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237 results on '"Pawlyta, Mirosława"'

2. InGaAs metamorphic buffers grown by MBE on GaAs affect the excitonic and optical properties of single InAs quantum dots while tuning their single photon emission to the telecom range

Author

Wyborski, Paweł, Gawełczyk, Michał, Podemski, Paweł, Wroński, Piotr Andrzej, Pawlyta, Mirosława, Gorantla, Sandeep, Jabeen, Fauzia, Höfling, Sven, and Sęk, Grzegorz

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

Tuning GaAs-based quantum emitters to telecom wavelengths makes it possible to use the existing mature technology for applications in, e.g., long-haul ultra-secure communication in the fiber networks. A promising method re-developed recently is to use a metamorphic InGaAs buffer that redshifts the emission by reducing strain. However, the impact of such a buffer causes also a simultaneous modification of other quantum dot properties. Knowledge of these effects is crucial for actual implementations of QD-based non-classical light sources for quantum communication schemes. Here, we thoroughly study single GaAs-based quantum dots grown by molecular-beam epitaxy on specially designed, digital-alloy InGaAs metamorphic buffers. With a set of structures varying in the buffer indium content and providing quantum dot emission through the telecom spectral range up to 1.6 $\mu$m, we analyze the impact of the buffer and its composition on QD structural and optical properties. We identify the mechanisms of quantum dot emission shift with varying buffer composition. We also look into the charge trapping processes and compare excitonic properties for different growth conditions with single-dot emission successfully shifted to both, the second and the third telecom windows., Comment: 20 pages, 12 figures

Published
2023

4. Formation of Zn and Pb sulfides in a redox-sensitive modern system due to high atmospheric fallout

Author

Smieja-Król, Beata, Pawlyta, Mirosława, Kądziołka-Gaweł, Mariola, and Fiałkiewicz-Kozieł, Barbara

Subjects
Condensed Matter - Materials Science
Abstract

The study shows that the air-derived metal enrichment (up to 2.3 g Zn kg-1, 1.1 g Pb kg-1, and 62 mg Cd kg-1) is retained in a thin layer (~30 cm) around 10-15 cm below the peat surface. A combination of focused ion beam (FIB) technology and scanning (SEM) and transmission (TEM) electron microscopy reveals that micrometric spheroids are most characteristic for ZnS and (Zn,Cd)S, although the sulfides readily form pseudomorphs after different plant tissues resulting in much larger aggregates. The aggregates have a complex polycrystalline sphalerite structure much more advanced than typically obtained during low-temperature synthesis or observed in other modern occurrences. Platy highly-disordered radially-aggregated submicrometre crystals develop within the time constraints of several decades in the cold (~15{\deg}C) and acid (pH 3.4-4.4) peat. The less abundant Pb sulfides occur as submicron cube-like crystals between ZnS or as flat irregular or square patches on plant root macrofossils. All PbS are crystalline and defect-free. Pb ion complexation with dissolved and solid organic matter is probably responsible for the low number and equilibrium shape of PbS crystals. Iron is absent in the authigenic sulfide mineralization and occurs entirely as organically bound ferric iron (Fe3+), as revealed by Mossbauer spectroscopy. The different affinity of metals to organic matter enhances the precipitation of Zn and Cd as sulfides over Pb and Fe. Our findings demonstrate that human activities lead to the formation of near-surface stratiform metal sulfide accumulations in peat, and the polluted sites can be of use to understand and reconstruct ancient ore deposits' genesis and mechanisms of formation., Comment: with supplementary material

Published
2022
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24. Artificial Manganese Metalloenzymes with Laccase-like Activity: Design, Synthesis, and Characterization

Author

Garcia-Sanz, Carla, Andreu, Alicia, Pawlyta, Mirosława, Vukoičić, Ana, Milivojević, Ana, de las Rivas, Blanca, Bezbradica, Dejan, Palomo, Jose M., Garcia-Sanz, Carla, Andreu, Alicia, Pawlyta, Mirosława, Vukoičić, Ana, Milivojević, Ana, de las Rivas, Blanca, Bezbradica, Dejan, and Palomo, Jose M.

Abstract

Laccase is an oxidase of great industrial interest due to its ability to catalyze oxidation processes of phenols and persistent organic pollutants. However, it is susceptible to denaturation at high temperatures, sensitive to pH, and unstable in the presence of high concentrations of solvents, which is a issue for industrial use. To solve this problem, this work develops the synthesis in an aqueous medium of a new Mn metalloenzyme with laccase oxidase mimetic catalytic activity. Geobacillus thermocatenulatus lipase (GTL) was used as a scaffold enzyme, mixed with a manganese salt at 50 °C in an aqueous medium. This leads to the in situ formation of manganese(IV) oxide nanowires that interact with the enzyme, yielding a GTL-Mn bionanohybrid. On the other hand, its oxidative activity was evaluated using the ABTS assay, obtaining a catalytic efficiency 300 times higher than that of Trametes versicolor laccase. This new Mn metalloenzyme was 2 times more stable at 40 °C, 3 times more stable in the presence of 10% acetonitrile, and 10 times more stable in 20% acetonitrile than Novozym 51003 laccase. Furthermore, the site-selective immobilized GTL-Mn showed a much higher stability than the soluble form. The oxidase-like activity of this Mn metalloenzyme was successfully demonstrated against other substrates, such as l-DOPA or phloridzin, in oligomerization reactions.

Published
2024

30. Impact of MBE-grown (In,Ga)As/GaAs metamorphic buffers on excitonic and optical properties of single quantum dots with single-photon emission tuned to the telecom range

Author

Wyborski, Paweł, primary, Gawełczyk, Michał, additional, Podemski, Paweł, additional, Wroński, Piotr Andrzej, additional, Pawlyta, Mirosława, additional, Gorantla, Sandeep, additional, Jabeen, Fauzia, additional, Höfling, Sven, additional, and Sęk, Grzegorz, additional

Published
2023
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35. Synthesis of Pt nanowires with the participation of physical vapour deposition

Author

Dobrzański Leszek A., Szindler Marek, Pawlyta Mirosława, Szindler Magdalena M., Boryło Paulina, and Tomiczek Błazej

Subjects
nanotechnology, nanomaterials, nanowires, physical vapour deposition, 61.46.+w, 61.46.np, 61.46.-w, Physics, QC1-999
Abstract

The following paper presents the possibility of formation of Pt nanowires, achieved by a three-step method consisting of conformal deposition of a carbon nanotube and conformal coverage with platinum by physical vapour deposition, followed by removal of the carbonaceous template. The characterization of this new nanostructure was carried out through scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD).

Published
2016
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38. High-Surface-Area Graphene Oxide for Next-Generation Energy Storage Applications

Author

Zięba, Wojciech, primary, Jurkiewicz, Karolina, additional, Burian, Andrzej, additional, Pawlyta, Mirosława, additional, Boncel, Sławomir, additional, Szymański, Grzegorz S., additional, Kubacki, Jerzy, additional, Kowalczyk, Piotr, additional, Krukiewicz, Katarzyna, additional, Furuse, Ayumi, additional, Kaneko, Katsumi, additional, and Terzyk, Artur P., additional

Published
2022
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44. Zn, Cd and Hg doping of AgInS2 quantum dots – efficient strategy to modify nonlinear absorption.

Author

Kosman, Rafał, Wawrzyńczyk, Dominika, Nyk, Marcin, Pawlyta, Mirosława, Bezkrovnyi, Oleksii, and Cichy, Bartłomiej

Abstract

This work aims to investigate a possible strategy to enhance the nonlinear optical absorption in a well-known group of defect-rich ternary AgInS2 quantum dots. In this work, we propose that hosting of Zn2+, Cd2+ and Hg2+ ions in the AgInS2 structure can be an effective way to tune optical nonlinearities in the quantum dots of the I–II–VI system. Non-linear refraction and non-linear absorption in the AgInS2:Zn2+, AgInS2:Cd2+ and AgInS2:Hg2+ quantum dots were measured over a wide range of wavelengths (550–1800 nm) using the Z-scan technique. The results showed that the changes caused by the doping of AgInS2 quantum dots with heavier Zn homologues are of different nature. The observed differences are discussed here in terms of changes in the electronic structure of defects under the influence of Zn, Cd and Hg doping. Distinct spectral changes induced by hosting Zn2+, Cd2+ and Hg2+ ions are also well resembled in the nonlinear excitation regime. It is shown that Cd2+ doping and Hg2+ ions have much greater impact on the two-photon (σ2) and three-photn (σ3) absorption cross section enhancement than zinc doping. The results indicate that the two- and three-photon absorption cross section values can be significantly increased by the adopted doping strategy, and the AgInS2 quantum dots may be even better suited not only to the two-photon but also to the three-photon fluorescent techniques commonly used for bio-sensing applications. [ABSTRACT FROM AUTHOR]

Published
2023
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45. Metal–Support Interaction and Charge Distribution in Ceria-Supported Au Particles Exposed to CO

Author

Bezkrovnyi, Oleksii, primary, Bruix, Albert, additional, Blaumeiser, Dominik, additional, Piliai, Lesia, additional, Schötz, Simon, additional, Bauer, Tanja, additional, Khalakhan, Ivan, additional, Skála, Tomáš, additional, Matvija, Peter, additional, Kraszkiewicz, Piotr, additional, Pawlyta, Mirosława, additional, Vorokhta, Mykhailo, additional, Matolínová, Iva, additional, Libuda, Jörg, additional, Neyman, Konstantin M., additional, and Kȩpiński, Leszek, additional

Published
2022
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49. Structure and tribological properties of DLC:Si/AlCrN low friction thin film

Author

Paradecka Agnieszka, Lukaszkowicz Krzysztof, and Pawlyta Mirosława

Subjects
Engineering (General). Civil engineering (General), TA1-2040
Abstract

A wide range of diamond-like carbon coatings is caused by their structure composed of sp2 and sp3 carbon hybridisation and the possibility of both metallic and non-metallic admixtures or the creation of a hydrogenated form. One of the ways to improve the tribological properties of DLC is to dope it with silicon. Deposited on stainless steel substrate coating system composed of AlCrN film covered by DLC:Si was the subject of the studies. The AlCrN and DLC:Si layers were deposited by PVD lateral rotating ARC-cathodes and PACVD on the X6CrNiMoTi17-12-2 steel respectively. Characteristics of DLC:Si film was performed by imaging the topography using SEM and AFM. The structure was investigated using a Raman spectroscopy and HRTEM. Tribological and adhesion tests were carried out using a ball-on-disc and a scratch test respectively. Tests using the TEM confirmed an amorphous character of DLC:Si layer. A phase composition analysis of the DLC:Si layer with the Raman spectroscopy method showed the presence of bonds distinctive for diamond (sp3) and graphite (sp2), typically observed in DLC coatings. Under the technically dry friction conditions, the friction coefficient for the associations tested is within the range 0.14 for the investigated coating.

Published
2019
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