Location: Šlechtitelů 11, Olomouc
Phone: (+420) 58 563 4959
Fax: (+420) 58 563 4958
Oblast výzkumu:
Conversion electron Mössbauer spectroscopy
Kvalifikace:
Mgr.: Applied physics, Palacký University
Publications
2011
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J. Pechousek, R. Prochazka, V. Prochazka, and J. Frydrych, “Virtual instrumentation technique used in the nuclear digital signal
processing system design: Energy and time measurement tests,” NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION
A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT, vol. 637, iss. 1, pp. 200-205, 2011.
[Bibtex]@article ISI:000289608000026, Author = Pechousek, J. and Prochazka, R. and Prochazka, V. and Frydrych, J., Title = Virtual instrumentation technique used in the nuclear digital signal processing system design: Energy and time measurement tests, Journal = NUCLEAR INSTRUMENTS \& METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT, Year = 2011, Volume = 637, Number = 1, Pages = 200-205, Month = MAY 1, Abstract = In this report, computer-based digital signal processing system with a 200 MS s(-1) sampling digitizer is presented. Virtual instrumentation technique is used to easily develop a system which provides spectroscopy measurements such as amplitude and time signal analysis, with the time-of-flight facility. Several test measurements were performed to determine the characteristics of a system. The presented system may find its application in the coincidence measurement since the system is usable for different types of detectors and sensitive to decay lifetimes from tens of nanoseconds to seconds. (C) 2011 Elsevier B.V. All rights reserved., DOI = 10.1016/j.nima.2011.02.024, ISSN = 0168-9002, Unique-ID = ISI:000289608000026,
2010
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J. Frydrych, L. Machala, M. Hermanek, I. Medrik, M. Mashlan, J. Tucek, J. Pechousek, and V. K. Sharma, “A nanocrystalline hematite film prepared from iron(III) chloride
precursor,” THIN SOLID FILMS, vol. 518, iss. 21, pp. 5916-5919, 2010.
[Bibtex]@article ISI:000280989100008, Author = Frydrych, Jiri and Machala, Libor and Hermanek, Martin and Medrik, Ivo and Mashlan, Miroslav and Tucek, Jiri and Pechousek, Jiri and Sharma, Virender K., Title = A nanocrystalline hematite film prepared from iron(III) chloride precursor, Journal = THIN SOLID FILMS, Year = 2010, Volume = 518, Number = 21, Pages = 5916-5919, Month = AUG 31, Abstract = This paper deals with a simple and low-cost method developed to deposit hematite (alpha-Fe(2)O(3)) layers on a fluorine-doped tin oxide (FTO/F center dot SnO(2)) substrate by thermal decomposition of solid iron(III) chloride hexahydrate (FeCl(3) 6H(2)O) Deposition procedure takes place through chemical intermediate iron(III) oxide chloride (FeOCl) film. A crucial influence of atmosphere dynamics involved in the calcination process of FeOCl has been observed As-deposited films were characterized by means of Conversion Electron Mossbauer Spectroscopy (CEMS), Grazing Angle X-Ray Diffractometry (GAXRD), Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX) analysis Final nanocrystalline hematite film with a cactus-field-like design consists of 20 nm thick porous crystal plates. A process of hematite doping by tin atoms from substrate coating is also discussed (C) 2010 Elsevier B V. All rights reserved., DOI = 10.1016/j.tsf.2010.05.081, ISSN = 0040-6090, Unique-ID = ISI:000280989100008, -
K. Sivula, R. Zboril, F. Le Formal, R. Robert, A. Weidenkaff, J. Tucek, J. Frydrych, and M. Graetzel, “Photoelectrochemical Water Splitting with Mesoporous Hematite Prepared
by a Solution-Based Colloidal Approach,” JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, vol. 132, iss. 21, pp. 7436-7444, 2010.
[Bibtex]@article ISI:000278190600045, Author = Sivula, Kevin and Zboril, Radek and Le Formal, Florian and Robert, Rosa and Weidenkaff, Anke and Tucek, Jiri and Frydrych, Jiri and Graetzel, Michael, Title = Photoelectrochemical Water Splitting with Mesoporous Hematite Prepared by a Solution-Based Colloidal Approach, Journal = JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, Year = 2010, Volume = 132, Number = 21, Pages = 7436-7444, Month = JUN 2, Abstract = Sustainable hydrogen production through photoelectrochemical water splitting using hematite (alpha-Fe(2)O(3)) is a promising approach for the chemical storage of solar energy, but is complicated by the material's nonoptimal optoelectronic properties. Nanostructuring approaches have been shown to increase the performance of hematite, but the ideal nanostructure giving high efficiencies for all absorbed light wavelengths remains elusive. Here, we report for the first time mesoporous hematite photoelectodes prepared by a solution-based colloidal method which yield water-splitting photocurrents of 0.56 mA cm(-2) under standard conditions (AM 1.5G 100 mW cm(-2), 1.23 V vs reversible hydrogen electrode, RHE) and over 1.0 mA cm(-2) before the dark current onset (1.55 V vs RHE). The sintering temperature is found to increase the average particle size, and have a drastic effect on the photoactivity. X-ray photoelectron spectroscopy and magnetic measurements using a SQUID magnetometer link this effect to the diffusion and incorporation of dopant atoms from the transparent conducting substrate. In addition, examining the optical properties of the films reveals a considerable change in the absorption coefficient and onset properties, critical aspects for hematite as a solar energy converter, as a function of the sintering temperature. A detailed investigation into hematite's crystal structure using powder X-ray diffraction with Rietveld refinement to account for these effects correlates an increase in a C(3v)-type crystal lattice distortion to the improved optical properties., DOI = 10.1021/ja101564f, ISSN = 0002-7863, Unique-ID = ISI:000278190600045, -
J. Pechousek, R. Prochazka, D. Jancik, J. Frydrych, and M. Mashlan, “Universal LabVIEW-powered Mossbauer spectrometer based on USB, PCI or
PXI devices,” in INTERNATIONAL CONFERENCE ON THE APPLICATIONS OF THE MOSSBAUER EFFECT
(ICAME 2009), 2010.
[Bibtex]@inproceedings ISI:000287181700006, Author = Pechousek, J. and Prochazka, R. and Jancik, D. and Frydrych, J. and Mashlan, M., Editor = Muller, H and Reissner, M and Steiner, W and Wiesinger, G, Title = Universal LabVIEW-powered Mossbauer spectrometer based on USB, PCI or PXI devices, Booktitle = INTERNATIONAL CONFERENCE ON THE APPLICATIONS OF THE MOSSBAUER EFFECT (ICAME 2009), Series = Journal of Physics Conference Series, Year = 2010, Volume = 217, Note = International Conference on the Applications of the Mossbauer Effect, Vienna Univ Technol, Vienna, AUSTRIA, JUL 19-24, 2009, Abstract = A new design of the universal Mossbauer spectrometer is presented. Hardware solution is based on commercial-available data acquisition devices working on the USB, PCI or PXI platform controlled by the main application running on the personal computer. Final application allows, in addition to Mossbauer spectra accumulation, the detailed analysis of the acquired detector signal in energy and time domains, and also to tune the velocity driving system separately. The experimental results show a high flexibility in various detectors and velocity transducers usage. It is easy to change the way of operation according to the different experimental requirements. This concept can be used with all common spectrometric benches with different velocity transducers, radioactive sources and gamma-ray detectors. This is a new approach in the Mossbauer spectrometer construction., DOI = 10.1088/1742-6596/217/1/012006, Article-Number = 012006, ISSN = 1742-6588, Unique-ID = ISI:000287181700006, -
J. Pechousek, R. Prochazka, J. Cuda, J. Frydrych, and D. Jancik, “Investigation of the Mossbauer Spectrum Quality as a Dependence on the
Frequency of the Velocity Signal,” in MOSSBAUER SPECTROSCOPY IN MATERIALS SCIENCE – 2010, 2010, pp. 134-142.
[Bibtex]@inproceedings ISI:000281606200019, Author = Pechousek, J. and Prochazka, R. and Cuda, J. and Frydrych, J. and Jancik, D., Editor = Tucek, J and Miglierini, M, Title = Investigation of the Mossbauer Spectrum Quality as a Dependence on the Frequency of the Velocity Signal, Booktitle = MOSSBAUER SPECTROSCOPY IN MATERIALS SCIENCE - 2010, Series = AIP Conference Proceedings, Year = 2010, Volume = 1258, Pages = 134-142, Note = International Conference on Mossbauer Spectroscopy in Materials Science, Liptovsky Jan, SLOVAKIA, JAN 31-FEB 05, 2010, Abstract = This paper is focused on a quality characterizing the Mossbauer spectra measured for various frequencies of the velocity signal. Standard electromechanical double-loudspeaker drive and digital PID velocity controller were used for calibration spectra measurement in the frequency interval from 4 up to 100 Hz. Several parameters were evaluated for recommendation of the suitable velocity signal frequency., DOI = 10.1063/1.3473890, ISSN = 0094-243X, ISBN = 978-0-7354-0806-7, Unique-ID = ISI:000281606200019, -
R. Prochazka, J. Pechousek, and J. Frydrych, “Development of the Fast Scintillation Detector with Programmable High
Voltage Adjustment Suitable for Mossbauer Spectroscopy,” in MOSSBAUER SPECTROSCOPY IN MATERIALS SCIENCE – 2010, 2010, pp. 143-149.
[Bibtex]@inproceedings ISI:000281606200020, Author = Prochazka, R. and Pechousek, J. and Frydrych, J., Editor = Tucek, J and Miglierini, M, Title = Development of the Fast Scintillation Detector with Programmable High Voltage Adjustment Suitable for Mossbauer Spectroscopy, Booktitle = MOSSBAUER SPECTROSCOPY IN MATERIALS SCIENCE - 2010, Series = AIP Conference Proceedings, Year = 2010, Volume = 1258, Pages = 143-149, Note = International Conference on Mossbauer Spectroscopy in Materials Science, Liptovsky Jan, SLOVAKIA, JAN 31-FEB 05, 2010, Abstract = This work is focused on a development of a compact fast scintillation detector suitable for Mossbauer spectroscopy (low energy X-ray/y-ray detection) where high counting rates are inevitable. Optimization of this part was necessary for a reliable function, better time resolution and to avoid a detector pulses pile-up effect. The pile-up effect decreases the measurement performance, significantly depends on the source activity and also on the pulse duration. Our new detection unit includes a fast scintillation crystal YAP:Ce, an R6095 photomultiplier tube, a high voltage power supply socket C9028-01 assembly, an AD5252 digital potentiometer with an 12C interface and an AD8000 ultra fast operation preamplifier. The main advantages of this solution lie in a short pulse duration (less than 200 ns), stable operation for high activities, programmable gain of the high voltage supply and compact design in the aluminum housing., DOI = 10.1063/1.3473891, ISSN = 0094-243X, ISBN = 978-0-7354-0806-7, Unique-ID = ISI:000281606200020,
2009
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C. Park, J. Walker, R. Tannenbaum, A. E. Stiegman, J. Frydrych, and L. Machala, “Sol-Gel-Derived Iron Oxide Thin Films on Silicon: Surface Properties and
Interfacial Chemistry,” ACS APPLIED MATERIALS & INTERFACES, vol. 1, iss. 9, pp. 1843-1846, 2009.
[Bibtex]@article ISI:000270363600001, Author = Park, Chi-dong and Walker, Jeremy and Tannenbaum, Rina and Stiegman, A. E. and Frydrych, J. and Machala, L., Title = Sol-Gel-Derived Iron Oxide Thin Films on Silicon: Surface Properties and Interfacial Chemistry, Journal = ACS APPLIED MATERIALS \& INTERFACES, Year = 2009, Volume = 1, Number = 9, Pages = 1843-1846, Month = SEP, Abstract = Uniform high-quality iron oxide thin films can be formed from the spin coating of iron oxide/hydroxide sol-gels on a silicon substrate. Thermal processing of the films at temperatures of similar to 300 degrees C results in the transformation of films into a ternary layered structure with Iron oxide, Fe(2)O(3), at the surface, characterized by Mossbauer spectroscopy. and reduced Metallic iron characterized by depth profiling of the surface by X-ray photoelectron spectroscopy as a function of Ar(+) etching. Imaging of the etched surface by scanning electron microscopy reveals two distinct regions at the interface, nanoparticles that are very iron-rich separated by an unstructured region that is somewhat less iron-rich. The results demonstrate a synthetic protocol for the spontaneous formaton of a ternary layered structure from a simple one-step preparation., DOI = 10.1021/am900362x, ISSN = 1944-8244, Unique-ID = ISI:000270363600001, -
J. Pechousek, R. Prochazka, M. Mashlan, D. Jancik, and J. Frydrych, “Digital proportional-integral-derivative velocity controller of a
Mossbauer spectrometer,” MEASUREMENT SCIENCE & TECHNOLOGY, vol. 20, iss. 1, 2009.
[Bibtex]@article ISI:000261627800038, Author = Pechousek, J. and Prochazka, R. and Mashlan, M. and Jancik, D. and Frydrych, J., Title = Digital proportional-integral-derivative velocity controller of a Mossbauer spectrometer, Journal = MEASUREMENT SCIENCE \& TECHNOLOGY, Year = 2009, Volume = 20, Number = 1, Month = JAN, Abstract = The digital proportional-integral-derivative (PID) velocity controller used in the Mossbauer spectrometer implemented in field programmable gate array (FPGA) is based on the National Instruments CompactRIO embedded system and LabVIEW graphical programming tools. The system works as a remote system accessible via the Ethernet. The digital controller operates in real-time conditions, and the maximum sampling frequency is approximately 227 kS s(-1). The system was tested with standard sample measurements of alpha-Fe and alpha-(57)Fe(2)O(3) on two different electromechanical velocity transducers. The nonlinearities of the velocity scales in the relative form are better than 0.2\%. The replacement of the standard analog PID controller by the new system brings the possibility of optimizing the control process more precisely., DOI = 10.1088/0957-0233/20/1/017001, Article-Number = 017001, ISSN = 0957-0233, Unique-ID = ISI:000261627800038,
2008
- J. Frydrych, M. Mashlan, J. Pechousek, and D. Jancik, “Conversion Electron Detectors for (57)Fe Mossbauer Measurements,” in MOSSBAUER SPECTROSCOPY IN MATERIALS SCIENCE 2008, 2008, pp. 170-184.
[Bibtex]@inproceedings ISI:000262290200021, Author = Frydrych, J. and Mashlan, M. and Pechousek, J. and Jancik, D., Editor = Mashlan, M and Zboril, R, Title = Conversion Electron Detectors for (57)Fe Mossbauer Measurements, Booktitle = MOSSBAUER SPECTROSCOPY IN MATERIALS SCIENCE 2008, Series = AIP Conference Proceedings, Year = 2008, Volume = 1070, Pages = 170-184, Note = International Conference on Mossbauer Spectroscopy in Materials Science, Hlohovec u Breclavi, CZECH REPUBLIC, JUN 16-20, 2008, Abstract = This review article is intended to help all those, who now begin to work in the field of conversion electron Mossbauer spectroscopy (CEMS) and who have to select a right type of a detector. There exist a large number of specific engineering designs in each of the detector kind, which is impossible to cover in one paper. That is why we only try to outline basic classification and general survey of properties of individual CEMS detector kinds supplemented by references to its more detailed analysis. (57)Fe is the most frequently used isotope in CEMS and thereby the paper is devoted to this case., ISSN = 0094-243X, ISBN = 978-0-7354-0601-8, Unique-ID = ISI:000262290200021,
2007
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J. Pechousek, M. Mashlan, J. Frydrych, D. Jancik, and R. Prochazka, “Improving detector signal processing with pulse height analysis in
Mossbauer spectrometers,” HYPERFINE INTERACTIONS, vol. 175, iss. 1-3, pp. 1-8, 2007.
[Bibtex]@article ISI:000256911000001, Author = Pechousek, Jiri and Mashlan, Miroslav and Frydrych, Jiri and Jancik, Dalibor and Prochazka, Roman, Title = Improving detector signal processing with pulse height analysis in Mossbauer spectrometers, Journal = HYPERFINE INTERACTIONS, Year = 2007, Volume = 175, Number = 1-3, Pages = 1-8, Month = FEB, Abstract = A plenty of different programming techniques and instrument solutions are used in the development of Mossbauer spectrometers. Each of them should provide a faster spectrum accumulation process, increased productivity of measurements, decreased nonlinearity of the velocity scale, etc. The well known virtual instrumentation programming method has been used to design a computer-based Mossbauer spectrometer. Hardware solution was based on two commercially-available PCI modules produced by National Instruments Co. Virtual Mossbauer spectrometer is implemented by the graphical programming language LabVIEW 7 Express. This design environment allows to emulate the multichannel analyzer on the digital oscilloscope platform. This is a novel method based on Waveform Peak Detection function which allows detailed analysis of the acquired signal. The optimal treatment of the detector signal from various detector types is achieved by mathematical processing only. As a result, the possibility of an increase of signal/noise ratio is presented., DOI = 10.1007/s10751-008-9580-5, ISSN = 0304-3843, Unique-ID = ISI:000256911000001,
