic structural, chemical, and opto-electronic properties of such system.
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